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HSI1000 Notes
How Science Works, Why Science Works (National University of Singapore)
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Lecture 1 - The Founding of Modern Science
Chapter 1 - Science
Describe what is science and explain the scientific method “in a nut shell” illustrating
your explanation with a straightforward example
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Science is that activity which aims to further our understanding of why things happen
as they do in the natural world. It accomplishes this goal by applications of scientific
method—the process of observing nature, isolating a facet that is not well understood
and then proposing and testing possible explanations.
Science can be applied to anything that has an observable and tangible effect in the world.
Scientific Method:
1. Observe
2. Explain
3. Test
Galileo
- Aristotelian world view simply reinforces the idea that all objects when given a push
will come to rest because coming to rest is the nature of solid objects. This is
because solid objects are of the Earth, and the Earth doesn’t move, in the Aristotelian
world view.
- Galileo observed this exact same thing he came to the exact opposite conclusion
- He was not contaminated by expectation or belief in the Aristotelian world view
- He realized that an object’s nature being supposedly stationary was pure conjecture
(an opinion or conclusion formed on the basis of incomplete information), a belief,
and not a fact.
- It was the nature of the contact between the object and the surface that caused the
object to slow down, not the nature of the object itself.
- Galileo was only able to do this because he: (considerations when making scientific
observations)
- Had a very clear sense of what the relevant and irrelevant phenomena were.
- He didn’t overlook anything when carefully observing how objects moved on a
surface.
- He knew all too well what was based on fact and conjecture in the Aristotelian
view of how objects moved, and he certainly made sure his observations
were
- Not contaminated by expectation or belief.
- What did Galileo come to realize was responsible for an object's slowing down then
coming to rest?
- How significant the contact was between the object and the surface it was on.
- What best describes the "extraneous effect" that was obscuring clear-sighted
observations of objects moving across a surface after being given an initial push?
- The slowing down of the object because of significant contact with the
surface.
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Chapter 2 - Observations
● What three roles does observation play in scientific inquiry?
1. Observation can enable us to identify and focus in on the relevant facts about the
phenomena under investigation. (Passive and empirical observations to develop
questions about a phenomenon or process.)
a. Passive - gaining knowledge from noticing how something works, without
directly affecting the process of outcome
b. Empirical - based on observation or experience
2. What we observe can provide clues as to what might explain the phenomena.
3. Observational data can provide the evidence by which we can determine whether
various explanations succeed or fail.
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Why is it crucial to define terms prior to making a set of observations?
Data relevant to these questions cannot be collected until key terms are clarified.
Without a clear sense of how these key terms are being used, subsequent research
cannot get off the ground.
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How does a fact differ from an assumption? Can assumptions be factual?
Fact: something that I know about the phenomena under investigation
Assumptions: what am I assuming based on what I have been told or have heard,
read, etc?
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What role can comparative information play in the process of making a set of
observations?
Part of the point of making a set of observations is to determine what, if anything, is
unusual about the data collected.
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What is confirmation bias?
The tendency to selectively focus on evidence that supports our beliefs while
rejecting disconfirming evidence is called confirmation bias.
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What effect can expectation and belief have on observation?
If we suspect, in advance of careful observation, that a claim is true, we may
inadvertently overlook data contrary to our belief.
● What are the defining features of an extraordinary claim?
1. All are highly controversial, in the sense that though there is some evidence for the
truth of each, the evidence is sketchy at best.
2. All appear to be at odds with some aspect of our current understanding of the natural
world even though the claims generally do not emerge from mainstream science.
3. Advocates of such claims are often unaware of the extent to which their beliefs are in
disagreement with established scientific theory.
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What is an anomaly? Why is the discovery of anomalous phenomena important
for science?
An anomaly is something, some state of affairs, that does not square with current,
received ways of understanding nature.
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Such phenomena can provide a way of testing the limits of our current understanding
of how nature works and can suggest new and fruitful areas for scientific
investigation.
Anomalous phenomena are important in science because:
- their resolution can lead to entire new fields of scientific study.
- their resolution can lead to new insights and understanding of nature.
- their resolution can lead to new instrumentation or experimental methods to
study nature, allowing further new discoveries to take place.
- their resolution provides an excellent test of what is generally accepted to be
true.
Anomalies are puzzling and unfamiliar and they are potentially revolutionary as well.
Because so much is at stake the investigation of anomalies must be undertaken with
two goals in mind.
- The first, of course, is to uncover the facts, to get a sense of what is going on.
- The second is to determine whether the phenomena can be “explained away.”
It is always a good idea to look for information that has been overlooked by those
making the claims.
Why do extraordinary claims require extraordinary evidence?
Because so much is at stake, we are entirely justified in demanding extraordinarily
decisive evidence for our psychic’s claim to influence objects telekinetically.
If an extraordinary claim were to be true, then some aspect of well-established
science would require revision.
Such claims typically fly directly in the face of our current understanding of the world,
an understanding obtained from an extraordinarily large body of evidence.
The burden of proof, in other words, lies with the person who claims to have
observed something anomalous.
The more extraordinary the anomalous claim—the more extensive the evidence it is
false—the more rigorous must be the evidence required before accepting the claim
● 5 concerns that should be addressed when making careful observations:
1. Do we have a clear sense of what the relevant phenomena are?
2. Have we found a way to insure we have not overlooked anything in the process of
making our observations?
3. What do we know for sure? What is based on fact and what on conjecture or
assumption?
4. Have we considered any necessary comparative information?
5. Have our observations been contaminated by expectation or belief?
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In the context of the scientific revolution, discuss the difference between an
evidence-based understanding of the natural world versus one based on
authority.
They were an authority – meaning that their word could not be argued with, and it
was a crime to do so – a crime called heresy
Evidenced-based understanding: A scientist should not simply accept an explanation
as true, but should doubt it and try to disprove it through observation and
experimentation, i.e., empiricism. Only then, when all possible testing has been
conducted, could one hope that the explanation may indeed be true. Without this
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skepticism then there is no basis, or evidence, that the explanation is correct, we are
forced to conclude that there’s no way of knowing if it’s true or not.
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Discuss the steam engine’s contribution to the industrial revolution and its
impact on population growth in industrialized nations.
What actually is the industrial revolution?
- Well, it commonly refers to a period of great societal change that took place,
first in Britain, Western Europe, followed by the US and Canada and later
Japan and other countries as they too industrialized.
- It occurred around the late 1700s up until about the early 1800s for Europe
and Northern America
Greatest impact on society during the industrial revolution
As an example of just how much more effective the machines were- mechanized
cotton spinning, powered by the steam engine increased the output of a worker by a
massive factor of 500
City populations increased rapidly. Average income exhibited unprecedented,
sustained growth. The standard of living for the general population increased
consistently for the first time in history, and overall there was a massive population
explosion
Steam engine power machines to do the work much more effectively and efficiently.
Textiles were the primary products impacted by the revolution in terms of
employment, value-added and capital investment
Mechanized cotton spinning
Iron production was also greatly enhanced using the steam engine to power blast air
into the furnaces
The demand for coal to power steam engines increased dramatically. Now to get
coal, you have to mine it, and Britain had lots of it.
Steam engine powered trains and ships were invented, vastly increasing the
efficiency of moving materials around, including food which now was in great demand
in the rapidly growing cities
The improvements to agriculture, just prior to the industrial revolution, coupled with
new machinery now available to assist in farming and effective means of getting it to
where it was needed (steam engine) significantly reduced famine across Western
Europe. (not throughout the world)
Population predictions
- There was a substantial overall drop in the mortality rate of the population. People,
on average, survived longer – long enough to have children of their own. So, while
the birth rate was high, roughly 6 babies per woman on average across the world, the
mortality rate in the industrialized countries decreased markedly.
- Mortality is highly predictable and that predicting how many children surviving to
become adults is also highly predictable.
- How many children there will be born is the hardest part.
Why the world population doubled over the course of industrial revolution?
1. The improvements in agriculture allowing more food to be produced.
2. There were improvements in distributing that food, reducing the likelihood of food
shortages.
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3. Improvements in sanitation with sewage systems put in place in cities.
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Those nations that underwent a period of social and economic change that
transformed the society from essentially agrarian (rural) into one heavily reliant on
manufacturing underwent a massive population surge resulting in the world’s total
population increasing markedly.
Those nations embracing new technology and mechanization replacing what use to
be done by hand far less efficiently were able to reduce their mortality rates
considerably during the industrial revolution.
there was another even more incredible population surge just around the corner, in
the 20th century. And it’s this surge in world population that truly takes us into the
climate crisis and loss of biodiversity at rates usually only associated with extinction
level events.
Surge in world population that truly takes us into the climate crisis and loss of biodiversity at
rates usually only associated with extinction level events.
Concept Quiz
Science is best characterized by its basic aim:
- Science is that activity which aims to further our understanding of why things happen
as they do in the natural world by the application of the scientific method.
The well-established theories found in our scientific textbooks are the product of the
following process:
- Rigorous testing and experimentation that eliminates erroneous explanations
Why did Prof Bettens feel that the results of the test did not confirm the proposed
explanation but only supported it?
- We would have to do much more testing in order to check that this explanation is
indeed the correct one.
How long did the concept of “cadaver matter” run against scientific consensus before the
establishment of Germ Theory?
- 30 years
Who use the scientific method well before the scientific scientific revolution?
- Hazan Ibn-Haytham made significant contributions to the principles of optics and
visual perceptions.
Nicolaus Copernicus’ proposal opposed which accepted idea of that time?
- The Sun and other planets rotated about the Earth.
But with a Scientific community, individual work can be check, and cross-checked, closely
examined by all – accelerating the pace of knowledge acquisition many fold.
Good observation necessarily need to be verifiable by other people.
Which country’s reliance on coal to fuel their steam engines kickstarted our reliance on fossil
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fuels?
- England
What was most emphasized in the video that when coupled with pollution from the incessant
coal burning during the Industrial Revolution, worsened the conditions of the newly highly
populated cities?
- Poor hygiene conditions
People
- American Physicist, historian, and philosopher of science, Thomas Kuhn (Figure 10)
who wrote about scientific revolutions, in general, in his book “The Structure of
Scientific Revolutions”
- Hazan Ibn-Haytham made significant contributions to the principles of optics and
visual perceptions. (use the scientific method well before the scientific scientific
revolution)
Scientific Revolution
1. Nicolaus Copernicus who, in 1543, published an astronomy book, known in short
form as De Rev (Figure 13), on how the planets orbited the Sun and NOT the Earth,
and that the Earth itself rotated. This proposal was in direct opposition to the
accepted idea that the Earth was the center of the universe, and that everything
rotated about the Earth
- For 1500 years, an extremely complicated system was devised for the motion of the
planets where the Sun and the moon orbited around the Earth. This has been
attributed to Ptolemy, a second century astronomer of Alexandria under the rule of
the Roman Empire.
- Copernicus’s view of how the planets moved replaced the complex Ptolemy
system. It’s important to realize that Copernicus’s newer and simpler system
wasn’t any better at predicting where the planets would be than the Ptolemy
system, mostly because Copernicus believed, as Ptolemy did, that the
planets and moon must move in perfect circular orbits with uniform speed. But
nonetheless, Copernicus’ proposal was definitely a step in the right direction.
- Copernicus just assumed that heavenly bodies must move in perfect circular
orbits with uniform speed just like Ptolemy (Do we know for sure what is
based on fact and what on conjecture or assumption?)
- Copernicus didn’t make many observations. Most of his data was recorded by
others and he took them all at face value assuming there were all good and
accurate. (Have our observations been contaminated by expectation of
beliefs?)
2. Galileo Galilei, who in the late 1500s, early 1600s, studied the motion of objects with
experiments to test current explanations of how things moved. He also performed
astronomical observations to test Copernicus’ suggestion of a Sun-centered universe
instead of an Earth Centered one and to test the Aristotelian view of the heavenly
bodies.
- It was Galileo’s work in astronomy that really got him into trouble. You see, Galileo
built powerful telescopes possessing a magnification of 30 times which was much
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more powerful than the telescope of that time which only had 3x magnification.
With this telescope he tested the Aristotelian view of the heavenly bodies and a
whole bunch of new phenomena could be plainly seen by any who cared to look.
So, with Galileo’s much more powerful telescope than anything that was available at
the time he saw a whole bunch of anomalous phenomena:
- The sun had sunspots and indicated it was rotating.
- The moon was bumpy and cratered looking like there were mountains on it
- He saw 4 moons orbiting around Jupiter
- He also recorded all the phases of Venus, which was a prediction and a test
of a Sun-centered universe. Seeing all the phases of Venus proved it orbited
the sun, because in an earth-centered universe you wouldn’t be able to see
all the phases of Venus.
All these observations lead Galileo to the realize that the Aristotelian world view must
be wrong, and that the Sun, not the Earth, was the center of the universe.
3. Johannes Kepler, who was also working at around the same time as Galileo,
proposed an improved model for how the planets moved over Copernicus’ model.
Kepler, who had access to some of the most accurate measurements of planet
positions during the year, simply could not get the positions of the planets to match
with a model like Copernicus’s, where the orbits were perfectly circular executing
uniform circular motion.
- came up with the idea of the planets orbiting about the Sun in ellipses, rather
than circles. Along with his other laws of planetary motion, he produced the
most accurate predictions, up until that time anyway, of where all the planets
would be at any time of year
4. Francis Bacon articulate the scientific method we have been disucssing in the 1620.
Sometimes called the father of empiricism (evidence-based), Bacon convinced the
fledgling scientific community that the only way to get to the truth of some
explanation was by testing it through observation or experimentation
5. Isaac Newton who integrated the earlier work of Galileo on how objects move and
Kepler’s work on how heavenly bodies move, along with the work of others and his
own experimentations.
- Newton presented his three laws of motion, which were figured out by
observations and experimentation on how objects moved on Earth.
- He also presented the law of universal gravitation which described how all
objects with mass attracted each other.
Lecture 2 - The Baloney Toolkit Applied in a Simple Investigation
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This toolkit was first created and discussed by the popular science author and
scientist Carl Sagan in the last chapter of his book: “The Demon-Haunted World:
Science as a Candle in the Dark”
1. Explain the three things you should do before applying the baloney detection
toolkit (BDTK).
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1. Possess a Skeptical Mindset
- Any explanation in science is to be given any credibility, it needs to be tested to see if
it is false - otherwise it is mere speculation. If we have an explanation that is
falsifiable then we have a scientific explanation.
- This type of thinking is along the lines of Karl Popper’s philosophy of science, whose
ideas we implicitly follow in much of this module. Remember we mentioned Thomas
Kuhn in lecture 1, and he disagrees with Popper’s philosophy in certain aspects
2. Be aware of your own biases
a. Confirmation Bias - This type of bias refers to the tendency to seek out
information that supports something you already believe, and is a particularly
pernicious (harmful) subset of cognitive bias—you remember the hits and
forget the misses, which is a flaw in human reasoning. People will cue onto
things that matter to them, and dismiss the things that don’t, often leading to
the “ostrich effect,” where a subject (metaphorically) buries their head in the
sand to avoid information that may disprove their original point.
i.
A cognitive bias is a systematic pattern of deviation from norm or
rationality in judgment. Individuals create their own "subjective reality"
from their perception of the input.
b. Availability Bias - Also known as the availability heuristic, this bias refers to
the tendency to use the information we can quickly recall when evaluating a
topic or idea—even if this information is not the best representation of the
topic or idea. Using this mental shortcut, we deem the information we can
most easily recall as valid, and ignore alternative solutions or opinions.
- A good approach to overcome availability bias is make decisions after
carefully deliberating on the matter, checking and double-checking the
sources rigorously, and taking time to examine the evidence.
- Another approach to counter availability bias is to make important decisions
with a team.
- To question the rationale of such decisions, ensuring that all the known
evidence (not just the available evidence) have been considered before the
decision is made.
c. Illusory Truth Bias (a bit like brainwash) - The illusory truth bias (also known
as illusion of truth effect, validity effect, truth effect, or the reiteration effect) is
the tendency to believe false information to be correct after repeated
exposure. When truth is assessed, people rely on whether the information is
in line with their understanding or if it feels familiar. The first condition is
logical, as people compare new information with what they already know to
be true. Repetition makes statements easier to process relative to new,
unrepeated statements, leading people to believe that the repeated
conclusion is more truthful.
3. Guard your buttons
- What is meant by buttons here is: something that sets you off; something that
immediately makes you feel, and triggers strong emotions in you. You want to try and
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make sure your own emotions don’t get the better of you and override your own
critical thinking faculties
You should be aware of your feelings, so they don’t cloud your judgment.
2. List the tools in the BDTK and explain how they assist in fact-checking.
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The tools from the BDTK were originally developed by Carl Sagan, and have been
updated and modified by various people like Michael Shermer over the years
What the tools do?
Tools used to detect nonsense by helping answer 3 questions:
1. Who is behind the information and why?
2. What is the evidence for the claims?
3. What do other sources say about the source and it's claims?
6 tools in BDTK
1. How reliable is the source of the claim? WHO
a. Use LATERAL reading to check on a source (see what other scientists have
to say about the work)
b. Check the author’s backgrounds, coupled with lateral reading from reliable
sources
c. Check “about page”
d. Perhaps the source is from primary scientific literature (firsthand publication in
scientific journals), but even this doesn’t guarantee reliability (some might
have questionable peer review process)
2. What is the source's perspective? WHY
a. What is their point of view?
b. Why was this information shared with you?
c. What is the purpose of the information you are looking at?
d. Funding of the source - where does the money come from that enables the
source to provide you with the information? What you are seeing could be an
advertisement to try and sell you something
e. Perspectives and biases in literature can colour something, making it seem
more or less than what it is.
f. Where does the source’s funding come from, and what is their stand?
g. Ensure no conflict of interest
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3. Is the claimant providing positive evidence? WHAT
Scientific evidence does NOT include:
a. Testimonials, eyewitness account, sworn statements, expert opinions or
signed affidavits
Scientific evidence include:
a. A physical object that can be probed and examined in every detail.
b. Repeated measurements made of a mysterious phenomenon, that can
sometimes, but not always, be reproduced under what appears to be the
same conditions by other scientists.
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Evidence must support claims - use lateral reading to establish the credibility of the
evidence (see what other reliable sources say about this evidence)
Evidence must be relevant
If evidence is an image, can check a picture with a reverse image search - Images
can be altered, taken out of context, not the right date, etc.
Videos can be taken out of context by saying they are about something else, or not
show an entire sequence, or can be edited.
Is the evidence POSITIVE? i.e. directly in support of the claim
Presence of evidence is not enough; evidence must be checked to be positive
Evidence must be reliable
Cannot be misrepresented, falsified, fabricated
use lateral reading to establish the credibility of the evidence
E.g. They have just provided evidence that there is something as yet unidentified in
the sky, assuming the photo isn’t a fake or the subject of the photo isn’t an artefact of
the image which occurred during photo taking. But again, even if you can prove the
picture isn’t a fake or artefact, it still isn’t positive evidence of a UFO. You only
have evidence that the picture isn’t a fake, the subject isn’t an image artefact, or a
weather balloon. That’s all. There can still be many possible explanations for the
phenomenon as well as ones we haven’t thought of. Claims need positive evidence
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to support them, not negative evidence against alternative explanations.
Weather - short-term atmospheric conditions
Climate - how the atmosphere behaves over relatively long periods of time
Steps for reverse image search
1. Copy the URL, or link, to the suspect picture. Typically right-clicking brings up a
context menu with one of these as an option.
2. Open a new browser window and go to https://images.google.com/
3. Click on the camera icon in the search bar ( ), which brings up a “Search by image”
dialog box.
4. Select the “Paste image URL” tab, then paste the URL you copied into the search
bar.
4. Where does the majority of evidence point?
- Well established scientific facts require a significant amount of scientific
evidence
- So generally, it’s the explanation where the majority of evidence points, is the
one that is most often correct.
- Anomalies can exist in science; they will have to be put to the test and proven
to be true.
- A minority stand could end up being false or a fraud.
5. Have the claims been verified by somebody else?
- Principle of Reproducibility/replicability is absolutely fundamental to science
- Lateral reading and use of face-checking sites would be useful for this
section.
- Fact-checking sites (www.snope.com)
- Irreproducible findings are not considered findings at all in science
- Pons and Fleischmann - In 1989 they claimed that they had discovered
something called cold fusion. The discovery that Pons and Fleischmann had
not actually detected nuclear reaction by-products.
6. Does the claimant use flawed reasoning?
- Does what they say actually make sense? Is there a flaw in the logic?
- Often when people use numbers to try and present their case, they mask the
truth by not properly accounting for an appropriate rate, which actually
invalidates their argument. As this BDTK tool says, you need to think about if
what the claimant is saying actually makes sense
- Is what being said makes sense, or are you just looking at massive numbers
presented out of context?
Cherry picking - selectively choosing evidence for something and completely ignoring
evidence against it (Where does the majority of evidence point - when you cherry pick you
ignore the majority of the evidence)
Concept quiz
Which one of the people below ideas, that we discussed during the Scientific Revolution, are
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most relevant to the Baloney Detection Toolkit
- Francis Bacon (Bacon convinced the fledgling scientific community that the only way
to get to the truth of some explanation was by testing it through observation or
experimentation)
How is examining the human world population relevant to global warming?
- Large numbers of people in industrialized nations can pump huge amounts of CO2
into the atmosphere - enough to effect the planet's climate.
If there is no evidence for a claim or explanation, does this prove the claim or explanation
wrong?
- No
Which of the tools (1 to 6) most closely aligns with the concern "Have our observations been
contaminated by expectation of beliefs?" we mentioned when making careful scientific
observations?
- What is the source's perspective?
You are checking a research journal article and you notice that conclusions of the paper
appear to support one of the organizations paying for the research. What should you do?
- Consider the quality of the journal, the expertise and affiliations of authors, and check
for a statement of no conflict in the paper before deciding what to do.
Select from the list two on-line or electronic resources we mentioned that could be used as a
reliable source of information?
- Wikipedia, OurWorldInData
We found that the human world population approximately doubled every BLANK years
during the industrial revolution?
- 138
When we used the tool, "Where does the majority of evidence point?" we discovered the
Prof Rosling was BLANK with his historical population estimates.
- a little high
Population prediction
- How many old people in the future depends on how many adults now and
- Mortality depends on age, so it is predictable
- How many adults depends on how many children, so it is predictable
- Hardest part is how many children in the future
Huge population surge after WW2
Lecture 3 - Scientific Explanations and Models
Define a scientific explanation
- It’s an account of how or why something is the case, but what makes the explanation
scientific is that it MUST be testable, or falsifiable.
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If the tests failed, then the explanation needed to be revised, or an entirely new one
provided.
A scientific explanation for something must be subject to falsification. If there’s no
way of demonstrating that the explanation is false through experimentation, or “reality
checks”, then the explanation is not scientific
What does it mean when we say a scientific explanation "must be testable"?
- There has to be the possibility of the explanation being falsified
Two basic ways in which a theory differs from a hypothesis
- Scientific explanations are frequently associated with two terms - “theory” and
“hypothesis”.
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Hypothesis: What characterizes a hypothesis is that it is tentative or unproven, that
is, it hasn’t yet been subjected to any testing or falsification. They are
speculative/hunch.
Usually the first step to discovering something new about nature
Theories: A scientific theory is characterized by the breadth and depth of its
explanatory power. Explains a wide range of phenomena.
A theory is a conceptual framework for providing explanations
Contain well tested rules and principles
E.g. Scientific theory: is functioning knowledge, not declarative knowledge
- Newton’s three laws of motion and the law of gravitation. These laws
constitute a scientific theory. They serve as a “conceptual framework” for
providing explanations for how and why a vast number of things move about
all around us.
- Germ theory explains a vast array of diseases exhibited in not just people, but
all kinds of organisms. Again, it represents a conceptual framework for
explanations of a vast array of diseases and provides insight into their
treatment
- Big Bang Theory, Quantum Mechanics, Kinetic Theory of Gases, Vanishingdimensions theory, Germ Theory, Theory of Evolution
- A set of related mathematical equations that when applied correctly reproduce
and predict what at first sight appears to be quite different phenomena.
- A set of self-consistent and unifying concepts that when applied explains and
predicts many apparently disparate observations.
Obsolete theory: Theories that were thought to be correct at the time, but eventually
came undone because of new evidence that proved them wrong
E.g. Aristotelian world view
demonic theory - Devils and demons were thought to be the cause of disease
Miasmatic theory – a theory that you could catch a disease from “bad air” or even
“night air”, i.e., disease was caused by a gas
even superseded or obsolete theories are still called theories
Novel theory: These are theories that can not only explain phenomena that are
already explained by well-established theories, but also explain, or at least hope to,
anomalies that the current theory has a hard time supporting. These theories are
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currently under investigation and being subjected to testing.
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well-established theories also have to undergo revision when new evidence is
uncovered because science is self-correcting
Difference:
1. Scientific theories are more general structures capable of explaining a much wider
variety of phenomena than a hypothesis. (proven) Hypothesis haven’t been tested.
(unproven)
2. A scientific theory will often contain experimentally well-tested, and therefore, well
confirmed rules and principles that reveal underlying explanatory similarities between
what might seem to be quite diverse phenomena.
Explain the difference between two events being correlated and being related as
cause and effect.
Causation (cause and effect/casual link):
- Providing a causal explanation may allow us to understand why such phenomenon
exist, but causal explanations may not be straightforward or simple. Here’s six
reasons why:
1. A combination of causes leading to an effect
2. Cause and effect can refer to groups
- cause and effect can be about groups rather than individual facts or
events. For example, smoking causes lung cancer means that lung
cancer occurs more frequently among those who smoke.
3. More than one cause can result in a specific effect
- Lung cancer can also be caused by elevated levels of radon – a
natural radioactive gas, asbestos exposure and elevated levels of
other chemicals like arsenic, beryllium, cadmium, coal and coke
fumes, silica and nickel.
- It can also be caused genetically, especially if it is present in the family
history.
4. An effect might not result from a given cause in every case
- For example, although smoking is the leading cause of lung cancer,
not all smokers contract lung cancer
5. Causal explanations can be negative
- For example, fluoridation of water helps prevent tooth decay, or
wearing a mask helps prevent COVID transmission
6. Causal explanations can involve a series of linked causes and effects
- Causal explanations can involve a series of linked events, like A
causing B which in turn causes C. Terms like proximate and remote
are sometimes used to describe the relationship between these
causes.
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A is a proximate cause of B. Likewise, B is a proximate cause of C. A
can be termed as a remote cause of C
What is the difference between a proximate and a remote cause?
- A causes B which in turn causes C, A is often referred to as a proximate
cause of B and a remote cause of C.
