HSI NOTES by yu xuan :)
Block 1
Lecture 1
1.1 Describe what is science and explain the scientific method “in a nutshell”, illustrating your
explanation with a straightforward example.
- Science is the 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 the scientific
method.
- The scientific method: Observe, explain, test the explanation
- Straightforward example: Troubleshooting a laptop
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Important example: Semmelweis and Childbed Fever (Dr. Ignaz Semmelweis in Vienna
General Hospital from 1846-1849 when germs were not discovered yet)
Observation
1. The mortality rate of mothers due to childbed fever in a clinic
attended by doctors, was, on average, five times higher than
what appears to be a similar clinic with similar mothers but
attended by midwives. (comparative observation)
2. Dr Semmelweis’ friend died after being accidentally pricked by
a scalpel being used by a student doctor while he was
assisting in performing an autopsy and the symptoms and
signs were identical as the mothers who died of childbed fever.
3. After the students attended the anatomical pathology lab,
where they dissected badly infected corpses, they would go to
the maternity clinic to assist in the births of expectant mothers.
Explain
Invisible cadaver matter was picked up by student doctors touching
corpses while working in the anatomical pathology lab. They
transferred it to the mothers giving birth through the usual wounds
suffered during such a process.
Test the
Introduce a policy of using a solution of chlorinated lime for washing
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observation
hands between autopsy work and the examination of patients and
observe the mortality rate in his clinic (which dropped remarkably).
1.2 Describe the roles scientific observations play in the scientific method.
- To identify and focus in on the relevant facts about the phenomena under investigation.
- Provide clues as to what might explain the phenomena - important if the phenomenon
being investigated is really mysterious
- Provide the evidence by which we can determine whether various explanations succeed
or fail
1.3 Explain what are the main concerns that should be addressed when making scientific
observations.
- 5 main concerns:
1. Do we have a clear sense of what the relevant phenomena are?
2. Have we found a way to ensure we have not overlooked anything in the process
of making our observations?
3. Do we know for sure what is based on fact and what on conjecture or
assumption?
4. Have our observations been contaminated by expectation of beliefs?
5. Have we considered any necessary comparative information?
- Galileo’s key observation and realisation (addressed first 4 concerns)
● He was able to ignore the reigning Aristotelian world view and look more closely
at the behaviour of objects slowing and coming to rest.
● His keen eye and intellect were not contaminated by expectation or the belief in
the Aristotelian world view (that all objects when given a push will come to rest
because coming to rest is the nature of solid objects).
● He realised that an object’s nature being supposedly stationary was pure
conjecture, a belief and not a fact.
● Enabled him to notice what others completely overlooked: depending on the type
of contact an object made with a surface it could move more, or less, further.
● Fundamental law of nature discovered: any object, if given a push, will continue
moving forever with the same speed unless something acts to slow it down, like a
hillside, or the slowing-down contact it is making with the surface, the worse the
contact, the greater the slowing down
● Galileo was able to do this because he (1) had a very clear sense of what the
relevant and irrelevant phenomena were (2) he didn’t overlook anything when
carefully observing how objects moved on a surface (3) He knew all too well what
was based on fact and conjecture in the Aristotelian view of how objects moved,
and made sure his observations were (4) not contaminated by expectation or
belief.
1.4 Explain why anomalous phenomena are important for science, illustrating your explanation
with some examples from the scientific revolution.
- An anomaly is something or some state of affairs that can’t be explained with the current
understanding of nature
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Anomalous phenomena provide a way of testing the limits of our current understanding
of how nature works
They can suggest new and fruitful areas for scientific investigation
Can lead to entire new fields of scientific study
1.5 In the context of the scientific revolution, discuss the difference between an evidence-based
understanding of the natural world versus one based on authority.
- Earlier scientists also used the scientific method, like Ibn al-Haytham (1000A.D.)
- Nicolaus Copernicus → did not make any observations!!!
● Published an astronomy book on how the planets orbited the Sun and not the
Earth, and that the Earth itself rotated → directly opposes the accepted idea that
the Earth was the centre of the universe, and that everything rotated about the
Earth
● “Accepted idea” - state religion of the time simply said so, were an authority and
arguing with them is a crime
● Copernicus believed(assumption!!!), as Ptolemy did, that the planets and moon
must move in perfect circular orbits with uniform speed → step in the correct
direction although Copernicus’s newer and simpler system was not any better at
predicting where the planets would be than the Ptolemy system
- Galileo Galilei
● Built powerful telescopes possessing a magnification of 30 times to test
Copernicus’ suggestion as well as the Aristotelian view
● Anomalous phenomena observed: (1) moon was bumpy and cratered (2) there
were moving sunspots on the sun so the sun was not a perfectly clean sphere
and rotates (3) 4 moons orbiting around Jupiter
● Realised that the Sun was the centre of the universe not the Earth (saw all
phases of Venus which proved it orbited the Sun, not possible if the Earth is the
centre)
- Johannes Kepler
● Came up with the idea of the planets orbiting about the Sun in ellipses, rather
than circles (produced the most accurate predictions up till that time period)
- Bacon (most relevant to BDTK)
● 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
- Isaac Newton (end of scientific revolution)
● Presented 3 laws of motion, which were figured out by observations and
experimentations on how objects moved on Earth
● Presented the law of universal gravitation which described how all objects with
mass attracted each other
1.6 Discuss the steam engine’s contribution to the individual revolution and its impact on popular
growth in industrialised nations.
- The industrial revolution is when great technological innovation changed the world where we transited as a species from relying on muscle power to get things done, to
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machines doing the work → set us on a course towards overpopulation, climate change
and biodiversity loss
Industrial revolution 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 → occurred around the late 1700s up until about the early 1800s for
Europe and Northern America
Roles of steam engine:
● Steam engine powered machines could be used to manufacture items in far
greater numbers than people could without them (effective & efficient)
● Iron production was greatly enhanced (steam engine blast air into furnace)
● Machines used steam to product power → to make steam need to heat water →
to heat water need an effective fuel, coal → started our reliance on fossil fuels →
with increase in demand, mines need to go deeper → improved effectiveness of
mining operations
● Steam engine powered trains and ships invented, increasing the efficiency of
moving materials around (including coal and food in great demand)
● Improvements to agriculture, just prior to industrial revolution, coupled with new
machinery now available to assist in farming and effective means of getting it to
where it was needed reduced famine across Western Europe
● City populations increased rapidly, average income increased, SOL increased
consistently → conditions in the extremely crowded cities became bad →
pollution from coal burning, throwing of human waste into the streets, nonexistent
hygiene, many diseases spreading rapidly (tuberculosis was the most deadly)
Why there was substantial drop in mortality rate of population even with bad living
conditions:
● Improvements in agriculture allowing more food to be produced
● Improvements in distributing that food, reducing the likelihood of food shortages
● Improvements in sanitation with sewage systems put in place in cities
Surge in world population takes us into climate crisis and loss of biodiversity at rates
usually only associated with extinction level events
Lecture 2
2.1 Explain the 3 things you should do before applying the baloney detection toolkit (BDTK).
- Possess a skeptical mindset (if we have an explanation that is falsifiable then we have a
scientific explanation, a scientist is ideally someone who is not so easily convinced, but
when there’s solid evidence to support something then it becomes accepted)
- Be aware of your own biases
● Confirmation bias: tendency to seek out information that supports something you
already believe, a particularly pernicious(harmful) subset of cognitive bias e.g.
people who believe 13 is an unlucky number might only keep count of and
remember all of the unpleasant events associated with the number 13
● Availability Bias/Heuristic: tendency to use the information we can quickly recall
when evaluating a topic of idea, even if this information is not the best
representation of the topic/idea e.g. during the pandemic, a doctor asked a
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patient who has fever to test for covid-19 and sent her home when it was
negative, but with time, the symptoms appeared to be increasingly similar to
dengue fever → be aware of the bias itself, make decisions after carefully
deliberating on the matter, do research if the decision really matters, make
important decisions with a team
● Illusory truth bias: tendency to believe false information to be correct after
repeated exposure e.g. many of us were told that the great wall of china is the
only human-made structure visible from space but this is not true
Guard your buttons (make sure your own emotions don’t get the better of you and
override your own critical thinking faculties/cloud your judgement)
2.2 List the tools in the BDTK and explain how they should assist in fact-checking.
1. How reliable is the source of the claim?
● Find out who is the source of this information → look at the authors professional
background
● Use lateral reading to check what other reliable sources say about the source
you are considering
● A well respected, peer reviewed journal with authors from respectable
universities is reliable but be sure to check what other scientists say about their
work
2. What’s the source’s perspective?
● What is their POV? Why was this information shared with you? What is the
purpose of the information you are looking at?
● Funding of the source: could be conflict of interest involved (e.g.might be an
advertisement to try and sell something) which raises a red flag to further
investigate
3. Is the claimant providing positive evidence?
● Evidence must support the claim (must be scientific! does not include
testimonials, eyewitness accounts, sworn statements or signed affidavits)
● Evidence must be reliable (not falsified, misrepresented or fabricated) → lateral
reading to check if the evidence originates from a reliable source
● Evidence must be relevant (must support the claim or argument)
● Data as evidence should be reliable and not misrepresented (is the data
presented honestly and fairly?)