Correlation:
- Correlation is the degree to which two properties, traits or characteristics move in
coordination, or in sync, with one another.
Note:
- When we identify a cause for an effect, we expect there to be some kind of
correlation – positive or negative.
Just because two things are correlated doesn’t mean there is a causal
relationship/causal link. (correlation is not cause and effect)
- No correlation literally means no relationship, whereas negative correlation means
there is a relationship and that is where one property goes up,the other goes down
- The bottom line is, for causal relationships, like the fertility rate linked to child
mortality rate, you expect there to be a correlation.
- BUT, finding a correlation between two properties certainly doesn’t mean they are
causally linked in some way
Discuss the basic features of the following types of scientific explanations:
(a) causal mechanism
- A causal mechanism is a linked chain of causes, taking us from the remote cause,
through a series of proximate causes, eventually leading to the effect we’re
explaining
- Example: “Debris from the storm severed power lines, thus causing last night’s power
outage.”
(b) underlying processes
- Redescribe what is observed in terms of more fundamental processes (basic level)
- Not something cause something
(c) laws
- Generalized descriptions of regularities that have been found to occur in nature
- What happens if heat is applied to a closed container of a gas? Pressure increases.
Why? An important law governing the behavior of gases, discovered by Joseph GayLussac, provides the answer.
- Example: “The fuel efficiency of a vehicle is determined in part by size and weight.
This is because acceleration is directly proportional to force but inversely proportional
to mass. Thus, the larger the object you want to move, the greater the force you need
to apply, and so the more energy you need to expend.”
- Universal laws
- Boyle’s law can be used to explain the behavior of gases
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(d) function.
- Explanation based on the purpose that it serves
- Example: “The chest pain and breathing difficulty symptomatic of pneumonia result
from an infection of the lung tissue. The tiny air sacs of which the lungs are
composed—called alveoli—fill with inflammatory fluid caused by the infection. As a
result, the flow of oxygen through the alveolar walls is greatly impaired.”
Notes:
- There is an interdependence between the different ways of explaining phenomena
(e.g. laws + process to explain Boyle’s law is a call to the underlying process of this
behavior of molecules and atoms.)
- All the explanations are testable
(e) causes
- To explain one thing or event by reference to another that precedes it.
- Examples: “Debris from last night’s windstorm caused the power outage.” “Excessive
alcohol consumption can damage the liver.”
Explain Occam’s Razor, illustrating its use with an example.
- Given competing explanations, any of which would, if true, explain a given puzzle, we
should initially opt for the explanation which itself contains the least number of
puzzling notions
- Choose that explanation which is least complex and/or most plausible
- Does the claimant use flawed reasoning?
- E.g. Copernicus' explanation of how heavenly bodies move vs Ptolemy’s
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Occam’s Razor is named after William of Ockham (Figure 17), an English monk,
philosopher, and theologian believed to be born on Ockham in 1285. He has been
credited with the Occam’s Razor, a methodological principle, that we still apply today.
It can be used to help figure out which explanation is most likely to be correct.
Discuss what is a scientific model, the different types and their purpose, and explain
the difference between a model and a theory illustrating your explanation with an
example.
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A scientific model is a cut-down and simplified representation of real-world objects,
systems or events. They are idealizations of reality, with the extraneous and
hopefully irrelevant parts of reality ignored, or treated very crudely or simply.
Models aren’t just about their ability to explain phenomena. They can also be used to
test those explanations, make predictions and projections, and enhance our
understanding of nature and even aid in the research of figuring out what is going on.
3 categories of models:
1. Physical models
- These are actual physical objects representing some aspect of nature. For
example, a globe – a model of planet Earth
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But physical models, like all models, can also be used to help analyze and
study the real system they are meant to represent. There are many such
examples, like architectural models of buildings can help with visualization of
internal relationships within the structure or external relationships of the
structure to the environment.
To assist in better understanding reality, the physical model can be
augmented with instruments to make measurements of what’s happening in
and around the model. Such measurements can assist in optimization and the
design of equipment or processes. For example, the instruments may
measure the external flow of air or water around model buildings, vehicles,
people, or hydraulic structures.
Physical models can simulate complex air and water flow to a degree of
accuracy that is not possible with other types of models.
2. Mathematical/Computer models
- It’s when math can be used to describe nature in some way
- When all these equations and data are taken together, they then constitute a
mathematical model. To solve such a complicated model the equations will
often need to be programmed up on a computer for them to “number crunch”
the data with the equations and produce meaningful output.
3. Conceptual models
- Conceptual models are cut-down versions of reality with only the parts of
interest included. A map is one example. It’s a conceptual representation of
real-world physical locations and relevant objects.
- Diagrams and figures representing ideas and concepts in science can be
thought of as conceptual models
- Conceptual models of reality might appear quite similar to real world objects,
but they could also be diagrams illustrating processes, even one as abstract
as a circuit diagram. All conceptual models depict ideas and concepts within
science and can be used to explain phenomena and make predictions in the
real world, just as physical and mathematical/computer models can.
Prediction VS Projection:
- Prediction:
- something expected to happen
- Projection:
- a "what if" prediction
- something that is predicted to happen given some condition
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Of course, we should never lose sight of the fact that models, being cut-down and
simplified representations of reality, can actually leave too much of the real-world out
and end up producing the wrong results. However, because science is selfcorrecting, once such an error is discovered, the ignored effect can then be included
in the model to make an improved version. (When new information suggests that old
beliefs are false, the old beliefs are replaced by new beliefs.)
Model VS theory:
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Models can be created from the concepts and principles provided in a theory or a
hypothesis. As such, these models are concrete applications of the principles or
concepts outlined by the theory or hypothesis. Because of this, the results of these
models can actually be used to test a hypothesis.
Models are subordinate to the higher-level theory which just expresses the concepts
and principles.
For example, Newton’s statement of the three laws of motion and the law of
gravitation can be used to construct a computer model of our entire solar system, i.e.,
the Sun, planets and all their moons, to predict where the Earth and all of these
heavenly bodies will be moving into the future.
Concept quiz
When a scientific law is explained by re-describing what is observed by discussing how
molecules and atoms behave at the microscopic level, which explanatory strategy is being
used?
- Underlying process
It has been found that there is a tendency for people to simply accept sales pitches without
any evidence when a magic phase like "according to scientists" is inserted in the pitch. This
is explained by something called "anonymous authority". Which of the explanatory strategies
below most fits this explanation of people's behavior?
- Law
A reasonably accurate mathematical/computer model was used in Jan 2021 to figure out
what would be the sales price of a 1100 sqft flat at Lakeside if the Singapore Property Index
(SPI) were to become 250.0 at some point in the future (SPI in Jan 2021 is 197.3). What
term best describes the result of the model?
- Projection
Latitude is the measurement of distance north or south of the Equator.
Longitude is from east to west
Lecture 4 - Experimentation and Uncertainty
1. Describe the basic process of experimentally testing a scientific explanation
and explain the importance of eliminating false confirmation and rejection from
an experimental test.
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C: But what if careful observations can’t confirm or reject the explanation?
H: We will need to figure out something that SHOULD happen if the explanation was
actually correct. This can sometimes be quite hard and may take a lot of creativity
and imagination.
I: The next challenge after having figured out something that should happen if the
explanation were true is to devise a set of circumstances in which the predicted
outcome should occur. That is, figure out an experiment to perform to check if the
thing you predicted to happen happens. This part of science, experimental design,
can also be quite difficult.
Remember, all scientific explanations MUST be testable, or falsifiable. If the
explanation can’t be falsified, then it’s not a scientific explanation, and a new one
needs to be considered.
We can see from this flow chart how science self-corrects. You keep running through
the flow chart until something works and only then you will be on your way to learning
something new about nature
Importance of eliminating false confirmation and rejection from an experimental test
2 issues to be addressed when designing an experiment
False confirmation
- Suppose the experiment you designed to test the theory is flawed in some way. After
performing the experiment, you believe the results of it support the scientific
explanation, when, in fact, it doesn’t. This is false confirmation.
- This can happen if the result of the experiment can readily be explained by
something else. For the experiment to support the explanation, we’ll need to prove
that the alternative explanation for the result of the experiment can’t be the case.
- E.g. It was the claim that “cold fusion” was real and could essentially be produced by
a chemical reaction on a bench. Experiment was flawed, which lead to false
confirmation that cold fusion was real.
- E.g. Polywater was a hypothesized polymerized form of water. Only ever tiny
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amounts of polywater could be made, but it was reported to possess a density similar
to syrup, a much lower freezing point of -40 0C, and a boiling point of 150 degrees. It
was first reported in 1961 by Soviet scientists, but gained a lot of attention in the late
1960s. By 1969, the American public and military were very concerned that the
Soviets had a new technology that could be used against them. As this was
happening at the height of the cold war, the fear and paranoia surrounding polywater
intensified. It was hypothesized that if polywater came into contact with regular water,
it could turn all the regular water into it, utterly devastating the country.
We also see the critical importance of a scientific community here. Only when
scientists from around the world started seriously working on the problem was the
issue finally sorted out – and it took several years to do so.
False rejection
- falsely rejected your hypothesis
- false confirmation and rejection of scientific explanations due to improperly designed
experiments is a real concern. We need to carefully think through the experiments
when testing scientific hypotheses and theories.
- E.g. Recall that the first HDMI cable wasn’t functioning correctly. If I had believed it
was working correctly then I would have concluded that either the graphics card or
mother board was at fault. I would have falsely rejected the hypothesis that the
monitor display on my laptop was at fault.
- And if you don’t do it, you can rest assured that when you communicate your results
to the scientific community, someone else will.
Concept quiz
When simple straight-forward observations can't directly test a scientific explanation, how do
scientists go about testing the explanation then?
- Figure out something that should happen if the explanation were correct
In the video, polywater was an example of...
- False confirmation
What does it mean when we say a scientific explanation "must be testable"?
- There has to be the possibility of the explanation being falsified
2. Discuss how contemporary scientific research is conducted and its
relationship to testing explanations.
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1. Observation/question (observation)
- It starts with observation/question, the same as our nutshell description of the
scientific method.
- We observe something puzzling, and we want to find out how or why that something
happens or occurs.
- The question could be almost anything really, but it involves finding out something in
nature we currently don’t understand.
2. Research topic area (observation)
- In modern science, you always need to do a “literature search”. For this, you’ll need
access to a good library, scientific dat bases on published research and access to
scientific journal publications. This is done since it could just be a phenomenon that
you don’t know about. Others may be fully aware of it, in which case it isn’t really
mystery at all – it was just a mystery to you personally.
- But after you’ve considered what these other scientists have done, you might be
skeptical of their findings or conclusions, or perhaps they overlooked something, and
you’re pretty sure their findings are wrong Maybe you even have your own alternative
explanation.
- This step falls under the “observation” part of the nutshell version of scientific
method.
3. Hypothesis (explanation)
- is a speculative or tentative scientific explanation that must be falsifiable and/or
testable.
- This is the second step in our nutshell version of the scientific method.
- Of course, the explanation may not necessarily be a hypothesis, it might actually be a
theory that already has some supporting evidence. You would know this because
you’ve already done a literature search.
- It could be that an explanation has already been provided by other scientists, or
perhaps it’s a brand-new phenomenon, so you’re going to have to come up with an
explanation yourself, or maybe you just aren’t convinced by the current explanation
and can imagine better tests of it.
- Whatever the case maybe, there is some sort of testable explanation that you can
check to see if it can be supported by evidence, obtained through experiments or
observations, or rejected.
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4. Test with experiment (testing)
- first have to figure out something that should happen, or maybe shouldn’t happen, if
the explanation were true. We might even have to produce a scientific model to make
a prediction of what should happen if true. In which case, based on what we expect
to happen if the explanation were true (or perhaps not happen), we can then carefully
design an experiment, making sure we avoid false confirmation or rejection, to test
our explanation.
- Performing experimental tests of scientific explanations is not free. Research funding
at universities typically comes from grants either from the government or the private
sector.
- But even if the research is funded, the research team must still answer for what they
have achieved with it
- If results are not forthcoming, be it either positive or negative, then the research team
may not get funding in the future. It also means that research groups can’t just
conduct research on whatever they want once funding is awarded.
5. Analyze data (testing)
- This part of the process corresponds to the “testing” step in our nutshell version of
the scientific method.
- It is mentioned here because sometimes the experiment requires gathering data.
- Often the data is measurements from instruments, but it could be survey results, or
perhaps, they are fragments of historical documents or artifacts, or maybe even
camera footage or images.
6. Report conclusion
- This is always a requirement of the funding bodies.
- Many journals have several editors who are world experts in particular areas of
science. So, when you submit your manuscript to the most suitable editor for your
research, you also need to provide several (typically three to five) referees to review
your manuscript before it can be published.
- If your manuscript makes it past the editor, it is sent for peer review
- The peer reviewers then make a recommendation to the editor on what changes you
need to make to the manuscript to allow it to be published in the journal. Or they may
outright reject the manuscript because the work isn’t exciting enough in their opinion,
or its seriously flawed, or there’s something else they take serious exception to.
Based on the recommendations of the reviewers, the editor decides whether to reject
your manuscript or send it back to you to make the appropriate changes as
suggested by the referees.
Communicating Scientific Findings in the Primary Literature
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Which part of the publication process is most crucial for establishing the credibility of the
published work?
- Effective peer review
Concept quiz
"Analyze data" is often seen in the steps making up the scientific method on the web. Which
part of "observe", "explain", "test" was this placed into in the video?
- Test
When publishing research in the primary scientific literature, which part of the publication
process is most crucial for establishing the credibility of the published work?
- Effective peer review
Once scientists have obtained funding for research, can they use that funding to perform
research on anything requested by the public or media journalists? Select the best option
below.
- No - funding granted is for research into the topic funding was granted for.
3. Explain the meaning of accuracy, trueness, precision and uncertainty
illustrating your explanation with examples.
Precision
- High precision means tight grouping of darts, many measurements close in
value to each other. When we have high precision in our measurements, it’s
much easier to figure out what value another measurement would be, or
where another dart would land. (uncertainty low)
- Spread of reading: uncertainty
- So high precision means less randomness in our readings which produces
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low, or small, uncertainty. Thus, a high precision instrument, when measuring
one particular thing, has all of its readings virtually the same.
Uncertainty
- Uncertainty measures the randomness of the measurements
- Uncertainty is a quantitative measure of precision (low precision)
- Measurements not close to each other (random)
Common definition of accuracy
ISO definition of accuracy
Common definition of accuracy
- Accuracy is how close the average of a large number of measurements is from the
true value
- Accuracy include systematic error in the common definition, precision does not enter
into it, does not reflect random error as it only reflects systemic error, accurate but
can also be imprecise (random)
- Poor aim is called systematic error in science
- Uncertainty measures, and precision describes, only the random errors, not the
systematic errors
- Large systematic error means low accuracy in the common definition
- In the common definition of accuracy, an instrument must possess a low, or small,
systematic error. It may have high, or large, random error (high uncertainty)
- Using the common definition, an inaccurate instrument can NEVER give you a true
result because it always has significant systematic error.
ISO definition of accuracy
- Main difference is that ISO calls accuracy, trueness
- Trueness measures how close the true value is from the average of the
measurements
- Trueness in the ISO definition was equivalent to accuracy in the common definition
- Accuracy increases as we move along the diagonal line
- Accuracy means low systematic error and low random error
- An accurate instrument is one that is BOTH precise and true at the same time.
- An accurate instrument will always give you a result close to the true value, even if it
is used to make only one measurement.
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Concept quiz
Uncertainty is a quantitative measure of...
- Precision
Large systematic error means...
- Low accuracy in the common definition
4. Explain the relevance of experimental and control groups and the purpose of
randomized controlled double-blind experiments.
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Double blinding: eliminates additional bias creeping into the outcome of the
experiment from both the experimenter and the subjects.
Blinding the subjects controls for the possibility of suggestibility bias influencing the
outcome of the result (tendency to fill in gaps in memory with information from others
that may well be incorrect)
Subjects should be blinded because of something called the placebo effect.
Placebo-controlled means the subject is blinded, and observer-blinded means the
experimenters are blinded
Randomised controlled: By using random selection, kids entered the experimental
and control groups in a completely impartial and totally objective way. The laws of
chance guarantee that, with enough subjects, the experimental and control groups
resemble each other as closely as possible with respect to any and all variables that
might increase or decrease the likelihood of infection regardless of whether all of
these variables have even been identified.
Concept quiz
What type of bias is eliminated by hiding from the subject whether they have been given a
placebo or the drug?
the tendency to fill in gaps in memory with information from others that may well be incorrect.
- Suggestibility
5. Explain the meaning of the following terms
(a) margin of error
- The margin of error provides us with a range of possible values for the result
of our experiment, instead of just one value. We have this range because
randomness plays a role in the outcome we observe.
- To find margin of error, "confidence level" needs to be specified
- For a specific sample size, as the confidence level increases, the margin of
error increases
- Margin of error is small with large sampe size
(b) confidence level
- A confidence level tells you how confident you are that the experiment you did
is one that contains the true value in the range given by the margin of error
- To be more confident of the experiment that contain the true value within its
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margin of error, we can increase our margin of error so that many of our
experiments contains the true value within their confidence interval
- If confidence interval is too big, but want to keep your confidence at 95%,
take more samples
- To reduce the margin of error by half, take 4 times more samples
- Toss coin: chance of getting correct = 50%
- If a person claim they can tell the outcome, they have to be right more
than 50% of the time
- If the confidence interval includes 50%, we cannot conclude whether
the person can tell the outcome as it can be due to luck
Table of sample size
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Sample size refers to the sample size per control/experimental group
This table is a guide only because its meant for when the % success is not
near 100% or 0%
For example, if your sample size was 50, but you calculated a percentage
success of 90%, you couldn’t have a margin of error of ±14% because you
would get more than 100% as a possible value for the CI.
The point to note here is that the CI, when we’re away from 50% and getting
close to 100% or 0% is smaller than that given in the table and of course it
can’t exceed 100%, nor can it be less than 0%
(c) statistically significant
- When you compare two groups and want to establish a causal link (cause
and effect) between something you did or did not do to the experimental
group, you need to be quite confident that there is a statistically significant
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difference between the experimental and control groups.
You do this by noting if there is a lot of overlap in the margins of error in the
results at a high confidence level, like 95% or better.
The difference is statistically difference at the 95% confidence interval (below
image)
we are certain that administering the Salk vaccine causes a drop in the rates
of polio infection because the difference between the control and
experimental groups was statistically significant at an extremely high level of
confidence.
If there’s a lot of overlap, as we can clearly see here, then it’s quite possible
that the difference between the two groups is simply due to luck, and it’s not
real. The results of this experiment are inconclusive. We cannot be 95% sure
that the difference is real and not just due to chance.
In the above example, the range is from 9% (min) to 37% (max), which is 28% range
(37-9)
The overlap range is 29%-17%=12%
I.e. The number of percentage points of overlap of the two CIs is 12%.
To calculate the overlap: 12%/28%=42% > ⅓
In order to get a more conclusive result, the researchers would need a much larger
sample so they can reduce their margins of error.
Vaccine efficacy formula:
- efficacy is for symptomatic cases not asymptomatic cases
(d) effect size.
- However, just because something is statistically significant, meaning you’re
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95% sure there’s a difference or causal link, doesn’t mean that there’s a
practical difference. That is, the effect observed, the difference that you
measure, might not really be that important
Statistical significance at some confidence level doesn’t necessarily mean
that the difference is large, important, or has a big effect.
6. Apply the 3 rules of thumb to decide if a study has established a statistically
significant difference between an experimental and control group.
(1) if there’s no overlap in the CIs, then the difference is statistically significant at the
95% confidence level.
(2) If the overlap is less than one-third of the range covered by the two CIs, than the
difference could be statistically significant. But the greater the overlap, the less
confident we are that the difference is real.
(3) Finally, if the overlap is more than one-third of the range covered by the two CIs,
the difference is probably not statistically significant.
Sensitivity: true positive
Specificity: true negative
Concept quiz
For a specific sample size, as the confidence level increases, the margin of error...
- Increases (not decrease, because is not the sample size that increase)
Lecture 5 - The Science of Climate Change
Casual model
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Deterministic (there is cause and effect)
William Kingdon Clifford - "it is wrong always, everywhere, and for anyone, to believe
anything upon insufficient evidence. ”
William James - "There are, then, cases where a fact cannot come at all unless a preliminary
faith exists in its coming. ”
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1. Describe the historical development of our understanding as to the nature of
the atmosphere
1. The first suggestion that the atmosphere might be something other than the single
substance as envisioned by the early Greek thinkers, came first from the Italian
polymath, Leonardo da Vinci (1452–1519), and then later by the English chemist and
physiologist, John Mayow (1641–1679), who both suggested that air is composed of
two distinct components: ‘fire-air’that supports combustion and life; and, ‘foul-air’that
does not.
2. In around 1630, the Flemish scientist, Jan Baptiste van Helmont (1580–1644), coined
the term gasto describe the vapours given off when burning wood. He called these
vapours, sylvestre. Today, of course, this gas is known as carbon dioxide.
3. Scottish physician, Joseph Black (1728–1799), who in 1756 proved that the gas
discovered by van Helmont is naturally present in the atmosphere, confirming that
the atmosphere is not a single substance.
- Black's experiments involved heating magnesium carbonate and collecting
the carbon dioxide given off, which he called fixed air
4. The first person to suggest that the atmosphere may play a role in the growth of
plants was Reverend Stephen Hales. He discovered the mechanism by which carbon
returns from the atmosphere to the biosphere.
5. this nourishment of plants is carbon dioxide was finally recognised by the Dutch
scientist, Jan Ingenhousz, in 1796. The study of plant respiration and transpiration in
Vegetable
2. Discuss the discovery of the greenhouse effect and greenhouse gases
- Empedocles of ancient Greece was the first to argue that all matter was composed of
the classical elements of water, earth, air and fire.
- The first person to establish that the atmosphere plays a role in controlling the
climate was a French mathematician, Jean-Baptiste Joseph Fourier.
- Also confounded schoolchildren with his mathematical techniques, but also
for his development of an analytical theory of heat transfer.
- He realised that the Earth itself must radiate (emit (energy, especially light or
heat) in the form of rays or waves), although at wavelengths we cannot see.
- He called this radiation, radiant heat, what we now call infra-red radiation.
- The Earth emits infra-red radiation all the time (So long as an object has a
temperature it emits heat.)
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Fourier made very precise measurements of this radiant heat, and
together with the radiation from the Sun, calculated the Earth’s
temperature to be −18°C, way below the some 15°C we observe
and certainly not conducive for life as we know it.
Fourier realised that this missing something was the atmosphere. The
atmosphere, he surmised, must act as an insulator preventing some of this
radiant heat from escaping to space and returning that radiant heat to further
warm the Earth’s surface.
This was the first formulation of what we now call the greenhouse effect.
The term greenhouse effect first appeared in the work of the Swedish
meteorologist, Nils Gustaf Ekholm, in around 1900. (coin the term)
Importance of water vapour
- The Irish physicist, John Tyndall (1820–1893), is commonly credited with explaining
the greenhouse effect, which underpins the science of climate change.
- To measure the absorption of radiation by various gases, he had to build his own
equipment, the ratio spectrophotometer. This sensitive instrument measured the
extent to which infrared radiation was absorbed and emitted by various gases filling
its central tube. He quickly realised the importance of water vapour in the absorption
of terrestrial radiation.
- Tyndall determined that carbon dioxide is 90 times more effective at
absorbing infra-red radiation than air. He determined methane as being 403
times more effective. He later determined water vapour to be some 16,000
times more effective at absorbing infra-red radiation than pure air.
- Tyndall had discovered in his laboratory that certain gases, including water
vapour and carbon dioxide, are opaque to radiant heat. He understood that
such gases high in the atmosphere help keep our planet warm by interfering
with escaping radiation.
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Eunice Foote identified carbon dioxide as a greenhouse gas a few years before
Tyndall, and also noted its important in controlling the Earth’s surface temperature.
Eunice Foote first to identify carbon dioxide as greenhouse gas
Water vapor is the atmospheric gas that contribute most to the greenhouse effect
Underlying process that explains the greenhouse effect
- The greenhouse effect is due to the absorption of terrestrial infra-red radiation by
gases in the atmosphere, primarily water vapour and carbon dioxide.
3. Recount the discovery of oxygen and its importance in the emergence of chemistry
as a distinct science
- Combustion was completely misunderstood by the alchemists and early chemists. It
was known that air was needed to sustain combustion and to sustain life. It was also
known that when a metal was heated in air it changed and gained weight.
- One of the most famous attempts to explain combustion is due to two Germans: an
alchemist by the name of Johann Joachim Becher (1635–1682); and, a chemist by
the name of Georg Ernst Stahl (1659–1734). They are credited with establishing the
phlogiston theory for combustion.
- Phlogiston theory stated that all combustible materials were made of two
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parts. One part, called phlogiston, was given off when a substance containing
it was burnt.
- The remaining part, the dephlogisticated part, was thought to be the
substance’s true form, or calx. If something gave off a lot of heat, it was
thought to be rich in phlogiston. Growing plants absorb phlogiston from the
air, which is why air does not spontaneously combust and also why plant
matter burns as well as it does. This is an early description of a
biogeochemical cycle.
- Despite the fact that it was known that combustion could only take place in
air, air had no role in phlogiston theory.
English scientist, Robert Hooke, the Dutch scientist, Ole Borch, the Russian scientist,
Mikhail Lomonosov, and the French scientist, Pierre Bayen, produced oxygen in a
variety experiments, but failed to realise that this gas was a chemical element.
The reason for this failure was due to widespread acceptance of the phlogiston
theory. → illusory truth bias
Michael Sendivogius (1566–1636), described a substance contained in air which he
called cibus vitae or ‘food of life’. In experiments he performed between 1598 and
1604, he recognised that this substance is the same as the gas released when
saltpetre is heated. (Saltpetre was the name for the chemical nowadays called
potassium nitrate.)
The secretive Dutch engineer and scientist, Cornelis Jacobszoon Drebbe(1572–
1633), performed similar experiments, and possibly after a lesson from Sendivogius
himself, purified what he called the “spiritous part of it that makes it fit for respiration”.
A third challenger to the title of discoverer of oxygen is perhaps the Swedish
pharmacist, Carl Wilhelm Scheele (1742–1786). He produced oxygen by heating
mercury oxide and various nitrates in experiments between 1771 and 1772. Scheele
called this gas ‘fire-air’ echoing the nomenclature of da Vinci and Mayow.
The person most frequently associated with the discovery of oxygen is the English
theologian, Joseph Priestley (1733–1804). On 1 August 1774, Priestley conducted an
experiment in which he focussed sunlight on mercury oxide in a glass tube which
liberated a gas he called ‘dephlogisticated air’, because it supported combustion and
was totally consumed.
He noted that candles burned brighter in this gas and mice were more active and
lived longer breathing this gas. Priestley published his findings in 1775 in a paper
entitled An Account of Further Discoveries in Air. In his investigations of how the
solubility of carbon dioxide varies with pressure, he discovered carbonation. He
called his fizzy drink “windy water”.
The final challenger most frequently given a right to the claim of discoverer of oxygen
is the French chemist, Antoine-Laurent Lavoisier. He was responsible for naming this
gas ‘oxygen’. He discovered oxygen and was beheaded during the French revolution.
- In noting that the weight gained by a substance in combustion is lost by the
air, he established the Law of Conservation of Mass upon which all modern
chemistry is founded. His theory explained this weight gained that had defied
explanation in the phlogiston theory. He is rightly regarded as the Father of
Modern Chemistry. He is also responsible for the publication of the first
modern chemistry textbook, Traité Élémentaire de Chimie. It is thus that the
study of gases such as carbon dioxide and oxygen and the solving of the
problem of combustion is linked inextricably to the emergence of chemistry as
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a distinct and rational science.
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The three most frequently credited are Scheele, Priestley and Lavoisier
Scheele was the first to isolate this gas, Priestley was the first to publish, but it was
Lavoisier who was first to understand the discovery.
If Occam’s razor is applied to the question of whether Scheele, Priestley, or Lavoisier,
or possibly all three, should be credited with the discovery of oxygen, the result is
quite clear—none of them; oxygen was discovered and isolated more than a century
before their births. Sendivogius isolated oxygen and correctly associated it with that
part of the atmosphere required for life. This is sufficient to give priority for the
discovery of oxygen to Sendivogius.
Anaximenes is a Greek thinker who postulated that all matter was made of the
primordial element air
Concept quiz
Which discoverer of oxygen was the first to truly understand its importance and role in
combustion?
- Antoine-Laurent Lavoisier
4. Explain the greenhouse effect by reference to the absorption of radiation by
greenhouse gases
Calculate greenhouse effect
- Swedish geologist, Arvid Högbom (1857–1940), began attempting to quantify the
natural sources of emissions of carbon dioxide for the purposes of understanding the
global carbon cycle. Högbom found that the estimated carbon production from
industrial sources, primarily from the burning of coal, was comparable to the natural
sources.
- These estimates of Högbom led the Swedish chemist, Svante August Arrhenius
(1859–1927), to consider the effect of changing amounts of carbon dioxide in the
atmosphere. Arrhenius calculated that a doubling of atmospheric carbon dioxide
would raise average global temperatures by 5–6°C using mathematical model. That
estimate made in 1896 is not so very different from most modern attempts to
calculate the temperature change due to increasing carbon dioxide levels. He
thought that it might be beneficial to Earth. The first mathematical model to predict
the effect on global temperature of increasing carbon dioxide was due to Svante
Arrhenius. This had built upon the conceptual work of Joseph Fourier, and the
experimental analysis of John Tyndall and Eunice Foote.
- The first to suggest that increasing carbon dioxide levels might be having an
observed effect was the English engineer and inventor, Guy Stewart Callendar. Like
Arrhenius, though, Callendar thought this warming would be beneficial, delaying a
“return of the deadly glaciers”.
The Keeling Curve
- The most important set of data ever recorded in the history of climate change is the
data collected from the Mauna Loa Observatory in Hawaii some 3,000 metres above
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sea level. Charles Keeling is famous for his measurements of carbon dioxide at the
Mauna Loa Observatory in Hawaii In 1958, the American scientist, Charles David
Keeling (1928–2005), received funding from the National Science Foundation to
collect carbon dioxide samples at this base. By 1961, Keeling produced data showing
that carbon dioxide levels were rising steadily in what later became known as the
Keeling Curve—a data set that continues to this very day. The data was so
concerning that by 1963 the Foundation used Keeling’s research in its warning of
rapidly increasing amounts of heat-trapping gases.
Restoring the quality of our environment
- In 1965, U.S. President Lyndon B. Johnson’s Science Advisory Committee published
their landmark report, Restoring the Quality of our Environment. This report warned
of the harmful effects of fossil fuel emissions
- The committee used the recently available global temperature reconstructions and
carbon dioxide data from Keeling to reach their conclusions. They declared the rise in
levels of atmospheric carbon dioxide to be the direct result of burning fossil fuel. The
committee concluded that human activities were sufficiently large to have significant,
global impact—beyond the area the activities took place.
Predicting the future of climate change
- Following the advent of computer models, the American scientist, James Hansen
(1941–), published a study in Science in 1981. The results from this study were
subsequently found to accurately predict the 0.6°C temperature rise between 1984
and 2017.
- In 1988, the same James Hansen, now Director of the NASA Goddard Institute for
Space Studies 61, was called before the U.S. Congress to give testimony. Hansen
told the congressional committee that it was 99% certain that the warming trend was
not a natural variation but caused by a build-up of carbon dioxide and other artificial
gases in the atmosphere.
What is the difference between the greenhouse effect and global warming?
- Without greenhouse effect, we would all be dead.
- The greenhouse effect is the name given to the process that causes the surface to
be warmer than it would have been in the absence of an atmosphere.
- Global warming is the name given to an expected increase in the magnitude of
the greenhouse effect, whereby the surface of the Earth will be inevitably hotter
than it is now.
Metaphor
- A common metaphor for the greenhouse effect is that the atmosphere acts like a
blanket. Blankets do not behave in the same way as greenhouse gases though.
- Blankets keep us warm because they suppress convection. Heat from your bodies is
not able to escape because of the blanket. The atmosphere enables convection.
- The metaphor works because more blankets means warmer person; more
greenhouse gases means warmer planet.
- Unfortunately, there are other emissions to the atmosphere that do not follow this
metaphor. If we increased the emissions of sulphate aerosols, say through volcanic
eruptions, the planet would cool not warm. This was observed following the eruption
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of Mount Pinatubo in 1991.
It is ironic that we call the effect by which the Earth is warmed by the presence of
gases like water vapour and carbon dioxide in the atmosphere the greenhouse effect.
The reason why is because greenhouses behave in exactly the same way as
blankets, the glass inhibits convection and prevents the exchange of air between
inside and outside.
For which two processes in the atmosphere does the blanket metaphor NOT work?
- More sulphate aerosol means cooler Earth surface
- The atmosphere enables convection
(Sulphate aerosols scatter radiation back to space, thus more aerosol leads to a cooler
Earth. Blankets inhibit convection whereas the atmosphere enables convection.)
Why is the Earth warmer?
- The surface of the Earth is warmer than it would be in the absence of an atmosphere,
because it receives energy from two sources: the Sun and the atmosphere.
Which two energy sources are most important for warming the Earth’s surface?
Sun, atmosphere
Which two gases are the most important greenhouse gases in the Earth’s atmosphere?
- Carbon dioxide, water vapour
Mathematical Model to estimate Earth’s temperature
- What do we mean though when we say the Earth is a black body? The Earth is
clearly not black. Referring to an object as a black body is a technical description; it
means the object absorbs all radiation and, assuming the object is in thermal
equilibrium, emits a spectrum of radiation determined by its temperature alone.
- The fraction of incoming solar radiation that is reflected is often referred to as the
Earth’s albedo, and is denoted by the symbol, A.
- When we do this, we find that the temperature of the Earth’s surface is 255 K. This is
equivalent to −18°C. The same temperature calculated by Fourier. As noted
earlier, this would make the Earth an uninhabitable environment. The planet would be
a snowball.
- It should be noted that if we were to attempt to measure the Earth’s average
temperature from space, this value of −18°C is the temperature that would be
measured—it is often referred to as the planet’s effective temperature.
1370 W m⁻² - is the energy per square metre arriving earth every second
If Albedo = 0.2:
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Square root 4 [1370 x (1 - 0.2)/(5.67 x 10^8 x 4] = 264K
If we assume the Earth is behaving as a black body, then the energy emitted per unit area is
given by the Stefan–Boltzmann law. That is the energy per unit area, also known as the
intensity, is equal to the Stefan–Boltzmann constant, σ, times the fourth power of the
temperature.
5. Estimate the greenhouse effect using the single-layer atmosphere model.
Radiation transmitted by the atmosphere
- The first thing to note is that the atmosphere cannot absorb and radiate at all
wavelengths and so cannot be treated as a black body.
- At visible wavelengths, at around 0.5 microns, the atmosphere is largely transparent,
that is it lets radiation in the visible to pass through without being absorbed.
- At shorter wavelengths in the ultraviolet, particularly below 0.3 microns, the
atmosphere is opaque, that is it absorbs all radiation at these wavelengths.
- The reason for this is the presence of oxygen and ozone in the atmosphere. The
absorption prevents potentially mutagenic radiation from reaching the biosphere.
- At infra-red wavelengths, between 6 and 25 microns, the atmosphere is far more
opaque. It should be noted that at some wavelengths in the infra red absorption is not
possible, because there are no molecules present in the atmosphere that can absorb
such wavelengths—this leads to the presence of so-called atmospheric windows.
- Radiation emitted by the Earth’s surface at wavelengths in an atmospheric window
will escape unhindered to space.
- This discussion of the radiative properties of the Earth’s atmosphere predicts how the
atmosphere will interact with the various radiations passing through it. Solar radiation
at visible wavelengths will largely pass through the atmosphere unhindered.
- This radiation will be absorbed by the Earth’s surface. The Earth's surface will then
emit radiation at wavelengths dependent on its temperature, that is in the infra red.
- The atmosphere will largely absorb all this terrestrial radiation. The atmosphere will
also emit radiation dependent on its temperature, but it will not be able to emit at all
wavelengths.
- This radiation is emitted in all directions. The component directed towards the Earth’s
surface acts as an additional source of energy and results in the elevated Earth
surface temperature.
Atmosphere model
- We noted that the spectral distribution, that is the intensity of radiation emitted by the
black body at different wavelengths, is simply determined by its temperature.
- Wien’s law describes this relationship; it states that the wavelength of peak of the
spectral distribution is inversely proportional to its temperature.
- The simplest way to extend our mathematical model to include an atmosphere is to
treat the atmosphere as a single layer of uniform temperature.
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6.
F_a → flux from atmosphere
- atmosphere radiates energy and does so back to space and back towards the
earth surface
Incoming
F_s → solar flux
- Solar flux or concentrated sunlight is a measure of how much light energy is
being radiated in a given area
- Takes into account of Earth’s albedo
T_s → solar transmittance
- we need to account for the absorption of radiation by the atmosphere
- Hence, transmittance as the fraction of radiation that is not absorbed, hence it
reduce the solar flux
Leaving as earth emits radiation
F_g → terrestrial flux/ground flux
- earth’s surface temperature
T_g → terrestrial transmittance
- reduce the terrestrial flux leaving earth because the earth’s atmosphere
absorb radiation
- Terrestrial flux that gets through the atmosphere and escape into space
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To calculate the terrestrial flux, we need representative values for the solar and
terrestrial transmittances. Appropriate estimates are 0.8 for solar transmittance and
0.1 for terrestrial transmittance. These numbers mean that 80% of solar short-wave
radiation gets through the atmosphere without being absorbed, but only 10% of
terrestrial long-wave radiation gets through the atmosphere without being absorbed.
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Terrestrial flux is proportional to the fourth power of the Earth’s surface temperature.
The greater the terrestrial flux, the greater the Earth’s temperature.
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According to the single-layer atmosphere model, surface temperature decrease if
albedo (proportion of radiation that is reflected) increases
When albedo decrease, solar flux is smaller, this change propagates through the
entire earth system resulting in smaller ground flux and ultimately smaller earth
surface temperature
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If we decrease the transmittance of terrestrial radiation (t_g), for example if we were
to increase the amount of greenhouse gases absorbed in the atmosphere, then this
expression would lead to an increase in the terrestrial flux (f_g) and thus an increase
in the Earth’s surface temperature.
Vice versa, if t_g increase, the earth’s temperate (f_g) decrease because more
radiation/ground flux (t_g) is escaped to space
The Earth’s surface is 34 K warmer than it would be without an atmosphere. This is
the magnitude of the greenhouse effect.
Lecture 6 - Establishing the Scientific Consensus on Climate Change
1. Describe the history of the establishment of the scientific consensus on
climate change including the role played by the IPCC
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The IPCC is an intergovernmental body of the United Nations mandated to provide
objective scientific information relevant to understanding human-induced climate
change, its natural, political, and economic impacts and risks, and possible response
options.
Published 3 reports. In these assessment reports, the systematic review of the
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scientific literature revealed that the scientific consensus was that human-induced
climate change through burning fossil fuels was being identified in the observational
record.
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Intergovernmental Panel on Climate Change, or IPCC, published its Sixth
Assessment Report in August 2021. In that report, it is noted that temperatures have
risen by more than 1°C since the 1850–1900 global average, and that it is
“unequivocal (no doubt) that human influence has warmed the atmosphere, ocean
and land”. It describes the ways in which Earth’s climate has changed due to human
activity as “unprecedented” (never known before) in the previous hundreds of
thousands of years, with some of the changes as now being inevitable and
“irreversible". This is the current scientific consensus.
IPCC first assessment report (1990)
- It published its First Assessment Report in 1990 in which they stated, “global mean
surface air temperature has increased by 0.3 to 0.6°C over the last 100 years”. They
further noted that “The size of this warming is broadly consistent with predictions of
climate models, but it is also of the same magnitude as natural climate variability”.
IPCC second assessment report (1995)
- However, in their Second Assessment Report published in 1995, the IPCC noted
that, “The balance of evidence suggests a discernible human impact on global
climate”. In the half decade between the two reports, the scientific consensus had
shifted from an understanding that the greenhouse effect is well understood,
greenhouse gases are increasing (due largely to human activity), and therefore
should lead to significant global warming (though lack of understanding limited
specific regional predictions), to a greater understanding (despite continuing
uncertainties) that global warming continues and is most likely due to human activity.
IPCC third assessment report (2001)
- In the Third Assessment Report published in 2001, the IPCC stated that, “Human
activities…are modifying the concentrations of atmospheric constituents…that absorb
or scatter radiant energy. [M]ost of the observed warming over the last 50 years is
likely to have been due to an increase in greenhouse gas concentrations.”
Arguing from authority
- Scientific consensus is achieved when the great majority of scientists of a given field
agree upon a position based on a large amount of evidence.
- Consensus is not just a general agreement, but is dependent on the expertise of the
scientists in question and is based on the accumulation and verification of evidence.
- A scientific community is a prerequisite for the emergence of a consensus.
- emergence of the Royal Society of London as an example of a scientific community.
Corn about global warming
- Concern about global warming was first voiced by Guy Callendar.
- Suggested that the increase in carbon dioxide may account for the observed slight
rise of average temperature. Uncertainty around water vapour. But they argued that
water vapour is a greenhouse gas and that there is so much more water vapour than
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carbon dioxide. Scientists were sceptical that small increases in carbon dioxide could
have a big effect.
Atmospheric windows
- You can see that water vapour and carbon dioxide do not absorb at the same
wavelengths. Importantly there are wavelengths at which water vapour absorbs very
little, but carbon dioxide absorbs greatly. Increases in carbon dioxide will thus
significantly increase the absorption of infra-red radiation at these wavelengths and
ultimately affect Earth surface temperatures. So water vapour will not overwhelm the
absorption due to carbon dioxide.
On the need for the measurement of carbon dioxide
- Among the first to recognise that there was a need to return to the work of Callendar
were Roger Revelle and Hans Suess.
International geophysical year
- The International Geophysical Year that lasted from 1 July 1957 until the end of 1958
was crucial in bringing together scientists from across the globe to study many issues
of geophysical concern, including climate change. It was as part of the International
Geophysical Year that Charles Keeling received the funding, pushed for by Revelle
and Suess, to measure carbon dioxide at Mauna Loa in Hawaii.
In Hawaii
- Keeling’s data showed that between 1958 and 1965, CO₂ concentrations had risen
by some 1% or 3 parts per million by volume (or ppmv). These data were greatly
concerning to the scientific community.
President’s Science Advisory Committee
- Revelle and Keeling were asked to chair the President’s Science Advisory Committee
that published the report, Restoring the Quality of our Environment, that we
mentioned in the last lecture. In that report, the authors warned that, “By the year
2000 there will be about 25% more CO₂ in our atmosphere than at present [and] this
will modify the heat balance of the atmosphere to such an extent that marked
changes in climate…could occur."
Informing public policy
- Responding to this report, President Lyndon Johnson declared in a special message
to the U.S. Congress, again in 1965, that, “This generation has altered the
composition of the atmosphere on a global scale through …a steady increase in
carbon dioxide from the burning of fossil fuels”. Here, the U.S. President was
reporting the scientific consensus from his Science Advisory Committee.
- This is one of the important roles that scientific consensus plays in society; it helps to
inform public policy.
- And indeed in the 1970s in the U.S. the impact of rising carbon dioxide on climate
was informing national policy in terms of energy, national security and the economy
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Achieving consensus
- in an evaluation of the evidence for CO₂-induced climate change, the National
Academy of Sciences, the premier science academy in the U.S. whose membership
is considered one of the highest professional honours, released a report that stated.
- This was a consensus not just of the conceptual understanding by which carbon
dioxide influences Earth surface temperature, but it was a consensus of expectation:
that if we continue to burn fossil fuels, then climate change, including increased Earth
surface temperatures, will result.
- Have we identified when the scientific consensus on climate change was
established? Yes and no. We have established a consensus that burning fossil fuels
lead to climate change, but there was not a consensus about when the climate
change will happen.
Natural climate variability
- Determining when climate change would be detectable required sophisticated climate
models: mathematical descriptions of the climate programmed into computer models.
- The key to knowing when climate change would be detectable was estimating the
natural climate variability.
Concept quiz
Which word was NOT used in the IPCC Sixth Assessment Report to describe the humaninduced climate change?
- Expected
At what wavelengths is carbon dioxide most effective at absorbing terrestrial radiation?
- atmospheric windows in the infra-red region
Who was the first to suggest that increases in carbon dioxide through the burning of fossil
fuels had led to an observed increase in Earth surface temperature?
- Guy Callendar
2. Articulate the difference between weather and climate, and between the
greenhouse effect and climate change
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Weather can be thought of as a combination of temperature, humidity, precipitation,
cloudiness, visibility, and wind, that we might experience at a particular location in the
short-term. Weather reflects the short-term conditions of the atmosphere.
Climate, on the other hand, describes the typical weather conditions in an entire
region for a very long time
Climate is what we expect, and weather is what we get.
Climate change includes both the global warming driven by human induced
emissions of greenhouse gases, and the resulting large scale shifts in weather
patterns.
Global warming as being the cause, and climate change as being the effect
The greenhouse effect is the name given to the process that causes the surface to
be warmer than it would have been in the absence of an atmosphere. (absorption of
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greenhouse gases)
3. Outline how proxy methods used in the reconstruction of past temperatures
Proxy methods
- it is sometimes necessary to study a variable which cannot be measured directly
- This can be done by proxy methods, a variable which correlates with the variable of
interest is measured, and then used to infer the value of the variable of interest.
- Proxy methods are of particular use in the study of the past climate, beyond times
when direct measurements of temperatures are available.
- Proxy methods use data that correlate with the variable of interest
- In the study of past climates, or paleoclimatology, scientists use proxy methods to
reconstruct past climate conditions
Dendroclimatology
- The most well-known proxy method in temperature reconstructions is
dendroclimatology in which the width of tree rings is used to determine past climate.
- Tree rings are wider when conditions favour growth, and narrower when times are
difficult. Using tree rings, scientists have estimated many local climates for hundreds
to thousands of years previous.
- By combining multiple tree-ring studies, in a process known as cross dating in which
after establishing the chronology from a living tree chronology is extended back in
time by matching the inner rings with the outer rings of dead wood samples,
scientists have estimated past regional and global climates. One of the particular
advantages of tree-ring studies is the ease with which tree rings can be dated.
Coral reefs
- Another proxy comes from studying coral reefs. The bands in the coral’s shell can
change in thickness with changes in temperature, water clarity, or nutrient availability,
so while each band can record the season’s climate, the interpretation of the record
depends on how the three factors are related.
- Cool water rising from the ocean floor brings extra nutrients in many areas, so the
shells are often thicker when the water is cool.
Ice cores
- Ice cores are one of the best available climate proxies, providing a fairly highresolution estimate of climate changes into the deep past.
- An ice core is a core sample that is typically removed from an ice sheet or a high
mountain glacier.
- Since the ice forms from the incremental build-up of annual layers of snow, lower
layers are older than upper, and an ice core contains ice formed over a range of
years.
- Since scientists cannot directly measure temperatures from ice cores, they have to
rely on measuring the oxygen isotope, oxygen-18, in water, which is correlated with
temperature, if somewhat imperfectly.
Vostok Station ice-core temperature record
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This record reveals past ice ages and interglacial periods. The last interglacial period
ended about 120,000 years ago. Thereafter, we had an ice age that itself ended
about 11,500 years ago. Since then, Earth has been in an interglacial period called
the Holocene.
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Data taken from trees, coral reefs, and ice cores all confirmed that the recent
temperature increase is unprecedented in the last 800,000 years.
This claim would stand against the third element of the BDTK—Is the claimant
providing positive evidence? scientists had attempted to determine whether the
observed increase was simply a result of natural variability, or changes in solar or
volcanic activity. However, the evidence to support such ideas is simply not there.
The only explanation that scientists have failed to disprove is that the increase in
temperature is due to the increase in greenhouse gases, in particular, carbon dioxide.
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Concept quiz
Which of the following proxies use the widths of bands or rings to determine past
temperature?
- Tree rings and coral bands
How far back can the Vostok Station ice core be used to reconstruct past temperatures?
- 420,000 years
4. Recognise the difference between the public perception of the scientific
consensus on climate change and that of the scientific community
Gallup environment poll
- The Gallup environment poll showed that in 1997 only 48% of the U.S. public
believed that “most scientists believe that global warming is occurring”.
- However, this figure rose sharply such that some 61% of the U.S. public believed this
by 2001. This number rose still further to 65% by 2006 where it stayed in 2008, but
dropped dramatically to 52% by 2010. The number in 2021 is still only 68%.
Consensus in the scientific literature
- The first attempt to determine the level of scientific consensus in the published, peerreviewed scientific literature was conducted in 2004 by Naomi Oreskes, the co-author
of the book ‘Merchants of Doubt’.
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Oreskes found that in the 928 papers published in the 10 years between 1993 and
2003 that talked about global warming not one rejected the scientific consensus.
Indeed in a later study of the scientific literature by John Cook and co-authors in
2013, that in a survey of 11,944 abstracts from peer-reviewed journals 97.1% agreed
with the scientific consensus that human-induced climate change is real and
happening.
There is a disconnect between the public perception of the level of consensus
present among scientists studying climate change and the consensus among
scientists themselves. This scientific consensus is represented in the reports of the
IPCC and is the position of every national and international scientific body.
Concept quiz
Who was the first to determine the level of scientific consensus in the published, peerreviewed scientific literature?
- Naomi Oreskes
When was the Second Assessment Report of Intergovernmental Panel on Climate Change
(IPCC) published?
- 1995
(third report: 2001, first report: 1990)
5. Explain how the scientific consensus on climate change was established.
There are a number of questions that need to be answered:
● First, does the observational record show that average global temperatures are
rising?
● Second, is the temperature rise unusual?
● Third, are atmospheric greenhouse gas concentrations also increasing?
● Fourth, is the rise in carbon dioxide due to the burning of fossil fuels?
● And finally, do we understand human-induced climate change?
temperature rising
Instrumental temperature record
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The NASA record tends to run slightly higher than the Japanese record, while the
United Kingdom and NOAA records are usually in the middle.
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Getting an accurate measurement of air temperature across the entire planet is not
simple. Ideally, scientists would like to have thousands of standardised weather
stations spaced evenly all around the Earth’s surface.
Beyond these issues of coverage, the surface temperature record also goes through
a series of adjustments to correct for issues, such as missing data, changes in
instrumentation, movement of stations, and human or technical error.
This process is known as homogenisation and, despite being a well-understood
scientific practice, has been used by some climate-sceptic commentators as
evidence that scientists are “fiddling” the data to overstate the amount of warming
we’ve seen.
Berkeley Earth was a project set up in 2010 with the goal of addressing concerns
from outside the climate science community regarding global warming and the
instrumental temperature record. Its founder, Richard Muller is a highly respected
physicist, but was a climate skeptic.
So has there been a temperature rise since pre-industrial times? Well the figure we
showed previously had as a baseline the 1951–1980 average and showed a
temperature anomaly of between 0.75 and 1°C depending on the dataset. Arguably
the effect of industrialisation is already present in the baseline average. If instead we
use the 1850–1900 period as a proxy for pre-industrial temperatures, then the
temperature rise is even greater. The Berkeley Earth dataset here gives a
temperature rise a little in excess of 1.2°C. The IPCC in the Sixth Assessment Report
reports this temperature rise as 1.1°C.
Unprecedented (never done or known before)
- IPCC Sixth Assessment Report states, that the observed warming since 1850 is
“unprecedented in more than 2000 years”
- current temperatures have certainly not been witnessed in the last 100,000 years.
However, what is stark about the long-term temperature record is how unusual the
recent rise in temperature is. Although temperature rises of 10°C characterise the
transition from glacial to interglacial periods. The rate of the temperature increase
seen recently is far more rapid than has been seen in the last 800,000 years.
Concomitant Rise in Greenhouse Gases
Carbon
- Carbon dioxide is an important trace gas in Earth's atmosphere. It is an integral part
of the carbon cycle, that is the biogeochemical cycle in which carbon is exchanged
between the Earth's atmosphere, oceans, soil, rocks and biosphere.
Keeling Curve
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The dataset we introduced in the last lecture was that from the Mauna Loa
observatory in Hawaii. A dataset started by Charles Keeling and which now bears his
name. The Keeling curve shows atmospheric CO₂ concentrations rising from 315
ppmv in 1958 to in excess of the 415 ppmv levels seen today.
Colors of life
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shows the global biosphere in the background and the corresponding carbon dioxide
graph in the foreground. The biosphere is represented as phytoplankton
concentrations over the ocean and the vegetation index over land. The carbon
dioxide concentrations are from Mauna Loa in Hawaii.
Perhaps more poetically, this shows the Earth breathing, in and out, once per year
Ice-core carbon dioxide record
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Did this upward trend though begin with the Industrial Revolution? We can go further
back in time by using the ice-core record.
Carbon dioxide concentrations, and indeed the concentrations of other gases, can be
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determined from the composition of air in bubbles trapped in the ice.