● Claims need positive evidence that directly supports them, not negative evidence
against alternative explanations → absence of evidence isn’t evidence of
absence!
4. Where does most of the evidence point?
● Generally, the explanation where the majority of evidence points, is the one that
is most often correct
5. Have the claims been verified by somebody else?
● Research findings need to be reproduced by others (fundamental to science)
6. Does the claimant use flawed reasoning?
● Does what they say actually make sense? Is there a flaw in the logic?
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Often when people use numbers to try and present their case, they mask the
truth by not properly accounting for an appropriate rate, which invalidates their
argument
2.3 Perform a reverse image search, critically reviewing its results.
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 past the URL you copied into the search bar
2.4 Apply the tools of the BDTK in an online investigation concerning human population growth
over time. (how many children will be born & fertility rate most uncertain)
- Using BDTK on gapreminder.org:
● Tool 1: The site seems reliable and used for school teaching purposes
● Tool 2: Considered the perspective of the site and co-founder, Prof Rosling
● Tool 3-5: Fact checked and referred to various sources such as Our World in
Data and Wikipedia (although a little higher than other sources)
● Tool 6: Carefully thought about how the world population data was visualised and
fact checked his evidence regarding the reliability of the population projections
● Overall: reliable!
Lecture 3
3.1 Describe a scientific explanation and discuss the 2 basic ways in which a theory differs from
a hypothesis.
- Scientific explanation must be testable or falsifiable(able to prove wrong!)
- From mid term paper: cannot always have an explanation for every
observation/anomaly, need to have some observations that the theory cannot explain
- Falsifiability → Has anyone tried to disprove the claim? Is the claimant playing by the
rules of science?
Hypotheses
Theories
Is tentative/unproven, yet subjected to any
testing or falsification
Characterised by the breadth and depth of its
explanatory power, often contain
experimentally well-tested, well confirmed
rules and principles
Limited range of phenomena
Capable of explaining a wide variety of
phenomena
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Types of theories:
● Well-established theories: have been tested numerous times in many ways and
continue to pass all the tests (e.g. Newton’s 3 laws of motion, law of gravitation,
germ theory)
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Obsolete/superseded theories: theories thought to be correct at the time, but
eventually came undone because of new evidence that proved them wrong (e.g.
Aristotelian world view, Miasmatic theory, demonic theory)
Novel/newly proposed theories: can not only explain phenomena already
explained by well-established theories but also explain, or hope to, anomalies
that the current theory has a hard time supporting (currently under investigation)
3.2 Explain the difference between 2 events being correlated and being related as cause and
effect.
- Causal explanations may not be straightforward/simple because:
● A combination of causes leading to an effect
● Cause and effect can refer to groups rather than individual facts/events
● More than one cause can result in a specific effect
● An effect might not result from a given cause in every case (e.g. not everyone
who smokes contract lung cancer)
● Causal explanations can be negative (e.g. wearing a mask helps prevent
covid-19 transmission)
● Causal explanations can involve a series of linked causes and effects (e.g. A
causing B which in turns causes C → A is a proximate cause of B, B is a
proximate cause of C, A is a remote cause of C)
- Correlation (degree which 2 properties, traits or characteristics move in coordination, or
in sync, with one another):
● Perfect correlation: direct 1:1 correspondence between changes in the 2
properties, all the points are on the line (e.g. age of tree in years is perfectly
correlated with the number of rings in the tree’s trunk)
● Positive correlation: when y increases, x increases/when y decreases, x
decreases
● Negative correlation: when y increases, x decreases/when y decreases, x
increases
● Strong correlation: when data points are scattered near the linear line
● Weak correlation: when data points are significantly scattered away from the line
● No significant correlation: no significant relationship between 2 properties
- Just because 2 things are correlated doesn’t mean there is causal relationship
- From mid-term paper: if there are 2 observations that support each other (increase in A
causes decrease in B, increase in B causes decrease in B) → causation
3.3 Discuss the basic features of the following types of scientific explanations: (a) cause and
effect, (b) causal mechanism, (c) underlying process, (d) laws, (e) function.
- Explanatory strategies can be interrelated!
- Other 4 strategies enhance a cause-and-effect type explanation → helps with how one
causes the other
1. Causal mechanism
● Linked chain of causes, taking us from the remote cause, through a series of
proximate causes, eventually leading to the effect we are explaining
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Enhances our understanding of the phenomenon and may even provide us with a
means of reducing the effect if it is bad, enhancing if it is good, or protecting it if
the effect is important and must be maintained, etc.