This figure shows carbon dioxide concentrations during the last 800,000 years. We
can clearly see variations in carbon dioxide throughout the Pleistocene from lows of
about 180 ppmv, during deep glaciations, to 280 ppmv during interglacial periods.
Pre-industrial concentrations are confirmed to be 280 ppmv.
The current concentrations of carbon dioxide have not been seen in at least the last 2
million years. The rate of increase of carbon dioxide since the Industrial Revolution is
also profoundly unprecedented.
Methane and nitrous oxide
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Similar records of other greenhouse gases tell the same story.
Methane (CH₄) concentrations have increased from pre-industrial values of about
600 ppbv to levels over 1800 ppbv—a three-fold increase.
Nitrous oxide (N₂O) concentrations have increased from some 270 ppbv to 338 ppbv
today.
It is clear that the increase in temperatures since the beginning of the Industrial
Revolution has been accompanied by increases in the concentrations of greenhouse
gases. The current concentrations of greenhouse gases have not been witnessed in
at least the last several hundred thousand years. The rapidity of these increases has
also never been seen in our record of greenhouse gas concentrations.
Anthropogenic (originate from human) or Natural
- The next question that we need to answer is how can we be sure that the rise in
carbon dioxide is due to the burning of fossil fuels? It requires us to think deeply
about the carbon cycle.
Global carbon cycle
- The global carbon cycle describes the movement of carbon between the carbon
reservoirs in the Earth system.
- Burning fossil fuels increases the exchange flux of carbon into the atmosphere
resulting in an increase in the atmospheric carbon reservoir.
- The greatest physical reservoir of carbon is not atmospheric carbon dioxide, but
instead is located in the Earth’s crust and is not easily accessible to biological
organisms.
- The source of virtually all carbon found in living organisms is CO₂ either in the
atmosphere or dissolved in water. The global carbon cycle can be viewed as a series
of reservoirs of carbon in the Earth System, which are connected by exchange fluxes
of carbon. An exchange flux is the amount of carbon which moves between
reservoirs each year.
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Before human activities, such as land use changes and industrial processes, had a
significant impact, the global carbon cycle was roughly balanced. However, CO₂ has
increased by almost 50% from around 280 ppmv in 1750 to the current levels of over
415 ppmv.
Balancing the carbon budget
- This accountancy of the carbon budget is difficult and fraught with uncertainty. The
studies to estimate the exchange fluxes are some of the most challenging in Earth
science. Not surprisingly many climate change deniers have argued that these
studies are flawed and do not show that burning fossil fuels has increased the
atmospheric carbon reservoir.
Carbon-14
- Scientists have been able to conclusively show that the increase in carbon dioxide in
the atmosphere is due to burning fossil fuels, and they did this indirectly by
measuring the atmospheric concentrations of carbon-14.
- Carbon-14 is formed in the upper atmosphere through the impact of cosmic radiation.
- The carbon-14 is eventually oxidised to carbon dioxide and through photosynthesis it
is incorporated into the biosphere. Anything made of organic material will have
carbon-14 present in its structure.
- This carbon-14 is radioactive and decays with a half-life of some 5,730 years (time
required for half of carbon-14 to decay). If we know the amount of carbon-14 as a
function of time in the past, then we can use measurements of carbon-14 to date
materials. This is the basis of radiocarbon dating.
Suess effect
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Hans Suess, who we discussed earlier, realised that burning fossil fuels would dilute
the amount of carbon-14 present in the atmosphere.
Suess recognised that the influence of this dilution would affect the accuracy of
radiocarbon dating.
More recently, the Suess effect has been used to argue that the rise in carbon
dioxide in the atmosphere is due to burning fossil fuels.
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The mechanism for this drop was not radioactive decay, after all carbon-14 has a
half-life of 5,730 years and so radioactive decay would not be noticeable on the
timescale in this figure, instead the mechanism was due to the dilution through the
burning of fossil fuel.
The rate of decay can be shown to match exactly that which would be expected
given the increase in atmospheric carbon dioxide through the burning of fossil fuels.
There is simply no other mechanism that can explain this decay in carbon-14.
Anthropocene
- Earth has been in an interglacial period called the Holocene. transition from the
Holocene to the current period in which humans have become a dominant force of
global environmental change.
- Paul Crutzen cointed the term Anthropocene to denote this period.
On the Nature of Scientific Understanding
Scientific understanding
- The final question that needed to be answered to convince the scientific community
was to show that we understand human-induced climate change. Indeed, this is one
of the central aims of the IPCC.
- Modelling global surface temperatures
- These models represent our best understanding of climate science and
human-induced climate change in particular. They offer convincing evidence
that we do understand human-induced climate change with a great deal of
fidelity.
- The model simulations that exclude human influence through increasing
greenhouse gases, and only include natural drivers, show no warming across
the entire period from 1850 to the present day.
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In the figure shown here from the Sixth Assessment Report of the IPCC, we can see
the observed changes in global surface temperature over the past 170 years,
represented by the black line, relative to an 1850–1900 baseline.
This is compared to the CMIP6 climate model simulations of the temperature
response to both human and natural drivers, represented in brown, and to only
natural drivers, that is solar and volcanic activity, represented in green. Solid
coloured lines show the multi-model average, and coloured shades show the very
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likely range of simulations.
Note that the brown solid line, representing the average of all the model simulations
that include both human and natural drivers, closely follows the observed
temperature record indicated by the black line.
The model simulations that exclude human influence through increasing greenhouse
gases, and only include natural drivers, show no warming across the entire period
from 1850 to the present day. The model simulations argue that it is impossible to
reproduce the observed warming in global surface temperatures without including the
increase in greenhouse gases due, in the case of carbon dioxide, to the burning of
fossil fuels.
The CMIP6 is the sixth iteration of the Coupled Model Intercomparison Project.
CMIP6 consists of simulations from around 100 distinct climate models produced
across 49 different modelling groups. These models simulate the physics, chemistry
and biology of the atmosphere, land and oceans in great detail, and require some of
the largest supercomputers in the world to generate their climate projections.
The objective of the Coupled Model Intercomparison Project is to better understand
past, present and future climate changes arising from natural, unforced variability or
in response to changes in radiative forcing in a multi-model context.
These models represent our best understanding of climate science and humaninduced climate change in particular.
They offer convincing evidence that we do understand human-induced climate
change with a great deal of fidelity.
Which of the following have negative radiative forcing (i.e., the event leads to more radiation
leaving the Earth system than entering the Earth system)?
- Volcanic eruptions releasing sulphate aerosols
- Planting a billion hectares of new forest
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It is in answering the questions set earlier, that is that global temperatures are rising,
that this rise is unusual, that greenhouse gases are also rising, that this rise in
greenhouse gases is due to human emissions, and that our models quantitatively
reproduce the observed warming, that the scientific community reached the
consensus position that human-induced climate change is happening.
Concept quiz
Which of the following is NOT one of the four major keepers of records on global
temperature?
- Berkeley Earth
Which agency's instrumental temperature record has the greatest global coverage?
- National Aeronautics and Space Administration
In the Pleistocene, what were the levels of atmospheric carbon dioxide during deep
glaciation?
- 180 ppmv
What statement best describes the change in atmospheric methane concentrations since the
Industrial Revolution?
- Methane concentrations have tripled (600 ppbv to 1800 ppbv)
How many petagrams of carbon reside in the reservoir 'dissolved organic carbon'?
- 700 pGC
If a timber remnant from an ancient sailing vessel is retrieved and tested for carbon-14, and
the amount of carbon-14 is half of the amount found in current wood, how old is the ancient
sailing vessel?
- 5,730 years old
Which of the following statements about modelled global average surface temperatures is
true?
- Model simulations that include both anthropogenic (resulting from the influence of
human beings on nature) and natural factors reproduce the observed global average
surface temperatures
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How many model simulations are included in the Coupled Model Intercomparison Project 6?
- 100
Which two of the following processes represent flows of carbon (i.e., exchange fluxes of
carbon) between the atmosphere and the biosphere?
- Respiration
- Photosynthesis
(Respiration is one of the means by which carbon is returned from the biosphere to the
atmosphere. Photosynthesis is one of the means by which carbon is returned from the
atmosphere to the biosphere.)
Which two of the following are reasons why a scientific consensus on climate change has
been reached?
- The consensus position is supported by ninety-seven percent of research papers in
the field
- The observational record shows that average global temperatures are rising
- Variations in natural forcings, solar and volcanic, do not explain the observed
increase in temperature.
Which two continents have the longest reliable temperature records?
- North America
- Europe
(Instrumental temperature measurements have been made regularly in Europe and North
America for over 100 years.)
Lecture 7 - On the Mongering of Doubt
1. Explain why and how doubt about climate change permeated both political and
public spheres
Affirmation of scientific consensus
- we noted the affirmation of the scientific consensus on human-induced climate
change by President Lyndon Johnson in his special message to the US Congress in
1965.
- This affirmation of the scientific consensus by U.S. Presidents became a tradition.
President George H. W. Bush (1924– 2018) affirmed this consensus when he signed
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the United Nations Framework Convention on Climate Change at the Earth Summit
in Rio de Janiero in 1992.
Why, some 30 years after the scientific consensus on climate change was reached, there
are no binding targets or timetables for greenhouse gas emissions reductions.
- in the words of President Bush himself, “The American way of life is not up for
negotiations. Period.”
- it is easy for governments to say ok yes climate change bad, but difficult for them to
say ok lets sign this contract that we must all go 100% green by 2030.
“Technical poppycock”
- John Sununu has a PhD in mechanical engineering from the MIT and was an
Associate Professor at Tufts University between 1966–1982, before being elected the
75th Governor of New Hampshire (1983–1989).
- But despite having no training in climate science, Sununu felt that he was qualified to
pass judgement on the work of James Hansen, the Director of NASA's Goddard
Institute for Space Studies, who had famously testified to the US Congress in the
summer of 1988 just prior to Bush being elected President.
- Sununu described Hansen’s work as “technical poppycock.” The science underlying
the link between global warming and the combustion of fossil fuels, Sununu believed,
was insufficient to warrant government action or societal expense.
- John Sununu, the Chief of Staff in the George H. W. Bush White House, attempted to
undermine the work of climate scientists and ultimately the international community in
fighting climate change. He argued from authority that global warming was
“poppycock”.
- He is not a climate science expert, but used his authority as a retired associate
professor (in mechanical engineering) to argue his case. (How reliable is the source
of the claim?)
Scientist says budget office altered his testimony
- This alerted Sununu who then had the testimony heavily edited. Hansen described
these edits as leaving his testimony “meaningless”.
- Although this effort at censorship was exposed and ultimately proved embarrassing
for the Bush administration, Sununu’s efforts to oppose climate change policy and
any regulations limiting carbon dioxide emissions that he thought would stifle
economic growth continued.
The Noordwijk declaration
- In November 1989, 400 officials from 65 countries met in Noordwijk in the
Netherlands to discuss a framework for a global treaty on greenhouse gas emissions.
- Most of the delegations were prepared to endorse the Dutch proposal to freeze
emissions at 1990 levels by 2000, and a reduction of 20% by 2005.
- Sununu had a climate change sceptic appointed to the US negotiating team. His
appointee was given orders to prevent any U.S. commitment to limits. No agreement
was forged.
"Frankly, that's about where we are today"
- In a 2018 interview for his article “Losing Earth: The Decade We Almost Stopped
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Climate Change”, Nathaniel Rich asked Sununu whether he felt responsible for killing
the attempt at a global climate accord.
His answer was both cynical and accurate. “It couldn’t have happened,” he told Rich,
“because frankly, the leaders of the world at that time were at a stage where they
were all looking at how to seem like they were supporting the policy without having to
make hard commitments that would cost their nations serious resources.” Sununu’s
next sentence is chilling. “Frankly, that’s about where we are today.”
The rest of the Bush presidency, as indicated by the failure of the 1992 Earth Summit
in Rio to commit to binding limits on carbon dioxide emissions, continued this
doctrine and the rest of the world followed suit.
To say that this story was a failure to listen to the science and the climate science
experts, and the hubris of the powerful to believe they are right because they have a
PhD, would be to simplify and ignore the other socio-economic and geopolitical
considerations at play, but it is a story that needs to be heard and understood.
It further illustrates the importance of questioning the authority of a source. To ask
yourself, what are the qualifications of the source?
How to influence the public
- Why and how did this doubt, present in the opinions and beliefs of politicians and
officials at the highest levels of government, permeate into the public arena?
- These are the questions that Naomi Oreskes and Erik Conway sought to answer in
their book.
Rise of the doubt mongers
- Oreskes and Conway are quick to identify the role of a non-profit conservative think
tank, the George C. Marshall Institute. This institute was established in 1984 with a
focus on science and public policy. The founders of this institute were an interesting
bunch. They were all physicists who made their names in the Cold War working on
U.S. rocketry and weapons programmes.
- Robert Jastrow (James Hansen’s boss)
- William Nierenberg (Charles Keeling’s boss)
- Frederick Seitz
Star wars
- Having worked together on an advisory panel to the Reagan administration on the
Strategic Defense Initiative, colloquially referred to as the Star Wars initiative, they
decided to create the Marshall Institute to continue this work to defend the Strategic
Defense Initiative in the face of what they believed was Soviet strength and U.S.
weakness.
- The Star Wars initiative was certainly controversial and garnered a great deal of
opposition, not least in the scientific community in which opposition was led by Carl
Sagan (1934–1996) and the Nobel Laureate, Hans Bethe (1906–2005).
- The opposition saw the Star Wars initiative as politically destabilising because it
implied a winnable nuclear war. In fact, over 6500 scientists and engineers signed a
petition pledging not to work on the Strategic Defense Initiative.
Fall of the Berlin Wall
- When the Berlin Wall began to crumble in 1989, an early indicator of the end of the
Soviet Union, it became clear that the concerns about Soviet strength were
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unfounded.
The Marshall Institute needed a new enemy. The new enemy identified by Jastrow,
Nierenberg and Seitz was what they called “environmental extremism”.
But why? They viewed environmentalism to be socialism. This seems a bit of a
stretch, so what was their thinking. Oreskes and Conway argue that the reason this
association was made was because the issues of concern to environmentalists at the
time, including acid rain, the ozone hole, the pesticide DDT, and indeed climate
change, required government intervention.
Infamous tobacco industry memo
- However, it wasn’t just environmental causes that galvanised the Marshall Institute's
opposition to regulation. Another concern that was receiving national attention was
that of “second-hand smoke”.
- In the 1950s, the tobacco industry had launched a strategy that refuted and ridiculed
the science that linked smoking to health issues, including lung cancer.
- In 1979, Seitz had been hired by the R. J. Reynolds Tobacco Company to head their
Medical Research Committee and had learnt many of the tricks of the trade,
especially around doubt-mongering.
- The use of doubt by the tobacco industry is perhaps best articulated in the infamous
Smoking and Health Proposal memorandum, which states, “Doubt is our product
since it is the best means of competing with the ‘body of fact’ that exists in the minds
of the general public.” (Smoking and Health Proposal, 1969).
- These doubt-mongering tactics would prove useful in Seitz's contrarian efforts to cast
doubt on the science of climate change.
"Junk science"
- Seitz and the Marshall Institute were joined in their battle against regulating secondhand smoke, by another scientist, Fred Singer.
- Singer was an environmental physicist, and had been the first Director of the U.S.
National Weather Satellite Service.
- Singer called the EPA’s study about cancer risks of second-hand smokers, “junk
science”.
- why an environmental physicist was writing reports criticising the work of the EPA on
second-hand smoke. “…if we do not carefully delineate the government’s role in
regulating…dangers there is essentially no limit to how much government can
ultimately control our lives.”
- This again confirms the assertion of Oreskes and Conway that the anti-environmental
contrarianism of Singer, Seitz, Nierenberg, and Jastrow, was driven by a political
agenda to thwart government regulation.
Promoting doubt on CFCs
- Seitz, Nierenberg, Jastrow, and Singer, applied the tobacco industry playbook to the
environmental issues of the time. They cast doubt on the science behind many of
these environmental issues.
- They argued that chlorofluorocarbons were not responsible for ozone loss in the
stratosphere.
Promoting doubt on acid rain
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They argued that the sulphur dioxide being released by coal-fired power plants was
not responsible for the acid rain that was destroying forests. Instead, they argued that
this was due to volcanic emissions.
Promoting doubt on climate change
- They argued that global warming was caused by natural variations in solar radiation;
that any warming caused by greenhouse emissions is swamped by natural climate
variations.
- They further claimed that there was no scientific consensus, and indeed that there
were benefits to increased carbon dioxide in the atmosphere through higher
agricultural productivity.
- Fred Singer was able to use his credentials as an environmental physicist to promote
the contrarian view about climate change and to argue that no consensus existed
with regard to human-induced climate change
- In the U.K. in 2007, promoters of the contrarian position were able to have a
polemical documentary film, entitled The Great Global Warming Swindle, released on
a national television network.
- The film's critics argued that it had misused and fabricated data, relied on out-of-date
research, employed misleading arguments, and misrepresented the position of the
IPCC.
Luntz memorandum
- The political and communications consultant, Frank Luntz, wrote a memo that in
2002 found its way to the President George W. Bush White House.
- The approach outlined in the leaked Luntz memo encapsulates the history and
continuing approach of those peddling the contrarian position both inside and outside
of politics. A significant fraction of the public accepts the deniers’ allegations as true,
or at least are confused by them, and therefore do not know what to think or whom to
trust. Science has been effectively undermined, which has eroded public support for
the decisive action needed to avoid the worst effects of global warming.
Concept quiz
Which U.S. President spoke of the need to take “concrete action to protect the planet”?
- George H. W. Bush
Which colourful phrase did John Sununu use to describe James Hansen's modelling
studies?
- "Technical poppycock"
Who wrote the book "Merchants of Doubt"?
- Naomi Oreskes, Erik Conway
Which institute was founded by Robert Jastrow, Frederick Seitz, and William Nierenberg?
- George C. Marshall Institute
Which phrase from the infamous tobacco industry memo informed the approach taken by
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climate change deniers to convince the public that climate change isn't happening?
- "Doubt is our product"
2. Discuss the relationship between neoliberal thinking and lack of regulation to
support mitigating climate change
On neo-liberalism
- Government intervention as the antithesis of the free market is the defining feature of
the political school of thought that is neoliberalism.
- Modern neoliberalism focusses on deregulation and releasing the magic of the free
market.
- In his book, Capitalism and Freedom, the Nobel Laureate, Milton Friedman (1912–
2006), discusses the role of economic capitalism in liberal society.
- Outlining his thesis concerning the dangers of government regulation to liberal
freedoms, Friedman wrote that, “Many people want the government to protect the
consumer. A much more urgent problem is to protect the consumer from the
government.” He further noted that, “Civic freedom and free markets are inextricably
linked: to control markets, states have to control people. Without free markets, we’re
on the slippery slope to tyranny…”.
- The downfall of the Soviet Union only strengthened the political consensus that
neoliberalism was correct.
- For the Marshall Institute, a return to the regulation required to combat environmental
concerns, like climate change, was an dislike to their neoliberal political ideology.
- For them, regulation was about a loss of freedom; if you give up your economic
freedom by allowing the government to regulate the market place, then it is only a
matter of time before you lose your other freedoms as well.
3. Apply the CRAAP test and the Baloney Detection Toolkit to articles written
about climate change
CRAAP Test
Climate change myths
1. “Climate's changed before”
This lack of candour (openess) is an example of a straw man. That is when a claimant
misrepresents a position that is more easily argued against.
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Currency: Richard Lindzen authored an article entitled “Resisting Climate Hysteria”.
In that article, Lindzen wrote, “Climate is always changing...
Well we are currently on the Sixth Assessment Report of the IPCC, and this article
was written before the Fifth Assessment Report. The article is certainly dated, but the
content isn’t inconsistent with current research
The article itself references, for the time, recent research articles in amongst other
journals, Science and Nature.
Relevance: The article is certainly relevant to a search about whether climate has
changed in the past.
Authority: Let’s look at the author, Richard Lindzen. Well, prior to his retirement in
2013, he was the Alfred P. Sloan Professor of Meteorology at the Massachusetts
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Institute of Technology. Absolutely no problem here. Indeed, he was a lead author of
Chapter 7 of the IPCC's Third Assessment Report. Lindzen certainly has the
credentials to be making comment on the subject of climate change.
Accuracy: Now this is where there is problem. Previous climates can be explained
by natural causes, while current climate change can only be explained by an excess
of CO₂ released by human fossil fuel burning. Records of past climates indicate that
change happened on time scales of thousands to millions of years. As we saw in the
last lecture, the global rise in temperature that has occurred over the past 170 years
is unprecedented and has our fingerprints all over it.
Purpose: Lindzen is widely known as a contrarian, but is a highly-respected
scientist. After retiring from MIT, Lindzen took a position at the Cato Institute, an
organisation founded by and largely funded by the Koch brothers who have actively
sought to limit climate change legislation. Interestingly, Lindzen also took a contrarian
view on the issue of second-hand smoke.
In terms of the CRAAP test, I would argue that it fails on the basis of Accuracy and to
a lesser extent Purpose and Currency
Single cause fallacy is when a phenomenon is falsely attributed to a single cause,
even though other causes are possible.
It assumes that because the climate has changed from natural causes before, it can
only be changing from natural causes now.
2. “It's the sun”
Preferably this theory should make predictions that can be tested. These statements are
arguing that correlation is causation—this is the false cause fallacy.
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“there has been a steady increase in the numbers of sunspots, at the time when the
Earth has been getting warmer. The data suggests solar activity is influencing the
global climate causing the world to get warmer.”
Currency: there are certainly issues. This is a report from 2004 after all. I would want
more recent articles that would be more likely to reflect the current state of
understanding.
Relevance: No problem here. The article discusses the mechanisms by which the
Sun influences the Earth’s climate.
Authority: BBC News is widely-respected and is the world's largest broadcast news
organisation. The BBC is required by its charter to be free from both political and
commercial influence. How about David Whitehouse? Whitehouse has a Ph.D. in
astrophysics. One would imagine that with this background he was well placed to
report on science issues, including climate change. The report was on the work of
scientists at the Institute for Astronomy in Zurich, and appears to be accurately
represented.
Accuracy: Here is where we have problems. What does the science say? Well in the
last 35 years of global warming, the Sun has shown a slight cooling trend. Sun and
climate have been going in opposite directions. In the past century, the Sun can
explain some of the increase in global temperatures, but a relatively small amount.
Purpose: Here it’s not too easy to ascertain. This was an interesting scientific study
being reported in a respected news service. With hindsight though, we might
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question whether the author, Whitehouse, had a contrarian motive. The article was
over 500 words long and didn’t mention the possibility of human-influence on climate
change until the penultimate paragraph. Whitehouse himself left the BBC in 2006 and
has since written articles that have consistently taken a contrarian view of climate
change. He currently holds a position on the Academic Advisory Council of the
contrarian Global Warming Policy Foundation.
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On balance, this article fails the CRAAP test on Currency, Accuracy and Purpose.
Fallacy of incomplete data
In trying to blame the Sun for climate change, they cherry pick the data.
They only show data from periods when solar and climate data track together. For
example, temperature and solar activity correlate pretty well between 1880–1980.
This limited period would be the focus for their argument. They draw a false
conclusion by ignoring the last few decades when the data shows the opposite result.
3. “The Earth’s cooling”
- The third climate change myth we can look at is the claim that is sometimes proffered
that global warming is no longer happening and that, in fact, the Earth is cooling.
- Currency: it can certainly be argued that the article is a little dated. However, similar
claims can be found in more recent articles so let’s continue.
- Relevance: if we were looking for articles about climate change and whether climate
change is happening, then there is no problem here. Of course, I would still be
looking for further articles, but this is certainly relevant.
- Authority: The article states that Svensmark approved the translation. So, let’s look
at Svensmark’s qualifications. Well, Svensmark is a physicist at the Centre for SunClimate research with the Danish National Space Institute at the Technical University
of Denmark. He has been working and publishing his research in the area of climate
change throughout his career. Svensmark’s credentials are entirely appropriate.
- Accuracy: Once more this is where the problem lies. All indicators show that
warming is still happening. When looking for evidence of global warming, there are
many different indicators that we should look for. Whilst it's natural to start with air
temperatures, a more thorough examination should be as inclusive as possible; snow
cover, ice melt, air temperatures over land and sea, even the sea temperatures
themselves.
- Purpose: Certainly, the website on which the translation has been posted is a known
purveyor of climate change denial, but Svensmark seems to be following his
research. Svensmark argues that while the role of greenhouse gases in climate
change is considerable, solar variations play a larger role.
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The article fails the CRAAP test on Currency and Accuracy.
Cherry picking data
One of the most common misunderstandings amongst climate deniers is the
difference between short term noise and long-term signal.
For climate change, it is the longterm trends that are important; measured over
decades or more, and those long-term trends show that the globe is still,
unfortunately, warming.
4. “Animals and plants can adapt”
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Currency: the article is too old and we should move on and look for something more
recent
Relevance: The article does not expand on this single statement, beyond stating that
this conclusion is drawn from research published in journals such as Science and
Nature. This article does not help me identify whether animals and plants can adapt
to climate change.
Authority: The Hudson Institute does not discuss climate change specifically in its
areas of interest. No fellows on staff are expert in climate science.
Accuracy: The science says that human-caused climate change is occurring too
rapidly for species to be able to adapt. Plants and animals are currently dying off at a
rate that is 100 to 1000 times faster than the average rate of extinction over
geological timescales. Because of this, there is mounting evidence that we are
heading towards a mass extinction event.
Purpose: The article appears to be a puff piece promoting the book “Unstoppable
Global Warming Every 1,500 Years” by Fred Singer and Dennis Avery. Even more
concerning is that Avery was a Senior Fellow at the Hudson Institute.
This article fails the CRAAP test by every measure.
5. “It's not us”
- First, they concur with the believers that the Earth has been warming since the end of
a Little Ice Age around 1850. The cause of this warming is the question. Believers
think the warming is man-made, while the skeptics believe the warming is natural and
contributions from man are minimal and certainly not potentially catastrophic à la Al
Gore
- Currency: we are faced with the issue that the article is a little dated, but it reveals
similar claims to those one could read in articles that have been written more
recently.
- Relevance: the article discusses climate change in light of the hacking of emails
from the University of East Anglia's Climate Research Unit62, the so-called
Climategate. This controversy has been thoroughly debunked, but at the time of the
article the debate was still raging. The relevance of the article rests on what I am
researching. If it was whether climate change is human caused, then the article lacks
depth. But if I was concerned about what scientists had said in the hacked emails,
then this article would certainly be relevant.
- Authority: The article is written by Neil Frank who has a Ph.D. in meteorology from
Florida State University and was the Director of the U.S. National Hurricane
Center65, so the author certainly has the authority to pass comment.
- Accuracy: the science says that global warming is human caused, because it has
our “fingerprints” all over it. Ultimately, proving that global warming is due to humans
is about establishing causation. This is never an easy thing, but with regard to
climate change there are number of lines of evidence that together are convincing
that global warming can be attributed to human-induced emissions of greenhouse
gases.
- Purpose: The polemical style of the article is revealing. It calls the climate scientists
that are identifying the dangers of climate change as being “alarmists”. It argues that
the emails reveal a conspiracy between U.S. and U.K. climate scientists to adjust the
data to make it look as if global warming is real. This language is a red flag.
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The article fails the CRAAP test on Currency, Accuracy and Purpose.
This article comes across as more of ad hominem attack on the climate scientists
rather than as a reasoned argument that global warming is natural.
Concept quiz
Why is Richard Lindzen considered to be an authority to speak on the topic of climate
change?
- He's a climate scientist
Which of the following is an example of a single cause fallacy?
- An engineer stated that previous engine failures had been caused by the control
electronics overheating and so argued that the current engine failure is also due to
problems with the control electronics.
With hindsight, what raised concerns as to the purpose of the article entitled "Sunspots
Reaching 1000-year High"?
- Not mentioning the possibility of human-induced climate change until the penultimate
paragraph
- The author's subsequent portfolio of articles on climate change always taking a
contrarian position
- On leaving the BBC, the author took up a position with the contrarian Global
Warming Policy Foundation
Which of the following is an example of a fallacy of incomplete data?
- Frederick argued that smoking isn't bad for your health as his grandfather smoked
and was running marathons at the age of 80.
For which topics of essays would the article entitled “While The Sun Sleeps” be relevant?
- Whether climate change is happening
- Whether the sun is responsible for climate change
Which of the following is a key indicator of global warming
- Species migrating poleward
Compared to average extinction rates over geological timescales, what rate is the current
extinction rate of plants and animals?
- 100–1000 times faster
For an article on climate change, why might it be considered current?
- It's been written since the IPCC Fifth Assessment Report
- The science hasn't changed since it was written
Which of the following is an example of an ad hominem fallacy?
- This fallacy occurs when, instead of addressing someone's argument or position, you
irrelevantly attack the person or some aspect of the person who is making the
argument.
- A teacher argued that Freund's ideas are not worth studying, because he used
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cocaine.
Which of the following is an indicator of human fingerprints on climate change?
- Less oxygen in the air
4. Describe both the key indicators of global warming and the human fingerprints
of climate change
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All of these indicators of global warming were predicted. Climate scientists do not rely
on any one indicator in order to claim that global warming is happening, they rely on
the preponderance of evidence from many different indicators
10 Indicators of human fingerprint on climate change
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Circled in red: There are four pieces of evidence that humans are raising CO₂ levels.
Circled in white: two observations that show that CO₂ is absorbing more infra-red
radiation.
Circled in yellow: four observations that show that the observed pattern of warming is
consistent with what is predicted to occur during global warming.
The stratosphere should cool because of the infra -red radiation being trapped in the
troposphere.
The tropopause, which separates them, will rise.
Ionosphere would shrink
The attribution of climate change to human activity is not based solely on computer
modelling.
The series of empirical measurements we have just discussed point to the conclusion
that humans are causing the planet to warm.
5. Reflect on your susceptibility to cognitive bias so as to better combat climate
change denial.
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The fossil fuel industry, political lobbyists, media and individuals have spent some 30
years casting doubt on the reality of climate change.
The world’s five largest publicly-owned oil and gas companies alone spend about
US$200 million a year on lobbying to control, delay or block binding climate policy.
What forms of denial convince the public to delay action on climate change?
1. Science denial
- science of climate change is not settled. That there is no consensus. That climate
change is just part of the natural cycle.
2. Economic denial
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3.
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climate change is too expensive to fix
This is a form of self-fulfilling prophecy. ("predicting" or expecting something, and
subsequently the person's resulting behaviors align to fulfill the belief)
Economists estimate that we could fix climate change now by spending 1% of world
GDP.
However, if we delay to 2050, it could cost over 20% of world GDP.
This denial recognises the need for intergenerational equity.
Humanitarian denial
CO2 is good for us
Climate change is good for us.
That longer, warmer summers make farming more productive.
That plants need carbon dioxide and so more of it acts as a fertiliser.
That warmer winters will lead to fewer deaths. This denial is particularly pernicious as
it solely considers the effect on people living in temperate climates, and not those
living in tropical climates. Further, it’s not even true, but points to the need for
international equity.
4. Political denial
- Other countries are not taking actions
- This denial ignores the historic legacy of greenhouse gas emissions. It further
highlights the need to recognise the ethical responsibility of developed nations to
take action first.
5. Crisis denial
- We should not rush into committing to binding international agreements given the
uncertainty raised by the previous areas of denial.
Susceptibility to cognitive bias
- But why might we as individuals accept these forms of denial? The answer is our
susceptibility to cognitive bias. We are all susceptible to cognitive bias. Recognising
this is key to being able to think critically.
1. Time-discounting bias (tendency to discount the future)
- First, despite claiming that we want to leave the world in good condition for future
generations, people intuitively discount the future to a greater degree than can be
rationally defended.
- People too often use an extremely high discounting rate regarding the future—that is,
they tend to focus on or overweight short-term considerations.
- We are most likely to discount the future when the future is uncertain, distant, and
when intergenerational distribution of resources is involved.
- Specifically, when people espouse the view that the earth’s resources should be
preserved, they tend to think about their descendants.
- But when consumptive opportunities arise today that would inflict environmental
costs on future generations, they begin to view “descendants” as a vague group of
people living in a distant time.
- From a societal perspective, overweighting present concerns can be viewed as both
foolish and immoral, as it robs future generations of opportunities and resources.
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E.g. climate change is too expensive to fix - Time-discounting bias occurs in many
ways. Here it is happening because future costs are being discounted less than
present costs.
2. Illusory truth effect
- Lead us to conclude that energy problems do not exist or are not severe enough
- Positive illusions have benefits: they can enhance self esteem (?), increase
commitment to action, and encourage persistence at difficult tasks and strength in
the face of adversity.
- But they also have drawbacks: they can reduce the quality of decision-making and
prevent us from acting in time to address significant problems
- We all hold a wide variety of positive illusions, yet two are particularly relevant to
inattention of energy and climate change: unrealistic optimism and the illusion of
control.
- Unrealistic optimism leads us to believe and act as if the repercussions of climate
change will be far less severe than the scientific community predicts.
- The illusion of control leads us to believe that scientists will invent new technologies
to solve the problem. As a result, the unrealistic illusion that a new technology will
emerge serves as an ongoing excuse for the failure to act today.
3. Self-serving bias
- Tendency to expect others to do more than we do
- We justify our preference on the basis of fairness by changing the importance of the
attributes affecting what is fair.
- Egocentrism leads all parties involved to believe that it is honestly fair for them to
bear less responsibility for reversing climate change than an independent party would
judge as fair.
- The problem is worsened not by a desire to be unfair but by an inability to view
information objectively
- They interpret information in a way that increases their self-esteem
Evolution of the climate change denier
Self-serving bias
- scientists are wrong (science denial)
Illusory truth effect
- climate change does not exist (science denial)
- humans are not to blame (science/humanitarian denial)
Self-serving bias
- others are to blame (political denial)
Time-discounting bias
- too costly to fix (economic denial)
- current generation benefits at cost to future generation (crisis denial)
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From "There is no problem" --> "We aren't responsible" --> "It's too expensive to fix"
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Concept quiz
What form of denial is insisting that climate change is good because plants need carbon
dioxide?
- Humanitarian denial
Lecture 8 - On the Reliability of Projected Climate Change
1. Summarise how climate models prove their reliability through hindcasting and
successful forecasting
Discussed how climate scientists have developed the models so that we can have
confidence in their predictions of future climate states.
Computer programs
- Models are one of the ways in which scientists show understanding of a
phenomenon.
- The mathematical models that incorporate our best understanding of the Earth
system are expressed in the form of computer programs that are able to calculate
climate and change in climate. These computer programs are known as climate
models.
Projections, predictions and scenarios
- Projections are model-derived estimates of future climate.
- When a projection is branded “most likely” it becomes a prediction.
- The reason for this difference is that many of the climate simulations calculated are
for future scenarios that are seen as possible.
- A scenario is a coherent, internally consistent and plausible description of a possible
future state of the world.
- Scenarios have a demographic, socio-political, economic and technological storyline.
Why we should have confidence in these models?
Hindcasting - reproducing past models
- Reproducing past observations is known as hindcasting.
- Comparing model results with past measurements
- Models of past climate are known as initial-value models.
- They are given an initial state, say the atmosphere of 1850 or 1870, and are then
allowed to freely run forward in time.
- Once running, these climate models do not correct themselves using observations.
- Such a model should be able to reproduce random variations in the climate system.
- However, it will not be able to reproduce the observed changes in Earth surface
temperature.
- Although the model is free running, it does need to be forced by natural and
anthropogenic (human-caused) changes.
- Natural forcing involve incorporating solar variations and volcanic activity.
- Anthropogenic forcings involve the changes in greenhouse gases, sulphate aerosols,
and land-use.
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We have already seen the graphs of model calculations from the Sixth Assessment
Report.
The figure here shows that there is good agreement with the observed temperature
record and further makes the case that the increase in temperature can only be
explained by anthropogenic forcings, most importantly the increasing atmospheric
burden in greenhouse gases due to the burning of fossil fuels.
Supercomputers
- Installation of the three Cray XC40 supercomputers at the UK Met office in 2017
- Capable of 14 quadrillion calculations per second
- Despite using some of the most powerful supercomputers on the planet, these
climate models need to divide the planet up into grid cells to make the calculations
more manageable.
- This means that at every step of the model through time, it calculates the average
climate of each grid cell.
- However, there are many processes in the climate system and on the Earth’s surface
that occur on scales within a single cell.
- For example, the topography will be averaged across a whole grid cell in the model,
meaning it potentially overlooks the detail of any physical features such as mountains
and valleys.
- Similarly, clouds can form and dissipate at scales that are very much smaller than a
grid cell.
Parameterisation
- To solve this problem, these variables are “parameterised”, meaning their values are
defined in the computer code rather than being calculated by the model itself.
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This graphic shows some of the processes that are typically parameterised in
models.
May also be used as a simplification where a climate process isn't well understood.
Parameterisations are one of the main sources of uncertainty in climate models.
Each research group will approach the parameterisation of a climate process in a
slightly different way.
This means that the climate models in the IPCC reports give different answers even if
they are initialised with the same climate state.
The variance in the global average temperature from these different models gives us
a sense of the uncertainty in the model calculations.
This is why it is important not to rely on any one climate model, or to describe any
one model as being the “best”.
These hindcast calculations give a great deal of confidence that climate models
“understand” the climate processes that led to the increase in temperature since the
Industrial Revolution.
However, the future climate is expected to be still warmer.
It could be argued that this represents an extrapolation (action of estimating or
concluding something by assuming that existing trends will continue) beyond the
climate states in which we know, through hindcast comparisons, that climate models
perform well.
Paleoclimate modelling
- To resolve this dilemma, scientists have constructed paleoclimate models that have
attempted to reproduce the proxy temperature records for much earlier climates,
when temperatures were vastly outside the envelope witnessed since the Industrial
Revolution.
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This figure shows global average temperature variations through the last 400 million
years as predicted by the Hadley Centre Coupled Climate Model version 3, an early
version of the climate model used by the U.K. Met Office.
These numbers are compared with geologically derived estimates of temperature
variability over the same period.
Future projections of temperature change using different Representative
Concentration Pathways are shown in the right-hand most panel.
Concept quiz
In climate science, what is a prediction?
- A projection that is viewed "most likely"
Which of the following climate models most accurately reproduces past global surface
temperature?
- A climate model that includes both anthropogenic and natural forcings
Models of the past
- Perhaps the most notable climate change projections of the 1980s were those of
James Hansen.
- In 1988, Hansen and colleagues reported climate model simulations for three
different emission scenarios.
- Scenario A assumed continued exponential greenhouse gas growth.
- Scenario B assumed a reduced linear rate of growth.
- Scenario C assumed a rapid decline in greenhouse gas emissions around the year
2000.
- Scenario A was essentially a worst-case scenario, whereas Scenario C was the bestcase. Scenario B was the most-likely scenario.
- None of these future scenarios were an exact match to what happened of course,
and we now understand and simulate more of the complex drivers of change which
were not included in Hansen’s work.
Hansen's climate model projection
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This figure shows the projections for these three scenarios, together with the
observed temperature change.
Essentially the data from 1958 to 1984 represent a hindcast, and that after 1984
represent a forecast.
The easiest assessment of the quality of these projections is to compare the
temperature trends predicted against that observed.
Given that the actual greenhouse gas emissions have been closest to Scenario B,
let’s compare against Scenario B.
Scenario B has a 0.26°C per decade temperature trend, whereas the observed
GISTEMP temperature trend has been 0.19°C. This is close, but Scenario B has
clearly overestimated the observed temperature trend in the forecast period.
Well, there are two main reasons for Hansen’s overestimate.
First, Scenario B, which was closest to reality, slightly overestimated how much
atmospheric greenhouse gases would increase.
And second, Hansen’s model had a rather high climate sensitivity of about 4.2°C for
a doubling of atmospheric CO2.
To have accurately reproduced the global warming observed, Hansen’s climate
model would have needed a climate sensitivity of about 3.4°C. This is within the likely
range of climate sensitivity values listed as 2.5–4°C by the IPCC for a doubling of
CO2.
This would be just a little bit higher than the most likely value currently widely
accepted as 3°C.
The appropriate conclusion to draw from these results is not that the projections were
wrong.
The correct conclusion is that Hansen’s study is another piece of evidence
that climate sensitivity is in the IPCC stated range of 2.5–4°C for a doubling
of CO2.
Spatial distribution of temperature anomaly
- Hansen’s study also produced a map of the projected spatial distribution of the global
surface temperature change in Scenario B for the 2010s.
- We can compare this map with observed global temperature maps to evaluate the
accuracy of Hansen’s spatial distribution.
- This map from NASA’s Goddard Institute for Space Studies shows the global surface
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temperature anomaly in the period 2010–2019 with respect to the 1951–1980
baseline.
Although the actual amount of warming has been less than projected in Scenario B,
this is due to the fact that Hansen's climate model projected a higher rate of warming
due to a high climate sensitivity.
However, as you can see, Hansen's model correctly projected amplified warming in
the Arctic, as well as hot spots in northern and southern Africa, west Antarctica, and
more pronounced warming over the land masses of the northern hemisphere, among
other things.
The spatial distribution of the warming is very close to his projections.
Hansen’s work was stunningly accurate quite frankly. Modern climate models have a
grid resolution of a degree or less.
Hansen’s model had a far coarser grid. His model grid was 8° × 10°.
Given the effect that grids have on the need to parameterise climate processes, we
can understand the source of Hansen’s model’s high climate sensitivity.
People
- Although Svante Arrhenius was the first to estimate the increase in surface
temperature due to a doubling of CO₂, Manabe was the first to perform a
computational experiment in which CO₂ was doubled.
- Further, Manabe was one of the first people to use a realistic distribution of land
masses and a mixed-layer model of the very upper ocean in his modelling.
- He was also one of the first scientists to show that how clouds were parameterised
had a large effect on a model’s climate sensitivity.
Concept quiz
Which emission scenario in the Hansen et al. (1988) study most closely followed the
observed temperature warming?
- Scenario B
What were the two main reasons why Hansen's most likely scenario overestimated the
observed temperature trend?
- The model climate sensitivity was too high
- The model scenario overestimated how much greenhouse gases would increase
2. Predict the effect of feedback loops and discuss the impact of feedback on
model projection uncertainty
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These couplings directly describe cause and effect relationships, and the feedback
loops describe forms of causal mechanisms.
Positive feedback
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Occurs in a feedback loop that exacerbates a small disturbance
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It leads to instability
One of the features of positive feedback is that it tends to lead to instability via
exponential growth.
A positive coupling is where an increase in one element leads to an increase in the
connected element.
Or a decrease in an element leads to a decrease in the connected element.
The changes in the elements are in the same direction for positive couplings, but are
in opposite directions for negative couplings.
Negative feedback
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Occurs when the output of a system is fed back in a manner that reduces the
fluctuation in the output
It leads to stability
For example, an increase in blood glucose levels will lead to an increase in insulin
secreted by the pancreas, that in turn will lead to a decrease in the blood glucose
level
The result is a stable blood glucose level
Negative feedback in the Earth system
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Coupling between photosynthetic rate in plants and atmospheric CO2 concentrations
Note that in the feedback loop between the photosynthetic rate and atmospheric CO2
there is a negative coupling (denoted by a circle-headed arrow) and a positive
coupling (denoted by a normal arrow).
The negative coupling describes the effect where an increase in one element leads
to a decrease in a connected element.
Or vice versa, where a decrease in one element leads to an increase in the
connected element.
Top: increase photosynthesis → lower CO2 (opposite direction, hence neg
coupling)
Bottom: lower CO2 → lower photosynthesis (same direction, hence pos
coupling)
Positive feedback in the Earth system
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An example of a positive feedback loop might be seen in the coupling between the
mass of an ice sheet and the elevation of the ice sheet.
If the ice sheet melts, then the ice sheet will move to a lower elevation where it is
warmer.
The ice sheet experiencing warmer temperatures will melt faster completing a
positive feedback loop.
This feedback loop will not stabilise. The loop will continue until the entire ice sheet
has melted.
Surface temperature and water
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In this first feedback loop, a positive feedback loop, an increase in surface
temperature leads to greater evaporation.
Greater evaporation leads to more water vapour in the atmosphere.
Remembering that water vapour is a greenhouse gas, the increase in water vapour
leads to an enhanced greenhouse effect. The enhanced greenhouse effect leads to
greater surface temperature.
All of the couplings are positive.
The second feedback loop is a negative feedback loop.
The increase in surface temperature again leads to greater evaporation.
But this time, the greater evaporation leads to increased cloud cover.
Clouds are reflective. An increase in cloud cover leads to an increase in albedo.
However, the increased albedo leads to a decrease in surface temperature,
completing a negative feedback loop.
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Note that this loop includes a single negative coupling.
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In general, any feedback loop that includes an odd number of negative couplings
will be a negative feedback loop.
Whereas, a feedback loop that includes zero or an even number of negative
couplings will be a positive feedback loop.
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Doubling CO2
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What would be the global average temperature in an atmosphere with double the
pre-industrial CO2 concentrations?
If CO2 concentrations were doubled instantaneously, the outgoing radiation at the top
of the atmosphere would be reduced by approximately 3.7 watts per metre squared,
because the increased CO2 concentrations would absorb more terrestrial infra-red
radiation.
There would, therefore, be an imbalance between the amount of radiation entering
the Earth system and the amount leaving the Earth system.
This imbalance is known as the radiative forcing.
With more energy entering the Earth system than leaving, the Earth system will warm
up until balance is restored.
Restoring balance
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If we double CO2, the transmittance of terrestrial infra-red radiation through the
atmosphere is decreased, and less total radiation will leave the atmosphere.
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In order to bring the system back into balance, the temperature of the Earth surface
has to increase.
Assuming nothing else changes, a doubling of CO2 will lead to an increase of
surface temperature of about 1.25°C.
However, as we noted in the feedback loops this increase in surface temperature will
change other things. A major effect of increased surface temperature is greater
evaporation and hence more water vapour in the atmosphere.
Water vapour is a powerful greenhouse gas (the most important in fact) and so the
surface temperature will increase further.
The positive feedback loop will increase the initial temperature rise by a further 60%.
Other feedback loops include the melting of ice allowing the surface underneath to
absorb some sunlight instead of being reflected back to space.
Melting ice and exposing the underlying surface decreases the albedo.
This positive feedback loop increases the initial temperature rise by a further 20%.
If the water vapour nucleates to form clouds then it is possible for there to be a
negative feedback loop.
However, the effect of clouds is uncertain and depends on the altitude at which the
clouds form.
Climate sensitivity
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The net effect of the initial warming due to doubling CO2 and the feedbacks in the
Earth system is known as the climate sensitivity.
The best estimate of climate sensitivity in the Sixth Assessment Report is 3°C with a
likely range of between 2.5°C and 4°C.
This figure shows how this range in climate sensitivity has changed over the years
from the First Assessment Report until the current assessment report. Over these
reports, the range of climate sensitivity has decreased as the models have improved.
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Reaching equilibrium
- Note that the increase in temperature due to climate sensitivity is the expected
increase when the Earth system reaches equilibrium.
- It doesn’t happen overnight. Most of the imbalance in energy entering and leaving the
Earth system, as CO2 concentrations are increased, goes into heating up the
oceans.
- Oceans take a long time to heat up and so there is a significant lag between reaching
the expected equilibrium surface temperature and the current surface temperature.
-
For example, the current increase in Earth surface temperature since the 1850–1900
baseline is about 1.1°C.
However, the current levels of CO2 in the atmosphere would imply an equilibrium
Earth surface temperature of over 1.7°C.
Avoiding such an equilibrium temperature requires us to not only stop adding to the
atmospheric CO2 concentration, but to reduce it.
Many of the feedback loops that add to climate sensitivity involve processes that
need to be parameterised.
This is the reason why getting parameterisation right is so important, and why it can
add significantly to the uncertainty in estimates of future climate change.
Concept quiz
If a climate model has a climate sensitivity of 3.5℃ and the initial warming in the model due
to a doubling of CO₂ is 1.5℃, what is the effects of feedback in the model?
- Feedbacks increase the initial warming by 2.0℃
In the feedback loop involving the photosynthetic rate of plants and the concentration of
atmospheric carbon dioxide, how does the concentration of atmospheric carbon dioxide
react to an increase in photosynthetic rate of plants?
- CO₂ concentrations decrease
3. Describe and contrast the climate change projections resulting from possible
future climate scenarios
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We have just seen that Hansen and colleagues developed emissions scenarios to
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describe possible futures.
This enabled Hansen to explore future climate change and to argue why mitigation is
important.
Since then this approach to exploring future climate change has become far more
sophisticated.
Special report on emissions scenarios
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In the 1990s, the IPCC published the Special Report on Emissions Scenarios.
These scenarios were constructed to explore future developments in the global
environment.
They had storylines, four in total, that highlighted the main scenario characteristics
and dynamics, and the relationships between key driving forces.
The four storylines combine two sets of divergent tendencies: one set varying
between strong economic values and strong environmental values, the other set
between increasing globalisation and increasing regionalisation.
Representative concentration pathways
- A Representative Concentration Pathway (RCP) is a greenhouse gas concentration
trajectory
- Each RCP is labelled with their radiative forcings
- RCP1.9 is a pathway that limits global warming to below 1.5°C, the aspirational goal
of the Paris Agreement
- RCP2.6 is a “very stringent” pathway that requires CO2 emissions to start declining
by 2020 and go to zero by 2100
- RCP4.5 is an “intermediate” scenario that requires emissions to peak around 2040,
then decline
- RCP7.0 is a baseline outcome rather than a mitigation target—a baseline outcome is
one that might occur in the absence of any concerted international effort to address
climate change
- RCP8.5 is a very high emissions scenario that is thought unlikely to occur, but might
be possible because feedbacks are not well understood
- The most recent attempt to narrate future climate change is the development of a
Scenario Matrix Architecture. This scenario framework was used in the recent Sixth
Assessment Report of the IPCC.
- The construction of this framework was two pronged.
- First, a set of Representative Concentration Pathways (or RCPs) were developed
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that described different levels of greenhouse gases and other radiative forcings that
might occur in the future.
These pathways were developed to span a broad range of radiative forcing in 2100.
The radiative forcings ranged from 1.9 to 8.5 watts per metre squared.
Shared Socioeconomic Pathways (SSP)
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Second, a set of Shared Socioeconomic Pathways (or SSPs) were developed that
described how socioeconomic factors may change over the century.
These factors include population, economic growth, education, urbanisation, and the
rate of technological development.
In total five different pathways have been developed that describe how the world
might evolve in the absence of climate policy.
The scenario matrix is formed when the different climate change mitigation targets
described in the Representative Concentration Pathways are combined with the
Shared Socioeconomic Pathways.
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The first narrative, SSP1, describes a world of sustainability-focused growth and
equality.
- Titled “Sustainability—Taking the Green Road”, SSP1 narrates a future in
which the world shifts gradually toward a more sustainable path,
emphasizing more inclusive development that respects perceived
environmental boundaries.
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The second narrative, SSP2, describes a world where trends broadly follow their
historical patterns.
- Titled “Middle of the Road”, SSP2 narrates a future in which the world follows
a path in which social, economic, and technological trends do not shift
markedly from historical patterns.
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The third narrative, SSP3, describes a fragmented world of resurgent nationalism.
- Titled “Regional Rivalry—A Rocky Road”, SSP3 narrates a future in which
the world descends into resurgent nationalism, where concerns about
competitiveness and security, and regional conflicts push countries to
increasingly focus on domestic issues.
- Greatest socio-economic challenges for both mitigation and adaptation
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The fourth narrative, SSP4, describes a world of ever-increasing inequality.
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Titled “Inequality—A Road Divided”, SSP4 narrates a future in which highly
unequal investments in human capital, combined with increasing disparities in
economic opportunity and political power, lead to increasing inequalities and
stratification both across and within countries.
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The fifth narrative, SSP5, describes a world of rapid and unconstrained growth in
economic output and energy use.
- Titled “Fossil-fueled Development—Taking the Highway”, SSP5 narrates a
future in which the world places increasing faith in competitive markets,
innovation and participatory societies to produce rapid technological progress
and development of human capital as the path to sustainable development.
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These narratives describe alternative pathways for future society.
They present baselines of how things would look in the absence of climate policy,
and allow researchers to examine barriers and opportunities for climate mitigation
and adaptation in each possible future world when combined with mitigation targets.
From population growth to inequality
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In these figures, we can see how these narratives are expressed in terms of their
assumptions on global population growth, access to education, urbanisation,
economic growth, and levels of inequality.
SSP1 and SSP5 envision relatively optimistic trends for human development, with
substantial investments in education and health, rapid economic growth, and wellfunctioning institutions. (high mitigation, low adaptation)
They differ in that SSP5 assumes this will be driven by an energy-intensive, fossil
fuel-based economy, while in SSP1 there is an increasing shift toward sustainable
practices.
SSP3 and SSP4 are more pessimistic (both greatest challenges to adaptation) in
their future economic and social development, with little investment in education or
health in poorer countries, coupled with a fast-growing population and increasing
inequalities.
SSP2 represents a “middle of the road” scenario in which historical patterns of
development are continued throughout the 21st century.
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Further carbon dioxide concentration
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This figure shows how CO2 concentrations will evolve under different SSPs in order
to meet certain mitigation targets described by the RCPs.
The RCP1.9 and RCP2.6 pathways require very stringent mitigation efforts and will
require negative net carbon emissions to kick in around the middle of the century in
order to reduce CO2 concentrations.
These two pathways are shown here achieved using the SSP1 narrative. (Note that
the RCP1.9 pathway is the only pathway that supports a mitigation target in which
warming is limited to below 1.5°C.)
The less stringent RCP4.5, RCP7.0 and RCP8.5 pathways have been achieved
under the SSP2, SSP3 and SSP5 narratives respectively.
Can all mitigation challenges be met?
- Can all Representative Concentration Pathways be achieved under all Shared
Socioeconomic Pathways?
- The answer is no.
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This figure shows a combination of SSP and RCP model runs, with RCPs listed in
order of increasing mitigation and SSPs in the rough order of increasing mitigation
difficulty.
The ratios in each cell indicate the number of models that succeeded in making the
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scenario “work” out of the total number of models used.
Note that the models have significant difficulty in achieving RCP1.9 and RCP2.6
targets in either an SSP3 world or SSP5 world.
The RCP1.9 mitigation target can only be achieved by all models used under an
SSP1 narrative.
These scenarios give us the necessary information to force climate models and to
help us determine what future worlds will look like, what the effect on climate will be
in these possible future narratives.
Concept quiz
A climate scientist creates a new Representative Concentration Pathway, RCP6.0. What is
the radiative forcing of this new RCP?
- 6.0 W m⁻²
Which shared socioeconomic pathway represents a world that broadly follows historical
patterns?
- SSP2
Projection of climate change
Hot extremes
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This figure shows the assessment of observed change in hot extremes and the
confidence in human contribution to the observed changes in the world’s regions.
This assessment is mainly based on changes in metrics based on daily maximum
temperatures.
The hexagons represent different world regions. The colours represent the outcome
of the assessment.
The red colour indicates that there is at least medium confidence.
The confidence level for human influence on these observed changes is based on
assessing trend detection and attribution, and is indicated by the number of dots:
Three dots represents high confidence; two dots represents medium confidence;
and, one dot represents low confidence.
Note that in the SEA region for South East Asia, there has been an increase in hot
extremes and there is high confidence that this increase is due to human influence.
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Heavy precipitation events
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This figure shows the assessment of observed change in heavy precipitation and
confidence in human contribution.
This assessment is based on changes in indices of one-day or five-day precipitation
amounts.
Note again that in South East Asia, there has been an increase in heavy precipitation
although with low confidence that it is due to human influence.
Drought
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This figure shows the assessment of observed change in agricultural and ecological
drought.
This assessment is based on the observed and simulated changes in total column
soil moisture.
Currently there is low agreement in the type of change that is happening in South
East Asia.
Confidence and likelihood
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This level of confidence is based on a combination of the level of agreement and the
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quality of evidence.
A low degree of confidence translates to a 20% chance of being correct, a medium
degree of confidence to a 50% chance, and a high degree of confidence to an 80%
chance of being correct.
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When we look at projections, the IPCC will describe the likelihood of the results
discussed using this scale.
A “likely” occurrence has a 66% chance of happening, for example, and a “very
likely” occurrence has a 90% chance of happening.
Projected greenhouse gas emissions
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Back to the projections then, what are they?
The IPCC in their Sixth Assessment Report focused on five illustrative scenarios:
SSP5-8.5, SSP3-7.0, SSP2-4.5, SSP1-2.6, and SSP1-1.9.
The simulations begin to be forced by these scenarios in 2015. The scenarios with
high and very high greenhouse gas emissions, that is SSP3-7.0 and SSP5-8.5, have
CO2 emissions that roughly double from current levels by 2100 and 2050
respectively.
The scenario with intermediate greenhouse gas emissions, SSP2-4.5, has emissions
that stay around current levels until the middle of the century.
The scenarios with very low and low greenhouse gas emissions, SSP1-1.9 and
SSP1-2.6, have emissions that decline to net zero around or after 2050, followed by
varying levels of net negative CO2 emissions.
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Projections of global average temperature
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This figure shows the temperature change relative to an 1850–1900 baseline. The
very likely ranges are shown for the SSP1-2.6 and SSP3-7.0 scenarios.
Compared to 1850–1900, global surface temperature averaged over 2081–2100 is
very likely to be higher by 1.0°C to 1.8°C under the very low greenhouse gas
emissions scenario, that is SSP1-1.9, by 2.1°C to 3.5°C in the intermediate scenario,
that is SSP2-4.5, and by 3.3°C to 5.7°C under the very high greenhouse gas
emissions scenario, that is SSP5-8.5.
The last time global surface temperature was sustained at or above 2.5°C higher
than 1850–1900 was over 3 million years ago. The simulations indicate that global
surface temperature will continue to increase until at least the mid-century under all
emissions scenarios considered.
Global warming of 1.5°C and 2°C will be exceeded during the 21st century unless
deep reductions in CO2 and other greenhouse gas emissions occur in the coming
decades.
Simulations of global surface temperature
- While Earth's average global temperature is rising, the amount of warming is not
equal in all areas of the world.
- This visualisation shows how temperature changes will be distributed across the
globe for four out of the five scenarios discussed.
- The simulations shown here are from the Irish Centre for High-End Computing.
- Note that the baseline period is different.
- The baseline here is 1981–2010. As the simulations progress you can see that the
oceans warm more slowly than land because it takes much more heat to warm water
than land.
- In general, the middle of continents are expected to warm more than coastal areas.
- Regional topography such as mountain range will influence this too.
- At high latitudes, especially in and near the Arctic, temperatures are warming faster
than places closer to the equator. The Arctic is heating up about twice as quickly as
the global average.
- Singapore is projected to see between 1°C to 2°C increase in temperature for the low
greenhouse gas emissions scenario, to between 4°C to 5°C increase in temperature
for the very high greenhouse gas emissions scenario.
Simulations of global precipitation
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This second visualisation shows annual precipitation change from simulations by the
same group as before.
Although global average precipitation increases by between 3% to about 10%, this
additional precipitation is not distributed evenly around the globe.
Much of the increase in precipitation is expected to occur at high latitudes.
Increased snowfall near both poles may offset some of the melting of glaciers and ice
sheets in these regions by adding fresh ice to the tops of these features.
Some places in Antarctica are even gaining more snow via increased precipitation
than they are losing to melting caused by rising temperatures.
Some of the increased rainfall is expected to come in the form of more frequent
heavy downpours.
Some regions may receive a net increase in rainfall, but the increase may manifest
itself as heavier rains punctuated by longer dry spells between these deluges.
This change in precipitation patterns is likely to cause a greater incidence of flooding,
especially in combination with land use changes such as deforestation.
However, many regions near the equator and at mid-latitudes are expected to see
decreases in precipitation.
Many areas, especially in low- and mid-latitude regions, are expected to suffer from
more frequent and more severe droughts.
Dry conditions, warmer temperatures that produce longer "fire seasons", and
changes in ecosystems are expected to generate more and larger wildfires in some
areas.
Some presently dry regions may be glad to see increased rainfall, just as drier
conditions may benefit some currently very wet places.
However, heavy rainfall that causes flooding as well as extended or more frequent
droughts are likely to be disruptive to ecosystems and agriculture in the afflicted
regions.
Projections of Arctic sea ice
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The trends of the last few decades are expected to continue.
The Arctic is projected to be practically ice-free near mid-century under intermediate
and high greenhouse gas emissions scenarios.
Projections of ocean surface pH
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This figure shows the projected changes in global ocean surface pH.
The acidification due to the absorption of carbon dioxide from the atmosphere is
expected to continue. (Note that decreasing pH indicates acidification.)
Since the Industrial Revolution, the pH has dropped by 0.1 units.
This might not sound like much, but the pH scale is logarithmic, so this change
represents approximately a 30% increase in acidity.
The low greenhouse gas emissions scenarios do project a recovery of pH before the
end of the century, but the intermediate and high greenhouse gas emissions
scenarios all project continued decline.
This will further impact many ocean species like oysters and corals that make hard
shells and skeletons by combining calcium and carbonate from seawater.
If the pH gets too low, shells and skeletons can even begin to dissolve.
Projections of sea level
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This figure shows global average sea level change relative to 1900. It is virtually
certain that sea level will continue to rise over the 21st century.
By the end of the century, it is likely that sea level will rise by between 0.48–0.78
metres under the low greenhouse gas emissions scenario, and by between 0.79–
1.17 metres under the very high greenhouse gas emissions scenario.
Global average sea level rise above the likely range, approaching 2 metres in the
very high emissions scenario, cannot be ruled out due to the deep uncertainty in ice
sheet processes.
In the longer term, sea level is committed to rise for centuries to millennia due to
continuing deep ocean warming and ice sheet melt, and will remain elevated for
thousands of years.
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This figure shows the projected rise in sea level by 2300 in the low and very high
greenhouse gas emissions scenarios. Sea level rise greater than 15 metres cannot
be ruled out in the very high emissions scenario.
Qualitatively the trends seen in the climate changes to date are set to continue.
There is a great deal of variability in how climate change will evolve in the next
century that is highly dependent on which of the scenarios we end up following.
In the Singapore’s Climate Action Plan: Take Action Today, For a Carbon-Efficient
Singapore report published by the National Climate Change Secretariat, a number of
changes to Singapore's climate are noted.
Annual mean temperature has risen from 26.6°C in 1972 to 28.4°C in 2019 (the joint
warmest year on record together with 2016).
However, a large fraction of this temperature rise is associated with the urban heat
island effect.
This effect quantifies the difference in temperature between urban and rural areas.
In Singapore, incoming solar radiation heats up roads and bridges and this is
compounded by heat being actively emitted by vehicles, power plants, industry, and
even air conditioners. Singapore has seen bouts of very intense thunderstorms that
have led to flash floods, as well as dry spells.
In early 2014, Singapore experienced its longest dry spell since records began in
1869.
Concept quiz
Which region of the globe is warming fastest?
- Arctic
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If the IPCC states that something is extremely likely, what is the probability of it occurring?
- Greater than 95%
If ocean surface pH drops from 8.0 to 7.9, by how much does the acidity of the ocean
surface change?
- Increases by 30%
4. Explain how climate change mitigation strategies relate to principles of equity
So, what frameworks should govern the public policy towards climate change on the
international arena?
Universal declaration of human rights
- Given that our main concern is the impact of global warming on human communities,
perhaps a good place to start is the Universal Declaration of Human Rights.
- This Declaration was proclaimed by the United Nations General Assembly in Paris on
10 December 1948.
- In the Preamble to the Declaration, it is written that “recognition of the inherent dignity
and of the equal and inalienable rights of all members of the human family is the
foundation of freedom, justice and peace in the world…”.
- The reference to “all members of the human family” has both spatial and temporal
dimensions, which brings peoples of all countries and of all generations within its
scope.
- The reference to “equal and inalienable rights” affirms the basic equality of all
peoples across all generations in the human family.
- This argues strongly that action must be taken, but what principles should govern
action?
Principles to govern international action
- There are three principles that are frequently put forward as those that should govern
international action.
- The first principle is the Precautionary Principle that states that a lack of scientific
certainty should not prevent appropriate action being taken.
- This principle was acknowledged in Article 3.3 of the United Nations Framework
Convention on Climate Change.
- It was included because even in 1992, the threats of climate change were seen as
dangerous and potentially catastrophic.
- It was meant to spur international action, that a lack of full scientific certainty should
not be used as a reason for postponing cost-effective measures to prevent
environmental degradation.
- The second principle is that polluters should pay for the damage of their pollution.
- This is a well-known principle that has been written into environmental legislation for
a long time. (polluter pay principle)
- It recognises that carbon dioxide and many other greenhouse gases are global
pollutants, they affect the global commons.
- And the third principle is that of equity—both intergenerational and international
equity. (principle of equity)
- This principle is recognised, as just discussed, in the Universal Declaration of Human
Rights.
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Intergenerational equity argues that we hold the natural environment of our planet in
common with all members of our species: past generations, the present generation,
and future generations.
As members of the present generation, we hold the Earth in trust for future
generations.
At the same time, we are beneficiaries entitled to use and benefit from it.
International inequity
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Of the three principles, the most difficult to apply is that of equity.
At the moment, in terms of income, the richest half, that is the high and upper-middle
income countries, are responsible for 86% of global CO2 emissions.
The bottom half, that is the low and lower-middle income countries, are responsible
for only 14%.
The UNFCCC recognises this inequity by a clause that states that, because the
industrialised countries have benefitted so much from fossil fuel burning, they should
take the lead and the first action in combating the problem and reducing emissions.
Those who impact least are impacted most
- It shows that the countries who contribute least to greenhouse gas emissions will be
most impacted by climate change.
- So, what sort of action is necessary?
Contraction and convergence
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One proposal that was put forward by the Global Commons Institute is called
Contraction and Convergence.
This figure illustrates how it works. It proposes stabilisation of atmospheric CO2 at an
agreed level. In this example, the level has been set at 450 ppmv.
This is approximately the level that would result in about a 2°C increase in global
average temperature over pre-industrial levels.
The first part of the proposal is that the world as a whole agrees to follow the
envelope curve—this is the ‘contraction’ part of the proposal.
The second part of the proposal is that eventually, from say 2030, CO2 emissions
should be allocated to countries so as to share the emissions equally between all
humans.
Between now and 2030, emissions need to converge to their 2030 allocations—this
is the ‘convergence’ part of the proposal.
This proposal recognises international equity as meaning that emissions should be
shared on a per capita basis.
This may sound completely unrealistic, but there is a third part of the proposal that
allows for trading of emissions.
Those that have more than they need can sell to those that want to emit more.
The effect of trading would be to move money from developed nations to developing
nations; that money could be used to help developing nations industrialise in sensible
ways and to develop appropriate non-fossil fuel energy systems.
There are enormous problems, political, practical, and even possibly ethical, in the
details of the Contraction and Convergence proposal, or indeed any other proposal
that can be envisaged.
But it does well to illustrate some of the essential principles that have to underlie the
necessary action and the scale and the enormous challenge it presents to all
countries of the world.
Concept quiz
Which three principles are frequently put forward as those that should govern international
action on climate change?
- Principle of equity, Polluter pays principle, Precautionary principles
Which document recognises the "equal and inalienable rights of all members of the human
family"?
- Universal Declaration of Human Rights
Mitigation strategies:
One trillion tonne carbon budget
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Let’s suppose that we want to limit global warming to 2°C over pre-industrial levels.
To achieve such a goal without negative CO2 emissions we have to limit the
cumulative amount of carbon emitted since the beginning of the Industrial Revolution
to 1 trillion tonnes. (This amounts to around 3.7 trillion tonnes of carbon dioxide.)
One trillion tonnes of carbon emitted would likely limit us to 2°C rise in temperature.
Such a limit has been argued would avoid the worst impacts of climate change.
However, recent projections have suggested that a 1.5°C limit may be required.
This figure shows the roughly linear relationship between temperature rise and
total amount of carbon emitted.
Only the very low and low greenhouse gas emissions scenarios avoid a total carbon
emission of 1 trillion tonnes being exceeded by 2050.
Keeping carbon in the ground
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The world has enough proven fossil fuel reserves to go well beyond this carbon
budget of 1 trillion tonnes.
To keep under this budget, we need to limit our future carbon consumption to about
400 billion tonnes.
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At our current pace of consumption, we will exceed the 1 trillion tonne budget by
around 2045.
Slicing up the budget
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Dividing up the carbon on the basis of GDP would leave little for developing
countries to use for their growing economies, but would give more to developed
countries, which are better able to create value from burning carbon.
Doing it on the basis of population would give developing countries a chance to
develop with fossil fuels, but it leaves little time for carbon-intensive economies to
switch to renewable energy sources.
Playing the wedge game
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The magnitude of the problem of mitigating climate change seems beyond our
capabilities.
Early debate saw the problem as needing a ‘silver bullet’: a single, optimum
technology that could be deployed to get us from today’s carbon-glutinous energy
system to the carbon-free energy system of the future.
Stephen Pacala and Robert Socolow argued that we should be using buckshot rather
than a bullet; that is, instead of finding any one single low-carbon technology to
deploy, we should be taking a more diversified approach.
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In this approach we can think of any single technology that would lower carbon
emissions as an “emissions stabilisation wedge,” which, if deployed, could by itself
avoid a modest one billion tonnes of carbon emissions per year. (We currently emit
about ten billion tonnes of carbon per year.)
While no single one-billion tonne wedge would be adequate to avoid dangerous
climate change, a combination of stabilisation wedges could be.
This figure imagines the need for nine such wedges to stabilise emissions.
How could this be achieved?
Efficiency
- Well, Pacala and Socolow recognised that the technology already exists. Such
technology wedges could be achieved through efficiency.
- For example, double the fuel efficiency of 2 billion cars from 30 to 60 miles per
gallon, decrease the number of car miles travelled by half, use best efficiency
practices in all residential and commercial buildings, or produce current coal-based
electricity with twice todays efficiency.
- Increased fuel efficiency, halve car miles travelled, more efficient buildings, improved
power plant efficiency
Fuel switching
- It could be done through fuel switching, for example, replace 1400 coal electric plants
with natural gas-powered plants.
- Substituting natural gas for coal
Carbon capture and storage
- It could be achieved through carbon capture and storage.
- For example, capture and store emissions from 800 coal electric plants,
produce hydrogen from coal at six times today’s rate and store the captured carbon,
or capture carbon from 180 coal-to-synfuels plants and store the captured CO2.
- Storage of carbon captured in power plants
- Produce hydrogen from coal and capture carbon
- Increase synfuel production and capture carbon
Nuclear
- Through nuclear, for example, by adding double the current global nuclear capacity
to replace coal-based electricity.
- Double nuclear capacity
Wind
- Through wind, for example, by increasing wind electricity capacity by 10 times
relative to today, for a total of 2 million large windmills.
- Increase wind capacity
Solar
- Through solar, for example, by installing 100 times the current capacity of solar
electricity, or by using 40,000 square kilometres of solar panels to produce hydrogen
for fuel cell cars.
- Increase solar capacity
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Biomass
- Increase ethanol production
- Through biomass fuels, for example, by increasing ethanol production 12 times by
creating biomass plantations with area equal to 1/6th of world cropland.
Natural sinks
- Eliminate tropical deforestation
- Adopt conservation tillage
- For example, by eliminating tropical deforestation, or adopting conservation tillage in
all agricultural soils worldwide.
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Although no single strategy will suffice, a combination of the technological strategies
described here will build the stabilisation required.
To get net zero
Behaviour
- However, further wedges will be required to bring the world down to no carbon
emissions.
- In addition to technology wedges, we may need behavioural wedges,
such as cutting driving in half, cutting projected meat consumption by a third,
or cutting projected miles flown by a third.
- Cut driving by half
- Cut meat consumption by a third
- Cut miles flown by a third
-
Breaking the problem down into manageable chunks does seem to provide a vision
of the possible.
Concept quiz
What is the maximum cumulative amount of carbon that can be emitted before global
warming rises above 2°C over pre-industrial levels?
- 1 trillion tonnes
Which of the following emission reduction strategies would reduce carbon emissions through
changes in behaviour as opposed to implementation of technology?
- Eat less meat
- Use public transport rather than private transport
5. Reflect on how you incorporate new knowledge into your current
understanding and on the danger of absolute certainty.
The danger of certainty
Approaching new knowledge
- How should we approach new knowledge that challenges our own preconceived
notions?
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A useful approach might be to consider Bayes’ Theorem.
The medical test paradox
- Suppose you wake up in the morning feeling a little rough and decide to visit your
GP.
- The doctor is perplexed by your symptoms and decides to run a battery of tests.
When the results come back it appears that you are positive for a rare and nasty
illness that only affects 0.1% of the population.
- Given the nastiness of the illness, but also the discomfort of the treatment, you ask
your doctor what are the chances that the test result is wrong.
- Your doctor tells you that the test will correctly identify 99% of people who have the
disease.
- So, the question is what is the chance that you do indeed have the disease. A naïve
reading might lead you to think that it is 99% certain that you have the disease, but
as you probably remember this is wrong.
- Let’s determine this critically.
0.001 (probability of getting the disease)
0.99 (probability of the rest being correct)
0.01 (100%-99% = probability of the test being false)
No. of people who will get the disease/falsely tested + No. of people who will get the disease
-
Say we have 10,000 people in a population, 0.1% of that population or 10 people will
have the disease.
But if we were to test the entire population, then 100 people would falsely test
positive (the test has a 1% false positive rate).
So that means that the chances you have the disease is 10 chances out of 110 or
about 9%. That is not very high and far lower than 99% accuracy of the test.
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So, you decide to go to another doctor who uses a different laboratory for running
tests and you ask for a second opinion. When you get the result back, it is positive
again.
What are the chances? Well let’s suppose that the two tests are independent of one
another. What would be the chances of falsely testing positive twice? That would be
1% of 1% or 0.01%.
That means in a population of 10,000 people, one person would falsely test positive
twice, but of that population 10 people still have the disease.
So, now the chances that you have the disease are 10 chances in 11 or about 91%.
As more evidence comes in we need to update our estimates as to whether
something is true, even if our perceived chance of it being true, 0.1% chance in this
example, is very small.
Concept quiz
If the frequency of disease in the population was 1% and the probability you test positive if
you have the disease is 90%, what is the probability you actually have the disease? (You
may assume that the test sensitivity and specificity are both 90%.)
No. of people who will get the disease/falsely tested + No. of people who will get the disease
0.01/0.01 + 0.1 = 8%
- 8%
Lecture 9 - Our forests, fragmentation and connectivity
Why is biodiversity important? (Sir David Attenborough video)
- Provide us with food (from soil, pollinators, fish)
- Medicine
- Shelter us
- Coastal protection from storm/flood
What should we do?
- Leave enough space for natural habitats to thrive
- Rebuild biodiversity
1. Green cover in Singapore: from ‘catastrophic extinction’ to recovery
Primeval Singapore (>700 years)
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Settlement and clearance
- 1819 – rapid deforestation with British colonisation
- 1900 – 90% of primeval forest cleared mainly for agriculture
- (e.g. pepper, gambier)
- (40% rubber plantations in 1935)
Urbanisation
- 1959 – rapid urbanisation & large-scale land reclamation with independence
- E.g. Jurong become industrialised
- 1973 – < 30% land area natural vegetation
- 1990 – > 99% of original forest lost;
> 50% Singapore is urbanised
Why is Singapore's biodiversity described as having experienced "catastrophic extinction"?
- After British colonisation, the forests and swamps experienced unregulated
exploitation mainly for agriculture.
- After independence, housing, infrastructure and manufacturing needs were achieved
by land reclamation and urbanisation.
- More than 99% of primary forests in Singapore were eliminated
Recovery, restoration, and enhancement
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City in nature builts on all the efforts that Green Singapore had in the past
Vegetation covers more than half the island
- By 2011, vegetation cover is 56%
- 29% spontaneous (non managed) vegetation (e.g. wild forest nature reserve in the
nature park)
- 27% managed vegetation (parks, gardens, lawns, etc)
- >2% old secondary + primary forest (the biodiversity core)
“A City in Nature” has a more than half-century legacy; NParks Explains: Our Greening
Journey (2021: 6:40)
- 1960 - Garden City by Lee Kuan Yew
- 1970 - Grow trees annually with the community
- Created more parks
- Park connectors
- Nature reserves are our core biodiversity areas, containing some of our last primary
rainforests, and rare mangrove and coastal habitats that provide home for native
plants and animals.
- As part of the Singapore Green Plan 2030, aims to create green, liveable and
sustainable Singapore, City in Nature builds on what we have achieved so far and
aims to restore and further integrate nature into our city.
- Aim for all households to be within a 10 mins walk from a park by 2030, and for every
road to one day become a Nature way.
- Firstly, by extending our natural capital and adding more nature parks.
- Nature parks buffer nature reserves, providing more spaces for nature-based
recreation, while minimising the disturbance to core biodiversity areas
- Also provide more habitats for our plants and animals beyond nature reserves
- Secondly, we are intensifying nature in our urban landscape including developing
gardens and parks
- Land allocated to nature parks will double.
Vegetation covers more than half the island
- Extensive connectivity between nature parks and forest reserves via park
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connectors, help wildlife recovery, and will improve genetic resilience
Nature reserve fragments are enhanced by buffer parks and habitat enhancement
A first canal is naturalised at Bishan-AMK Park!
Parks and park connectors allow recovery of adaptable wildlife
- The return of the southern pied hornbill to Singapore
Nature reserve forest fragments – increased in size, and enhanced
- Protection of Bukit Timah forest fragment with the addition of buffer parks
-
Buffer Park additions to the Nature Reserves (NParks)
-
Enhance the buffer parks!
25 Jan 2019 NParks Forest Restoration Action Plan for nature areas
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What about waterways?
- Rivers in the 1960s were sewage
- E.g. Sungei Kallang today (it was a dead river)
- Cleaned water for a drinking catchment
17 reservoirs in Singapore to collect and store rainwater and used water
The single naturalised canal at Bishan-AMK Nature Park – more?
- Not a concrete canal anymore
- Otters came back
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What about coastal and marine environments?
- There was a rich diversity, but were disappeared, catastrophic loses
- First marine park in 2014 (Sister’s island marine park)
- Growing coral reefs
- Mandai mangroves and mudflat declared a nature reserve, 2018
2. What about SGP2030 and the “City in Nature” vision?
“A Whole-of-Nation Sustainability Movement” greenplan.gov.sg
The Green Plan is a multi-agency effort spearheaded by five ministries:
1. Ministry of Education
2. Ministry of National Development
3. Ministry of Sustainability and the Environment
4. Ministry of Trade and Industry
5. Ministry of Transport
Unique:
- It is spearheaded by five ministries addressing a diversity of sustainability objectives
through five pillars.
- Biodiversity conservation solutions in A City in Nature pillar includes co-creation and
stewardship of nature by communities.
Meanwhile, there is a concern about biodiversity issues in Singapore by the nature
community
- While sustainability awareness has increased somewhat, understanding of
biodiversity is poor
- We have not prioritised protection and connecting pockets of valuable young
secondary forest where possible or retaining connectivity, i.e. business as usual.
- Advocacy has to be sustained until policy makers and planners understand the
issues
The good news from SGP2030? Biodiversity is a focal point in the new integrated approach
● Pillar 1: City in Nature
● Pillar 2: Energy Reset
● Pillar 3: Sustainable Living
● Pillar 4: Green Economy
● Pillar 5: Resilient Future
City in Nature (by 2030) Objectives
1. Conserve and restore natural ecosystems
2. Establish world-class gardens and parks with nature
3. Restore nature into the urban landscape
4. Strengthen island-wide ecological and recreational connectivity
5. Enhance veterinary care and animal management
6. Build science and technology, and industry capacity
7. Inspire communities to co-create and be stewards of nature
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3. Are all green spaces alike?
Types of green
- Grasslands - grass dominated
- Scrubland - grass + shrubs
- Woodlands - sparse tree canopy
- Forests - dominated by trees and woody vegetation
- Primary rainforest (original forest; 10% in 1900; now 0.28%)
- Mature secondary forest (later stages of growth) (e.g. macritchie)
- Young secondary forests (recovering from agriculture and settlements)
- Exotic dominated secondary forests (mostly non-native species)
Why are we concern about exotic or native?
- Aim is to achieve the standard of primary forest, and the full functioning has to be
met by native species
NParks Explains, “Different Shades of Green” (4:50)
- Grasslands
- Scrublands (has grass covers and includes scrubs)
- Woodland (can find some tree cover)
- Forest (dominated by trees and other woody vegetation)
- Tropical rainforest is the main vegetation type that is native to Singapore
- Forest consist of various layers of vegetation such as understorey, subcanopy and tall emergent layer
Development is ever ongoing…
Master Plan
-
Singapore Master Plan 2019 (reviewed every five years)
How much can we protect?
- One example is the cross island line which cuts from northeast to the southwest of
Singapore
- Possible to ensure there is connectivity, possible to have large projects coinciding
that will badly affect wildlife?
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Each surviving forest fragment faces challenges to its health
- The example of the fragmentation and high visitorship at Bukit Timah hill
- Sources of disturbance
- Road
- Paths
- Human traffic (trail compaction; illegal night walks)
- Quarries
- Condominiums (mosquito fogging)
- Compounded by size
The impact of the edge effect
- The edge of the forest is different from the core of the forest
- With the drying of forest edges, more light penetration is received, of up to several
metres (humidity drops)
- Leading to further fragmentation
- Globally, 70% of remaining forest is 1km from forest edge!
- Biodiversity reduction: 13 - 75%; and biomass reductions
Concern for BTNR’s health (suffered from edge effect)
- 1985: Scientists raised concerns in Sunday Times article (Hoe, 1985)
- 1995: Special edition of Gardens’ Bulletin on BTNR (Corlett 1995)
- 2002 & 2011: BTNR “patient under intensive care”
New NParks CEO Kenneth Er: Announcement of closure of BTNR, 2014
- Closed for 2 years
- They will open the main summit road after 6 months
- The full opening will take 2 years
Public demand was acute, so the Summit Trail was reopened
- After a closure of six months announced on June 2014,
- the Summit Trail of Bukit Timah Nature Reserve was opened to visitors
- from 4th April 2015
- on weekends from 7am-6pm (last entry at 5pm)
What’s next?
- People create impact from sheer numbers
- Wildlife stay away so effect = habitat reduction
- Erosion needs to be monitored and trails need to be pre-emptively closed for
maintenance
- Introduce zonation and alternate opening of routes? (Has been suggested)
4. Why is ecological connectivity so important in Singapore?
-
That parks and young forests will be connected with sources of greater biodiversity.
That pollinating and seed-dispersing wildlife will be able to move between areas of
source and sink.
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Our forests are fragmented
- Threats to wildlife from roads
- Our problems are similar to problems elsewhere, with larger species
- Connectivity of fragments will enhance biodiversity, but this is not yet always adopted
- Constructive consultation is ongoing
- The relevance of ecological connectivity is highlighted (2021)
- In “A City in Nature, a Greener Urban Environment”, a speech by MND
Minister Desmond Lee at the Committee of Supply Debate, Joint Segment on
Sustainability, 4th March 2021, the words “connect” and “connectivity” are
mentioned 13 times, including:
- “…a key strategy of our City in Nature vision, not just to conserve specific
pockets of greenery and nature, but to look at Singapore and our map from
an ecological connectivity point of view.
Wildlife are present in our forests and play an ecological role (ecological functions)
- The wildlife in our forests interact with other organisms and perform ecosystem
functions, including seed dispersal…
- Civet (animal) is a gardener/disperser
Wildlife moving between forests provide ecosystem functions, ensuring that the forests are
more resilient.
How well connected are habitat fragments?
● Aerial - have the capability to fly in the air
● Arboreal - live in trees
● Terrestrial
● Fossorial
● Aquatic
Types of species
Urban avoider
- confined to natural habitats
Urban adapter
- Occur at margins, or
- Partly naturalised urban areas,
- occasionally straying into urban areas
- E.g. otters, hornbill, pangolins
Urban exploiter
- E.g. commensals
Which types of wildlife are able to connect across urban barriers, and contribute to
ecosystem resilience?
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5. More help to improve fragments and connectivity – the One Million Tree
movement and the Ecological Profiling Exercise
Ecological Profiling Exercise (2020)
- A new sheriff in town – the Ecological Profiling Exercise (EPE)
- Previously development prioritises maximising development with managed planting
added after
- Each development site (e.g. state land forest fragment) is now evaluated holistically
by NParks:
- How is it linked to a source habitat? E.g. a nature reserve or a mature park
- Does it contribute to a nature corridor?
- Through the EPE, NParks had identified “source habitats” and nature corridors in the
Clementi-Ulu Pandan area.
- Findings showed that there are two main ecological connections between Bukit
Timah Nature Reserve and the Southern Ridges.
- It will establish nature corridors by identifying and linking up source and sink habitats.
- It will evaluate green sites to understand their ecological profile and potential
contribution towards ecological connectivity.
One Million Trees movement (2020)
- NUS’ planting commitment (2018) has been upgraded to planting 100,000 trees, i.e.
10% of the OMT!
- Habitat enhancement in our backyard on Kent Ridge
David Orr article
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Many of the problems were caused by people who are well educated
Lecture 10 - Restoring Green Spaces & Human-Wildlife Coexistence
1. How is the conservation of biodiversity addressed globally and nationally?
The United Nations Convention on Biological Diversity (1992)
- Formulated from 1988 to 1992
- The Convention on Biological Diversity was opened for signature on 5 June 1992 at
the United Nations Conference on Environment and Development (the Rio "Earth
Summit”)
- Singapore the CBD signed on 12 June 1992
As a result of the CBD…
- NParks announces the National Biodiversity Centre
- Singapore’s National Biodiversity Strategy and Action Plan goals
- Conserve and enhance biodiversity at the genetic, species and ecosystem
levels.
- Ensure sustainable use of Singapore’s biodiversity resources.
- Ensure fair and equitable sharing of benefits that result from the use of our
genetic resources.
- Integrates these principles into the City in Nature Vision and as a pillar into SGP2030
How has biodiversity progress since 1992 convention?
- Prof Tommy Koh drafted the Rio Declaration of Principles on Environment and
Development
Further action is needed: COP 15 (Dec 2022)
- UN Biodiversity Conference (COP 15) in Montreal, Dec 2022
- “Despite on-going efforts, biodiversity is deteriorating worldwide and this
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decline is projected to worsen with business-as-usual scenarios.
The UN Biodiversity Conference will convene governments from around the
world to agree to a new set of goals for nature over the next decade through
the Convention on Biological Diversity post-2020 framework process.
The framework sets out an ambitious plan to implement broad based action to
bring about a transformation in society’s relationship with biodiversity and to
ensure that, by 2050, the shared vision of living in harmony with nature is
fulfilled.”
Our National Biodiversity Strategies and Action Plans (NBSAP) will be updated
- We will play our part as a global citizen
- We will align our national goals
- There is space for active participation
Are youths paying attention?
- Global Youth Biodiversity Network
-
Singapore Youth Voices For Biodiversity
- Started from 2019
2. What do we know about landuse change?
Big fragment - western catchment, central catchment, pulau ubin and pulau tekong
Small fragment - nature parks
Where are our largest areas of native ecosystems in Singapore?
- The mature secondary forests of Bukit Timah and Central Catchment Nature
Reserves
- The mangrove forests at Sungei Buloh Nature Park Network and Pulau Ubin
Landscape changes around Berlayer Creek
- Dramatic changes to Singapore’s coastline led to a significant loss of coastal habitats
and their wild communities; so they are all precious, coastal and marine!
- 1930, from a sea chart of western Singapore Straits
- The freshwater swamp has been drained
- The meandering Berlayer River has been canalised, southern mangroves are intact
Berlayar Creek & Labrador Park today
1. Marginal habitats have survived and are protected.
2. Will connectivity be retained when Keppel golf course becomes a residential space?
3. Planting has been conducted as part of One Million Trees movement.
4. Is it enough?
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3. What can we do about ecosystem degradation? Connect forest fragments!
Culverts
- E.g. Connection through a road or underground is establishing a culvert
- Malayan Porcupine moved across
- Lesser false vampire bat colony in a culvert (a dry water channel)
Rope bridges
- Raffles Banded Langur uses the rope bridge (NParks)
Ecolink
- EcoLink across the BKE (2013)
- Common palm civets and pangolins using the EcoLink
- Slow Loris on an EcoLink
- Connect Bukit Timah Nature Reserve and Central Catchment Nature Reserve
- Expand habitat, genetic pool and chance of survival
4. What can we do about ecosystem degradation? Plant a tree!
What is the status of the One Million Trees movement? (launched in 2020)
- OMT was initiated during COVID-19 pandemic
- Target: 100,000 per year
- How are we doing?
How to plant a tree?
- Glove, changkol, watering can, hat, covered shoe, sunblock
- Dig hole with changkol
- tree hole = 2-3 times root ball diameter
What about growing a forest?
- Case Study Habitat Enhancement @ Kranji Coastal Nature Park
- Organised by NUS Toddycats/International Coastal Cleanup Singapore in partnership
with NParks
- It is an ongoing long-term habitat enrichment programme which has run for almost
two years.
- The programme includes soil preparation and sapling protection in addition to treeplanting.
- A lot of rubbish, forest cannot stabilise
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Coastal cleanups began, 1997
After a decade of cleanups, the mangrove is clean
Sungei Buloh Wetland Reserve Extension, 2014
A process in forests called succession: natural regeneration, but must have mature
forests nearby
However, Kranji coastal nature park was too far from mature forests
Hence, NParks came up with coastal restoration project
Partnership, not just participation
Habitat Enhancement is more than Tree-Planting
1. Soil preparation;
a. Weed clearance
b. Soil exposure
c. Soil loosening
d. Soil digging
e. Soil enhancement
f. Tree hole readiness
2. Tree-Planting;
3. Seedling Protection Activity
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Chestnut Nature Park
- Chestnut Nature Park buffers the Central Catchment Nature Reserve from edge
effects and draws recreational activities away from sensitive areas.
- Friends of Chestnut Nature Park (community restoration began in 2018)
- How to engage residents?
- How to find resident organisers?
NUS’ planting commitment (2018) has been upgraded to planting 100,000 trees, i.e. 10% of
the OMT!
- NUS will intensify its campus greening efforts and plant up to 100,000 new trees by
2030.
5. Human-Wildlife Coexistence – wildlife responds and so should we
ENSURING HUMAN-WILDLIFE COEXISTENCE
Tapping the expertise of a dedicated landscape (ground up Working Groups)
- NGOs - address the needs that was not addressed by society
- Researchers
- Interest Groups/Individuals (specialist knowledge)
Working groups
Animals that enter urban spaces
- Long-tailed macaque
- Common palm civet
- Hawksbill turtle
- Wild pigs
- Smooth-coated otter
- Raffles Banded Langur alpha male
6. Biodiversity conservation for climate change requires more than science
Growing the community through shared use and forest stewardship (taking care of
something)
- Stakeholders
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Residents and brisk walkers
Nature enthusiasts
BMX & Mountain cyclists
Forest restoration groups
As a result of the CBD (Convention of Biological Diversity)
- Singapore’s 4th National Biodiversity Strategy and Action Plan (2019):
- NParks announces the National Biodiversity Centre
- Singapore’s National Biodiversity Strategy and Action Plan goals (report to the United
Nations documents)
- Conserve and enhance biodiversity at the genetic, species and ecosystem
levels.
- Ensure sustainable use of Singapore’s biodiversity resources.
- Ensure fair and equitable sharing of benefits that result from the use of our
genetic resources.
- Integrates these principles into the City in Nature Vision and as a pillar into SGP2030
(NParks shared this as the Nature Conservation Master Plan (2015) and added
“Community Stewardship and Outreach in Nature”)
Lecture 11 - Climate Change, the Hinterland and the Sustainable City Dweller
1. What is the problem, and what contributes?
Giants of the past
- Dominant and large plants of the Carboniferous Period (359 – 299 million years ago)
during the late Paleozoic Era.
- E.g. Tree ferns and lycopod trees
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Coupled with accelerated resource extraction
-
Species extinction
Loss of forest productivity which can affect how much nutrients you can extract from
natural systems
One example of exploitation is fisheries exploitation
What are the sources which emit carbon dioxide? What generates greenhouse gas
emissions?
-
Almost threequarters of emissions come from energy use
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Almost one-fifth from agriculture and land use; onequarter for food system as a whole
[+ processing, packaging, transport and retail]
The remaining 8% from industry and waste
global greenhouse gas emissions
The impact is not felt by emissions alone…
- E.g. Deforestation (2.2%): net emissions of carbon dioxide from changes in forestry
cover.
- But biodiversity loss results in flooding, erosion, loss of ecosystem services (air,
water, soil); timber, medicines, raw materials, fuel, etc [the previous lecture]
2. Inequalities of Climate Change: considering emissions in perspective
Who consumes? [Countries]
Ecological Deficit
- An ecological deficit occurs when the footprint of a population exceeds the
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biocapacity of the area available to that population
-
Singapore is small and import a lot of things
Who consumes?
-
Shows us that our footprint is high compared to other countries
It is the lower-economy countries which are not the cause of problem and the overconsumption is from the developed countries
Correlation of ecological footprint (2008) and the human development index (2012)
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Socio-economic status (looking at socio-economic groups within countries)
The starkly different contributions of different income groups to carbon emissions
- "Polluter elite”
- The world's wealthiest 10% were responsible for around half of global
emissions
- The top 1% were responsible for 15% of emissions, nearly twice as much as
the world's poorest 50%
- “The richest of the rich are polluting the world and driving climate change, while the
poorest of the poor suffer the greatest consequences”
- "The bigger your carbon footprint, the bigger your moral duty” - Greta Thunberg
(2019)
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Part of a global elite?
- Flying – more than 90% of people have never flown and just 1% of the world's
population is responsible for 50% of emissions from flying.
- SUVs – make up 42% of global car sales in 2019, and were the only sector to see
emissions rise in 2020 – the increase in people buying SUVs in 2020 cancelled out
the climate gains of electric cars.
Coastal Cities
- Higher risks for coastal cities
Disproportionate risk is on the agenda (countries are fighting for their rights)
Inherent inequities of climate change impact
- “it is the populations of these economies most vulnerable to climate change who
contribute the least to the accumulation of greenhouse gases”
- In framing the objective of holding the increase in the global average temperature
rise to well below 2°C above pre-industrial levels, and to pursue efforts to limit
warming to 1.5°C,
- the Paris Agreement associates the principle of equity with the broader goals of
poverty eradication and sustainable development,
- recognising that effective responses to climate change require a global collective
effort that may be guided by the 2015 United Nations Sustainable Development
Goals.
What factors does the topic of inequities of climate change consider?
- The development history of countries over the past few centuries.
- Contributors of present-day carbon dioxide concentrations in the atmosphere.
- Vulnerability to sea level rise.
3. What is the hinterland? And its particular significance to Singapore
The hinterland
- the remote areas of a country away from the coast or the banks of major rivers.
- the rural area economically tied to an urban catchment area
- “a large, powerful urban community (metropolis) and the surrounding territory
(hinterland) which the metropolis dominates through mainly economic means”
A city and its hinterland
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Singapore is a city-state, rarely have rural hinterland
-
Jakarta is sinking in parts because people extract fresh water
As you approach the city, the urban index is higher until the city is almost devoid of
natural landscape
Singapore’s hinterland?
-
Need look at larger area of Southeast Asia
Our hinterland is global
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The productive areas of the world which can supply our needs.
Some local production which complements global supply in a small way.
4. Singapore: what spaces are we dependent on?
Food
- 2019 – As a result of climate change and rising population, the world is set to face a
56 per cent shortfall in food nutrition by 2050.
- The latest report warned that the shortfall in food needed to feed the world in 2050 is
likely to be exacerbated by a global shortage of nearly 600 million hectares of
agricultural land
Singapore’s food security
- Increase production of vegetables, fruit, poultry and fish
- Import over 90% of food supply
- Vulnerable to disruptions in transport routes, export bans, climate change
- Redundancy in supply
Where do we get our food? 82% imported over 170 countries
How do Singapore remain food secure?
- Political/Economic/ Legal
- Technology
- Social
Examples of countries Singapore import food from
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What food targets are there in the Singapore Green Plan (SGP2030)?
- Meet 30% of Singapore’s nutritional needs through locally produced food
- Without hinterland, we import everything
Water
World Meteorological Organization’s State of Climate Services (05 Oct 2021)
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Competition for water
Over the past 20 years, terrestrial water storage has declined by 1cm per year
2015 El Niño
- Singapore consumes 400 million gallons of water a day
- During the 2015 El Niño, three districts in neighbouring Johor underwent waterrationing in August to September 2015, affecting more than 640,000 industrial and
household consumers for a month.
- In Singapore, the desalination and NEWater plants under Public Utilities Board
increased freshwater production to tide us over, so few people noticed the water
shortage.
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Want to reduce water importation
By 2010, we have 17 reservoirs
Are there water targets in the Singapore Green Plan (SGP2030)?
- Reduce household water consumption to 130 litres per capita per day
- Singapore’s first integrated waste and used water treatment facility to be 100%
energy self-sufficient (Tuas Nexus)
Energy
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Are there energy targets in the Singapore Green Plan (SGP2030)?
- Singapore as a leading centre for green finance and services to facilitate Asia’s
transition to a low-carbon and sustainable future
- Singapore as a carbon services hub in Asia
5. What can we do?
Since 2018, more than half the world’s population live in cities: is this a liability or an asset?
SDGs: a to-do list for the world
- The Sustainable Development Goals (SDGs) are a set of goal under the 2030
Agenda for Sustainable Development (2030 Agenda), which is a global development
framework adopted by World Leaders at the UN Sustainable Development Summit in
September 2015.
- It comprises 17 SDGs with 169 targets and there are currently 247 indicators used to
measure progress towards reaching the targets.
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The 2030 Agenda for Sustainable Development
- Adopted by all United Nations Member States in 2015
Cannot achieve goals so more meetings to achieve resolve – COP27
Six key issues at #COP27, the 2022 United Nations Climate Change Conference
1. Mitigation Work Plan
2. Climate Finance
3. Adaptation
4. Loss and Damage
5. Biodiversity
6. Carbon Markets
6. What can I do?
Action for change: learn, then enhance your impact
- Live a sustainable lifestyle, and learn practical methods
- Promote practises, share information
- Become part of a community for enhancement and support
- Amplify – addressing issues in your work place or community
- Participate to suggest practises at higher levels, e.g. Singapore Green Plan
Conversations
SGP2030, 01 Feb 2021
- “A Whole-of-Nation Sustainability Movement” greenplan.gov.sg
- The Green Plan is a multi-agency effort spearheaded by five ministries:
- Ministry of Education
- Ministry of National Development
- Ministry of Sustainability and the Environment
- Ministry of Trade and Industry
- Ministry of Transport
Bill Gates looks at the numbers…
- Examines the numbers, looks for technological breakthroughs and policy
introductions and changes (investment and innovation)
- “Show me a problem and I’d look for a technology to fix it”
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Governments? “I don’t have a solution to the politics of climate change”
Acknowledges everyone will need to change their mindsets and behaviour
Young people are the driving force; and people will have to talk about the threat of
climate change with friends and family members too
Address it professionally, via jobs
Lecture 12 - Fallacies in the Name of Science & Module Wrap Up
1. Provide examples of scientific inquiry within the area of climate change by
relating concepts and/or content from block 2 of this module to block 1.
Lecture 1
Observe, test, explain
What does it mean for a theoretician?
- A theoretician was someone who developed testable theories.
- Nowadays, a great deal of the work of a theoretician is putting together
mathematical, and indeed, computer models.
- These models make predictions that can be tested against observation.
- So, within the context of the observe, explain, and test paradigm, theoreticians are in
the business of explaining and testing, but leave observation to scientists skilled in
this area.
- E.g. In lecture 5 (Figure 1, video here.), I spoke about Fourier who was the first to
realise that we cannot explain the temperature of the Earth surface if we do not
consider the atmosphere.
- His early studies had found that if we only considered radiation from the sun or from
the interior of the planet the Earth would be much cooler than it is.
- He correctly identified that the atmosphere must play a role, and he did this by
making use of a metaphor.
- He said that “the Earth is kept warm because air traps heat, as if under a pane of
glass”.
- We now know that this is not quite right, but the essential element that we need to
consider the atmosphere was correct
Authority
Are experts always right? Should we just take their word for it?
- I felt that I needed to point out that consensus in science is different from how we use
the term colloquially.
- In science, it isn’t just a general agreement of opinion.
- Rather in science, a consensus is achieved when the great majority of scientists of a
given field agree upon a position based on a large amount of verified evidence.
- The process of verifying evidence is critical. This goes to the heart of what science is,
that something can only be science if it is verifiable.
- Scientific consensus is not an argument from authority
- "Authority" means "expert in the field"
- E.g. We also saw how authority can be abused. I spoke of the role played by John
Sununu, the Chief of Staff in the George H. W. Bush White House, who attempted to
undermine the work of climate scientists and ultimately the international community in
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fighting climate change. He argued from authority that global warming was
“poppycock”.
E.g. But it isn’t just educated people in the wrong field. I would argue that Sununu
did not have the required authority (i.e., expertise) to speak on issues of climate
change. However, I also introduced the statements of Richard Lindzen (Figure 3,
video here), who is a professional climate scientist. I would absolutely argue that
Lindzen has the authority (i.e., expertise) to speak on issues of climate change. And
it is important that his voice is heard.
However, his ideas for a solar source to rising temperatures are not confirmed by
experiment and so his ideas are not part of the scientific consensus. Authority and
consensus are different.
Scientific revolution
- There are also scientific revolutions within disciplines, noted by Thomas Kuhn
- So, I spoke about how the paradigm found in the alchemical writings of Becher and
Stahl were replaced with the ideas of Lavoisier.
- This transformation in thinking led to the development of chemistry as a rational and
distinct scientific discipline.
- This chemical revolution centred on understanding the nature of oxygen, and in
particular, the role that oxygen plays in combustion.
- Lavoisier established our modern understanding of combustion through recognizing
that mass is conserved, that the oxygen lost from air during combustion of a metal
can be found in the metal oxide product. The law of conservation of mass underpins
all of chemistry which is why Lavoisier is rightly called the Father of Chemistry.
New instruments, new discoveries
- Galileo during the scientific revolution that a common feature we see in science is the
invention of a new instrument to observe nature and this leads to band new
discoveries.
- Now in the case of Galileo it was his much more powerful telescope than anyone
else at the time, right?
- It was 30-times telescope compared to 3-times that everyone else was using. Now
we also see this type of thing illustrated in your section.
- E.g. Although I didn’t speak too much about this, but the ratio spectrophotometer
built by Tyndall (Figure 5, video here) for example was critical in determining the
relative importance of different greenhouse gases.
- E.g. However, perhaps the most important instrument in climate science has been
the computer. The first attempt at performing a meteorological forecast through
computation was conducted by Lewis Fry Richardson in 1922, well before the advent
of the modern computer.
- Not only did his 6-hour forecast take months to calculate, but it was also so grossly in
error that no one repeated such calculations for 30 years.
- Without computers, and in particular, the supercomputers used in climate modelling
(Figure 6, video here), we would not be able to project the effects of climate change.
- It would simply not be possible to couple together all of the different parts of the Earth
system, or indeed even understand isolated elements of the Earth system.
Scientific community
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A scientific community is a prerequisite for the emergence of consensus.
The scientific societies that arose during the scientific revolution became the model
for open and frank discourse that still exists today.
It was climate scientists being brought together to evaluate the emerging evidence
that led to the consensus position around climate change.
E.g. I know you spoke about the Royal Society of London as an early example of
such a scientific society.
The Royal Society was greatly influenced by many figures including Francis Bacon,
and in particular his vision of experimental science.
When I think about the environment, I am reminded that is was Bacon who stated
that the ultimate goal of scientific inquiry was power over nature.
I fear really that this tradition is responsible for the current state of our climate.
Industrial revolution
- The reason why we use the average between 1850 and 1900 as the proxy for preindustrial temperatures is for two reasons: First, we don't have reliable instrumental
records to construct a global average prior to this; and second, we don't believe that
carbon dioxide emissions from the coal burnt between the advent of the industrial
revolution and this period would have had any significant influence on global
temperatures.
Scientific observations
Have we considered all the necessary comparative information?
- We subtracted baseline temperatures, such as the 1850–1900 average, from global
temperature measurements to reveal changes in temperature.
- We also compared carbon dioxide, methane, nitrous oxide measurements other
greenhouse gases to past levels to reveal differences.
- These were used to argue that global warming was happening and that the
suspected cause, that is greenhouse gases, were also increasing.
Lecture 2
Where does most of the evidence lie?
Some examples in block 2
- there wasn't a single go to instrumental temperature record.
- E.g.In fact, we discussed four datasets. Those of NASA, NOAA, the UK Met Office
and the Japan Meteorological Agency.
- These organisations all treated the data slightly differently and thus produced slightly
different temperature records.
- However, they all agreed extremely well and certainly showed that global average
temperatures are increasing.
- I think it is vital that we allow for these different perspectives for the treatment of data.
- Now when looking at whether recently temperature rises were unusual, scientists
looked for ways of estimating temperature prior to the instrumental temperature
record.
- This required scientists to take really some quite novel approaches. Some really
quite clever science allowed scientists to develop temperature records from proxy
methods, including those developed from tree rings, coral rings and ice cores.
- The important thing here is that all of these proxy methods are in agreement and
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indeed show that the rapid increase in temperature since the industrial revolution is
unprecedented at least in the last several thousand years.
In the same way I suppose, we do not rely on a single organisation's instrumental
temperature record, we also do not rely on one research group's climate models.
The projections and analysis found in the IPCC Sixth Assessment Report came from
some 100 climate models themselves developed by I think 49 distinct research
groups.
The preponderance of evidence from these model simulations is that, amongst other
things, global temperatures will continue to increase, that sea levels will continue to
rise, that ocean pH will continue to fall, and that Arctic sea ice will continue to decline.
I suppose another way in which the preponderance of evidence argues that climate
change is happening was also argued when I showed the human fingerprints on
climate change.
Again we are not relying on single pieces of evidence we are looking at evidence
found throughout the Earth system.
This convergence of evidence is part of the process of verification and really goes at
the establishment of scientific consensus.
Testing an explanation
Has anyone tried to disprove the claim? E.g. from block 2
- Scientists have tried to disprove the claims that climate change is happening.
- They see this as being part of their duty. And indeed that climate change is human
caused.
- Scientists have studied whether the temperature increase that we see could be
natural variability, but the evidence is simply not there.
- Scientists have attempted to prove that the temperature increase is due to solar
variability and changes in volcanic activity, and again the evidence to support such
ideas is not there.
- The only explanation that scientists have failed to disprove is that the increase in
temperature is due to the increase in greenhouse gases, and in particular, carbon
dioxide.
- Scientists have also attempted to prove that the increase in carbon dioxide is not
human caused, but a variety of evidence has shown to us that it is.
- E.g. In lecture 6 for instance, I discussed the dilution of carbon-14, the radioactive
isotop of carbon, or more accurately the ratio of carbon-14 to carbon-12, this was of
course in the atmosphere after the open-air testing of atomic weapons.
- The rate of dilution of the ratio of carbon-14 to carbon-12 can only be explained by
the emission of carbon dioxide through the burning of fossil fuels which are
necessarily devoid in carbon-14.
- In fact, the amount of carbon dioxide released through the burning of fossil fuels is
exactly that required to achieve the dilution observed. Incredibly powerful evidence
that the increases in carbon dioxide in the atmosphere is indeed due to the burning of
fossil fuels.
Misinformation, falsehoods, and lies
- What was so disturbing about my recount of the history of climate change denial was
the influence of political lobbyists and how this influence permeated into the political
discourse.
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E.g. We understand the vested interests of the fossil fuel industry, but doubt
mongering by political lobbyists and contrarian scientists deeply damaged the
prospects of action.
The advent of the internet in the 1990s and more recently 24/7 news cycle, and really
the pervasiveness of social media have deeply divided opinion on a topic in which
there is no serious debate in the scientific community.
I further spoke about how the political lobbyists were able to mainstream their
contrarian positions using techniques they had picked up in the fight to limit
regulation of the tobacco industry.
One of the most important things I hope you have learnt from this module is that we
all have biases, we are all susceptible to these biases, but recognizing that you have
biases and are susceptible is the first step to critically evaluating information that you
might well prefer to deny.
Lecture 3
Theories and hypothesis
How a theory develops, then replaced in block 2. Letting one's expectations and beliefs get
in the way of observation.
- E.g. phlogiston theory of combustion.
- The phlogiston theory states, for example, that a metal is made of what Becher and
Stahl called calx, or the metal's true form, and phlogiston, so those two together.
- When the metal is heated the calx is revealed and the phlogiston is seen to leave the
metal.
- At the time, this was a very popular scientific theory. After all when you burn stuff you
do see smoke given off and this was argued to be the phlogiston.
- Early indications that there might be problems with the theory were found in the
numerous studies, not least those by Boyle back in 1673, Lémery in 1675, and
Freind in 1709, they all showed that the metal gained weight on heating.
- The advocates of phlogiston theory attempted to argue that the phlogiston liberated
in combustion has negative in weight.
- Phlogiston theory also limited a proper understanding of the role of oxygen in
combustion.
- We celebrate Lavoisier because he was able to see clearly and recognize that
combustion is solely about the reaction with oxygen.
- Many celebrated scientists did not see as clearly, blinded as they were really by their
adherence to this phlogiston theory.
- Lavoisier's theory explained the appearance of water for instance when we burn
hydrogen and it also helped in our understanding of respiration.
Cause and effect, casual mechanisms
- It was the reason why James Hansen at the Senate hearing in 1988 wanted to state
a cause and effect relationship that existed between the greenhouse effect and
observed warming.
- E.g. I made the observation that global warming is the cause and climate change is
the effect; that the heating of the Earth system is affecting changes in many different
areas.
- When I introduced feedback and feedback loops, I spoke about how different
elements can be connected to one another.
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I spoke of negative couplings in which if the source element increases the element it
is connected to decreases. This is a negative correlation. Similarly, positive couplings
describe situations in which elements are positively correlated.
These couplings directly describe the cause and effect relationships and the
feedback loops really describe forms of causal mechanisms.
If you'll remember I also spoke about the danger in not recognizing that certain
effects can have many causes. If you believe that a certain effect can only have a
single cause, you can fall victim really of the single cause fallacy.
This was used by climate change deniers to argue that because climate change in
the deep past has happened, the climate change that is happening now can't be due
to us.
Underlying processes, laws, and functions
- E.g. I frequently referred to underlying processes. When we spoke about the
greenhouse effect I noted that it was the greenhouse gases, such as carbon dioxide,
that absorb long-wave infra-red radiation from the Earth and prevents that radiation
escaping to space.
- The role of carbon dioxide in absorbing such radiation is an underlying process and
was discussed by both John Tyndall and Eunice Foote.
- I know you also introduced the use statistical law to explain things.
- As you noted, this is particular evident when studying human behaviour. I relied on
this when I suggested that we are all susceptible to cognitive biases.
- I meant this, of course, in a statistical sense. Some people might be more susceptible
to self-serving bias, others to time-discounting bias.
- Finally, I also used function to explain things. For example, I spoke about the function
of plants in the carbon cycle. Plants take up carbon dioxide from the atmosphere in
order to photosynthesise. Plants also function as the source of food for certain
animals.
Correlation
- E.g. I think perhaps when I spoke about proxy methods, there are correlations
between the different methods, such as the tree-ring widths or coral band widths and
temperature.
- Perhaps though, the most stunning correlation that I shared was the video of the
breathing earth. We saw the seasonal variation in atmospheric carbon dioxide
negatively correlating with the rates of photosynthesis in the biosphere, particularly
the northern hemisphere forests.
- Correlations are also used by climate change deniers. The apparent positive
correlation between temperature and solar variation up until around 1980 was used
to argue that global warming was natural and due to changes in solar radiation.
- Of course, the positive correlation has disappeared in the last 30 years and if
anything there is a negative correlation now which is a little bit inconvenient for our
denialist friends.
Scientific models
Anything to add regarding models that was already well discussed in block 2?
- One point that I could have mentioned though is that mathematical models, like the
single-layer atmosphere model that I introduced are not really used to do real
science, their primary purpose nowadays is for teaching purposes, which is why I
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introduced it in my lecture.
Nowadays, virtually all models are computer models.
The phenomena that models are designed to explain are so complex that they can
only be modelled in computer simulations.
Lecture 4
Contemporary scientific research
Research isn't free, are the supercomputers expensive, and what's their C footprint like?
- These supercomputers are extremely expensive and their energy costs are very
demanding.
- Indeed, scientists are beginning to be concerned as to whether the carbon footprint
of completing a climate model simulation is ethically sound.
- Unless the simulation can truly add something to our understanding of climate
science or how climate change will evolve, it may be morally wrong to actually do the
simulation
Uncertainty and confidence levels
- When it came into the discussion for instance of whether we had seen climate
change in the late 1980s.
- James Hansen argued on the basis of the magnitude of natural variability that it was
virtually certain that climate change had happened.
- Another interesting issue that arose was in the language used in the IPCC reports.
- There was a conscious effort by climate scientists to convert the jargon around
confidence and likelihood into language that could be readily understood particularly
by policy makers and this is the reason why terminology like "very likely" and
"virtually certain" was introduced and how that was equated to the probability of
occurring.
Concept quiz
The period between 1850 - 1900 is used as a proxy for preindustrial global temperatures.
Choose two reasons why.
- No reliable instrumental records available prior to this period.
- It is highly unlikely that the coal burnt prior to the proxy period would have any
significant impact on global average temperatures.
What do tree ring widths correlate well with?
- Surrounding temperature
We noted in the video that scientists were blinded by their own expectations or beliefs. What
was this referring to?
- Adherence to phlogiston theory when evidence suggested it had issues.
2. Illustrate with examples how science has been used to inform climate-changerelated and/or biodiversity-related public policy, public works, infrastructure or
public spaces.
Field trip and scientific observations
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Did students overlook anything?
- So, the topic of your question falls to the design of the experiment. Given that these
observations are being carried out by novice observers, you don't make it
complicated.
- From the data that the earlier students taking this module gathered, we were able to
demonstrate quite clearly the differences between nature reserve and nature park.
- If a professional scientist was going to go out and make these sorts of observations
how would they do it differently?
- Well actually the fundamental approach to measuring the plants would be the same.
- There would probably be more randomization, more samples, but fundamentally it is
getting a sample of some vegetation, and comparing it.
- But in terms of wildlife, which gives you an added dimension, then that would have
required a lot of work.
- You got to look at the size of the forest - look at quadrats you can place, and then set
up camera traps because you can't do direct observations; bird counts will require
expertise, so those are really involved designs.
- This approach of using a large number of people making simple observations is
called "citizen science", and it's used increasingly by scientists around the world for
diversity of measurements.
Ecological connectivity study
How does this ecological study relate to the scientific method?
- When conducting scientific research, it is critical that terms in the original question
under investigation are clearly defined.
- The word "connectivity" is easily used, but a scientist will always scrutinize a term, or
an idea. It kind of relates back to Baloney Toolkit, they are not looking for baloney,
they are looking to see whether the science behind the term is rigorous.
- And what we realize is that connectivity often is referring to birds.
- So birds can fly, hop, skip, jump, and a open field like this is not really an obstacle
- to them. A road or a highway isn't an obstacle, but to every other animal within the
community these are serious obstacles.
- So we don't qualify the term and we are using it carelessly, in 50 years time there'll
be a lot of scientists who will curse us because we put up happily and said we've
connected all the habitats, but we haven't.
- The animals that climb in the treetops, you know the arboreal creatures, the ones
that are running along the ground, terrestrial creatures, the ones that are digging,
fossorial, let alone the aquatic - they don't have a hope in hell of crossing these
obstacles.
- But if you use the word connectivity carelessly then it's going to be a problem.
- They then evaluated the different kinds of animals and what they are likely to face as
an obstacle and then deduced whether or not the green spaces were truly connected
– and it's a grimmer truth than we realize.
- This scrutiny is appreciated by government, so they put us into a Scientific Advisory
Committee and now ask, "This is a plan, what do you think?" And when we start to
point out the loopholes they love it because what they want is a robust plan. They
don't want a short cut that's going to turn out to be nonsense in the future.
- So, the process of scientific inquiry, asking this question, criticizing the method, you
know all this scrutiny is part of a toolkit that is well respected, i.e., the scientific
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method. Basically, we must conduct an objective disassembly of an idea so it can be
clearly studied and understood, and this is now highly appreciated and welcome.
Singapore as a petri dish - testing hypothesis in a grand scale
- In tiny Singapore there are experiments that you can conduct, there are programs
you can roll out, and then when you study the effect it is applicable elsewhere.
- And so from our experiences in Singapore with biodiversity connectivity,
reforestation, there are plenty of lessons for other spaces because we are not so
different.
- And the "what next" from small plots in Singapore where we've tried things, give a lot
of hope and encouragement and ideas about how to fix things in other larger nations.
- Of course, when they scale up they're going to have to account for their larger size,
and may have to come up with new ideas to fit that.
- But for these other nations to get that primer they need we are really suitable as a
test bed because we can get things done quite quickly.
- This happens because of the small nature of our field sites and the tremendous high
access to a government that listens, and fast and easy access to other scientists, as
well as excellent essential resources like a great library and so on.
- So, even if you're in a small country like Singapore you shouldn't hesitate to try things
out - there're valuable lessons to be learnt.
Science and society
Determine the extent to which science influences and is influenced by society in the context
of climate change.
Evaluate how scientific knowledge informs climate-change-related and biodiversity-related
public policy.
- From the outset, very early on, there's been an interministerial committee on climatechange, and they do very rigorous work. Whenever we bring up ideas, I find that if it's
evidence-based, it is received with a lot of appreciation because they want to get it
right as they recognize that a scientific approach is the best chance of having that
happen.
- If you are pointing out things to the government, and doing that in a rational, scientific
manner, this means that the nature of the interaction tends to be very civilized – we
don't bang the table – we make the points clearly to them.
- On the other hand, we can be so stubborn if things don't make any sense. Then we
ask them, "What is the basis of these observations?", and we can then get to the
core of the issues quickly. It's a very healthy process that has advanced Science
here.
- There are plenty of examples of how science progresses due to the intensive
interaction of all those people that you mentioned in your block, or in block two where
Adrian talks about what are the fundamentals that explain what are the factors driving
climate-change, so it's not so mysterious.
- Unfortunately, if you have an agenda-driven industry pushing misinformation, that's a
really big challenge for educators overseas in the West because they're having to
fight all of that. I'm really glad in Singapore, that is not what has had to consume our
time.
- We invest our time in how to go about fixing things. Of course, this means that the
burden of proof is on you, as it should be, because that’s how science works. These
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interactions are not a coffee shop talk.
The government and public service here are cognizant of how and why science
works. There are ideas which they will draw on from expert opinion, but then after
that they need to test it; this is the scientific method in action at the government level.
Bishan-Ang Mo Kio naturalized canal.
You see, all around Singapore there are canals, and this is one canal that the
government said, "OK. We hear you about flood control being possible when we
return to the natural state, but how do we return to the natural state?". Well let's
naturalize the canal, it's not going to be complete return, but will that cause
problems?
Concept quiz
Which of the following was used as a good example in the WrapUp.2 video of how science
and scientists were utilized in building infrastructure in Singapore?
- Bishan-Ang Mo Kio naturalized canal
In workshop 3, discussed in WrapUp.2 video, "students considered green spaces and a map
and they looked at all of the infrastructure on the ground. They then evaluated the different
kinds of animals and what they are likely to face as an obstacle and then deduced whether
or not the green spaces were truly connected". Which part of the more detailed scientific
method, shown here, that is part of contemporary scientific research best characterizes the
quoted activity above? (Note that in some sense the activity could be thought of as "testing
with experiment", but here focus more on the actual performance of the activity.)
- Analyze data
Which of the following best describes "citizen science"?
- Scientific research conducted by amateur, or nonprofessional, scientists.
3. Describe each of the eight fallacies put forth in the name of science, providing
examples to illustrate their meaning.
-
fallacy here is either flawed reasoning or logic, incorrect or improper use of the
scientific method or a deliberate act to misrepresent something.
a. False anomalies
- will typically fraudulently present some phenomenon as being mysterious, not
explicable by science, then provide their own explanation for the phenomenon, which
is very often an extraordinary claim.
- However, the slight-of-hand occurs when they purposefully leave out evidence
in support of a regular scientific explanation, or worse, misrepresent or falsify
evidence in support of their own extraordinary claim.
- Our textbook gives us numerous examples of this, so I'll only mention one in a bit of
detail here, and that is "crop circles".
- These things are large, symmetrical, geometric figures, circular and otherwise as
shown here.
- They have "mysteriously" appeared in wheat and corn fields in Southern England
and have since been observed in many other countries.
- These mysterious strange shapes are made out to be anomalies with advocates
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suggesting there is no explanation for how they could be generated.
The patterns are typically found in the middle of crop fields where there were no
obvious signs of human intrusion.
Then the extraordinary claim is made that the patters were made by aliens or their
spaceships.
However, what is purposefully disregarded are "tramlines", seen in this figure, which
are either near or even run through these patterns.
These tramlines are indentations made by tractors as they travel through the crop
fields.
It has been clearly demonstrated that a hoaxer can simply walk down these
tramlines, and with a few simple tools, create these circles quickly and easily.
Indeed, several hoaxes have come forward and admitted and demonstrated just this.
Neglecting to mention this additional evidence creates a "mystery" when there isn't
one.
And then they go on to make wild untested explanations without evidence for how
these patterns might have otherwise been created.
b. Questionable arguments by elimination
Is the claimant providing positive evidence?
- Here the claimant consider evidence that an alternative explanation is wrong to be
actual evidence in support of their explanation for some phenomenon.
- As an example, let's consider extrasensory perception, or ESP.
- Often a strategy used to "prove" that someone can read another person's mind is to
simply show that their ability can not be explained by random guessing, or luck.
- For example, let’s say a so-called ESP sensitive can tell what playing card someone
else is looking at more frequently than chance. Even under tightly controlled
experimental conditions if this were so, it does rule out the possibility of luck at
guessing the card, but it does NOT prove that the person has ESP.
- This would only be the case if there were only two possible explanations for what is
observed (1) The claimant has ESP and (2) the claimant is just lucky at guessing the
cards. By eliminating the luck explanation does not provide positive evidence for
ESP.
- What we can NOT conclude here is that we HAVE evidence for ANY explanation for
the phenomenon yet – all we have shown is that luck isn't the explanation - that's all.
- So just by eliminating rival explanations doesn't provide evidence for your favourite
explanation.
- One needs to find positive evidence directly in support of it.
c. Illicit causal inferences
- We encountered examples of this already when we learnt that correlation doesn't
imply causation some out of the ordinary occurrence precedes some other out of the
ordinary occurrence, so you jump to the conclusion that that there is some causal link
between the two, but is there really?
- E.g. unusual occurrence directly precedes another unusual occurrence
- just because you enter a lift as someone exits it and then you smell something quite
bad in the lift doesn't mean that the person that just left the lift had anything to do
with the stench. This is another illicit causal inference.
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d. Unsupported analogies and similarities
- The fact that an explanation works in one case is given as evidence for the
correctness of a similar explanation in another case.
- E.g. An argument sometimes used in astrology
- As an example of this we use a quote from the textbook on astrology, which is a
pseudoscience. Astronomy is science normally, but astrology is not. Astrology
proports that the positions of the stars and planets at the time of our birth can
influence our personalities or even our choices of profession.
- So, because the moon influences the tides on Earth, which it does, and sunspot
activity can disturb radio transmissions on Earth, which it does, we can conclude that
the positions of the planets have an important influence on formation of the human
personality? Of course not.
- There is zero evidence to be found in the analogy and similarity that the positions of
the planets have any important influence on the formation of the human personality.
e. Untestable explanations and predictions
- "fate" as being an explanation for something occurring, or the "dragon in my flat"
conversation with Prof Lee.
- Remember, if an explanation cannot be experimentally shown to be false, then it isn't
a scientific explanation.
- We should always ask ourselves when accepting some explanation for something,
the following question: "Under what conditions would we be willing to set aside the
explanation on the grounds that it is false?"
- If you can't think of any such conditions, then the explanation you have isn't a
scientific explanation.
- Interestingly, many conspiracy "theories" fall under this category, and in fact, they
can seem attractive and even plausible because they are immune to falsification.
- They can be circular in their "evidence" for their theory, like the typical nine-eleven
conspiracy theories described in our textbook.
- You see, these "theorists" believe that they have uncovered various anomalies in the
nine-eleven attacks, then provide an explanation involving powerful government
conspirators, and when asked for evidence of this they simply rehash the anomalies
they believe they uncovered in the first place.
- There is no body of independent evidence here. An anomaly isn't evidence.
- It's an anomaly that requires a falsifiable explanation. Any real evidence that their
theory is wrong is claimed to be fabricated by the conspirators, and lack of evidence
they also claim IS actual evidence of their conspiracy because all the evidence has
been disposed of and covered up!
- Such explanations are not scientific as they are not falsifiable.
- Pseudoscience dismisses valid counter arguments to its claims or explanations on
the basis that those criticizing it are not willing to consider the possibility that their
claim or expectation is correct.
f.
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Empty jargon
Used to convince people that something is scientifically proven but isn’t.
Science itself is full of jargon, which exists so that communication between scientists
can be brief without having to constantly explain concepts and objects the jargon
represents.
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However, conmen can highjack this language and string together a bunch of terms,
which means nothing, in order to try and convince you that something is scientifically
established.
g. Ad hoc rescues
- referring to a situation where a scientific test of an explanation or claim continues to
fail those tests.
- an attempt to still accept something to be true despite now quite a lot of evidence that
it isn't.
- We now have to ask if there's any point where we will admit our explanation or claim
is false?
- If not, there this explanation or claim is untestable and thus not scientific.
h. Exploiting uncertainty
- doubt mongering around well-established causal links between lung cancer and
cigarette smoking, CFC emissions and the stratospheric ozone hole, even the link
between UVB radiation and skin cancer and SO2 emissions from coal burning power
plants producing acid rain that in turn destroys forests, and finally attacking climate
change.
- However, just because something isn't 100.000…% certain doesn't mean that it isn't
certain for all practical purposes.
- It’s the merchants of doubt that want to recast tiny levels of uncertainty into large
ones – turning somethings that has 99.99% confident into a 50-50 conclusion either
way.
Concept quiz
Sherlock Holmes is known for the quote: "When you have eliminated the impossible,
whatever remains, however improbable, must be the truth?” Which fallacy is this in danger of
running afoul? (Refer to the video for the numbering.)
- 2
A group of pregnant mothers claimed to possess a strong intuition of the gender of their
baby. An experiment was conducted and it was demonstrated that at the 95% confidence
level pure guesswork could be eliminated as an explanation for their claimed ability. The
experimenters concluded that it is true that this group of women possess this amazing ability,
at least at the 95% confidence level. Which fallacy is violated in making this conclusion?
(Refer to the video for the numbering.)
- 2
The See Clearly Method’s advocates not only acknowledge the fringe status of the program,
they regard that position as a virtue. From the instruction manual you will learn that, “In the
history of medicine, new ideas have often been resisted by those schooled in traditional
methods.” Which fallacy is violated in the quoted sentence? (Refer to the video for the
numbering.)
- 4
4. Explain the three ways that we can not use to distinguish science from
pseudoscience, and the four features that do distinguish science from
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pseudoscience.
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The word "pseudo" means "not genuine", "spurious" or "sham", that is
fake - so pseudoscience isn't actual science, although it may appear to be, it's fake
science.
Pseudoscience often uses the fallacious methods we discussed last video in an
attempt to establish credibility when there is little to none present.
a. Whether it’s hard or soft science
- Occasionally you might hear arrogant people state that pseudoscience is soft
science, which is totally wrong
- Hard science refers to the fields of physical, chemical and biological sciences,
whereas the so-called, soft sciences involve fields engaged in the study of human
behaviour like sociology, anthropology, psychology, political science, just to name a
few.
- Both soft and hard sciences aim at explaining phenomena of the natural world
whether that's the behaviour of light, space-time, matter or living organisms, including
people.
- All fields use the rigorous methods for observing, explaining and testing we have
encountered in this module, and so none of these particular fields deserve the label
pseudoscience.
b. Whether the explanations exists within a hard or soft science
- For example, just because something is in the field of astronomy, doesn't
automatically mean that it's science.
- This is because nonsense can be promoted in any subject area.
- Our textbook gives an example of Immanuel Velikovsky who in the 1950s
hypothesized that the planet Venus was created out of an enormous volcanic
eruption on Jupiter.
- He speculated that during its voyage from Jupiter to is current orbit, as it passed by
the Earth, it caused several cataclysmic events.
- Of course, there is zero evidence to support such rubbish, but even the hypothesis
itself is in direct violation of well-established science making it literally impossible to
have occurred.
- Nevertheless, this nonsensical hypothesis lies within the broad area of astronomy, so
a claim or hypothesis being within a respected scientific discipline doesn't
automatically make it science.
c. Whether the explanation was ultimately wrong
- We heard from Prof Lee on the subject of Phlogiston Theory, which became an
obsolete theory after Lavoisier's work.
- Now Lavoisier was one of those scientists that then established a new theory in its
place, "Caloric Theory" (and this is where the word calorie comes from), but that also
ended up becoming obsolete.
- Both of these obsolete theories were considered "well-establish" theories for their
time with various scientific evidence in support of them, having been subjected to the
all the rigours of the scientific method.
- The fact that these theories ultimately ended up being wrong, doesn't make them a
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pseudoscience.
Where science differs from pseudoscience
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Firstly, we see that genuine science is self-correcting, whereas pseudoscience isn't.
This means that when evidence comes to light in science indicating a current
explanation requires revision, pseudoscience simply ignores it.
Because of this pseudoscience rarely develops and matures producing a coherent
theory.
Whereas a scientific discipline continues to develop and change, due to its selfcorrecting nature, gradually producing a maturing body of explanatory and/or
theoretical findings. A pseudoscience produces very little theory.
Of course, as part and parcel of any scientific inquiry, the findings both theoretical
and otherwise are always open to revision, as new evidence comes to light.
This is how a scientific discipline develops. However, in pseudoscience it is quite rare
for the claims, assertions, or speculations to change much as time goes by.
Now the reason, of course, for this continual revision taking place in science is
because science embraces skepticism.
Remember the motto of the Royal Society? Nullius in verba. Skepticism is ever
present in science, which is why the testing part of the scientific method in a nutshell
is required.
However, in pseudoscience, rather than embracing skepticism of the claims, the
claimants tend to view skepticism as narrow-mindedness. Which, of course, isn't a
valid argument not to test an explanation, nor to provide proper scientific evidence in
support of it.
As an aside here, you should be aware that anecdotal evidence, or testimonials, or
eye witness accounts, carries little to zero weight in science.
Examples of pseudoscience
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First up we have, Astrology which is a pseudoscience, and I've mentioned that in the
last video and elsewhere. Note that this area isn't the same as Astronomy.
Ufology, which we encountered in the baloney toolkit video. This isn't the same as the
SETI program, which is solid science devoted to the search for extra-terrestrial life.
Parapsychology is another pseudoscience. Note that this is NOT psychology.
Now within parapsychology we have ESP, which we've mentioned a few times
already. There's also telekinesis and clairvoyance within this domain, but there's a
whole bunch of other stuff that comes under this pseudoscientific area.
Next, we have, of course, Immanuel Velikocsky's work, who was also has engaged in
pseudohistory.
And finally, I've listed cryptozoology, which involves the study of the existence of Big
Foot, the Loch Ness Monster and even the Bukit Timah Monkey Man, which was
mentioned in Workshop 1.
Of course, just because something at present is a pseudoscience, for example
parapsychology, doesn’t necessarily mean that at some point in the future hard
evidence may come to light that indicates otherwise.
If this ever happened, then it would most certainly be a very exciting time as the
scientific community gears up to fully understand the newly reported results.
However, at present these pseudosciences remain at the fringe and carry very little
credibility with the scientific community at large.
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