2. Underlying process (no causes involved in explanation!)
● Describe the observed phenomenon in terms of a more fundamental process
3. Laws
● Generalised descriptions of regularities that have been found to occur in nature
● Tend to be thought of as universal
● “Statistical in nature” → don’t expect it to be obeyed in every case, but there is a
tendency for it to occur more often than not (can be used to explain human
behaviour such as law of reciprocity where when someone does something nice
to you, you will have a deep-rooted psychological urge to do something nice in
return)
4. Function (best explanation)
● Explain something based on the purpose it fulfils
● E.g. Why might someone be eating porridge → not feeling well?
3.4 Explain Occam’s Razor, illustrating its use with an example.
- Choose the explanation that is the least complex and/or most plausible
- From mid-term: when choosing, see if the explanation can be further simplified
- E.g. Copernicus came up with a model of the known solar system that was at that time
much simpler than the currently accepted one by Ptolemy → Applying Occam’s Razor,
we could focus our efforts trying to test the Copernicus’ model, which Galileo did
3.5 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.
- A scientific model is a cut-down and simplified representation of real-world objects,
systems or events
1. Physical models
● Actual physical objects representing some aspect of nature e.g. a globe - a
model of planet Earth
● Help analyse and study the real system they are meant to represent
● Can be augmented with instruments to make measurements of what's happening
in and around the model to assist in better understanding reality e.g. physical
model of an aeroplane can be placed inside a wind tunnel
2. Conceptual models
● Cut down versions of reality with only the parts of interest included e.g. a map
● Diagrams and figures representing ideas and concepts in science e.g. lewis
structures
● Might appear quite similar to real world objects, but could also be diagrams
illustrating processes, even one as abstract as a circuit diagram
● Can be used to explain phenomena and make predictions in the real world
3. Mathematical/Computer models
● When maths can be used to describe nature in some ways e.g. pV = nRT
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● Equations and data are taken together to constitute a mathematical model
Predictions vs projections:
● Projections utilise “what if” scenarios
● Predictions use current data to predict the future
Models vs theories:
● Models can be created from the concepts and principles provided in a
theory/hypothesis → the model can make a prediction of what should happen if a
hypothesis is correct → a subordinate to higher-level theory
● E.g. Newton’s statement of the 3 laws of motion and the law of gravitation can be
used to construct a computer model of our entire solar system → specific
concrete application of the higher-level theory
Lecture 4
4.1 Describe the basic process of experimentally testing a scientific explanation and explain the
importance of eliminating false confirmation and rejection from an experimental test
(A) - Observe
(B) & (G) - Explain
(C) , (D), (E), (F), (H), (I) - Test
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False confirmation: the experiment 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 it in fact doesn’t e.g. polywater (hypothesised polymerized form of
water but has the same properties as sweat, showed that even a slight contamination of
water could produce false confirmation)
False rejection: falsely rejecting the hypothesis that is correct due to improperly designed
experiments
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4.2 Discuss how contemporary scientific research is conducted and its relationship to testing
explanations.
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Hypothesis: speculative or tentative specific explanation that must be falsifiable and/or
testable
Test with experiment: carefully designing an experiment, usually requires research
funding (grants from government or private sector)
Analyse data: the “testing” step in our nutshell version of the scientific method,
sometimes data is measurements from instruments, surveys, images etc. that require
careful analysis
“Getting published” requires review of the work by world experts → having the work
studied and checked by all will further validate, or disprove, the work
2 leading scientific journals → Science or Nature → editors who are world experts in
particular areas of science
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4.3 Explain the meaning of accuracy, trueness, precision and uncertainty illustrating your
explanation with examples.
- Precision: the tightness of the grouping, or how close together different measurements
are to each other (with higher precision, it is much easier to figure out what value
another measurement would be)
- Uncertainty: spread of our readings (high precision means less randomness which
produces small uncertainty), often indicated after the reading with a “±” e.g.
measurement of length 10.3cm, with an uncertainty of 0.1cm will be reported as 10.3 ±
0.1cm. → quantitative measure of precision
- Common definition of accuracy: how close all the measurements are from the true value
● The further to the right we move, the more precise our readings
● The further up we go, the closer an average of a large set of readings are to the
true value
● Uncertainty measures the closeness of measurements, not how far away the
average of those measurements are from the true value
● Poor aim/low accuracy is called systematic error in science (accuracy describes
how badly systematic errors contribute to the measurement)
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The ISO definition of accuracy: high precision AND high trueness
● Trueness measures how close the measurements are to the true value using the
average of the measurements
● All the other patterns other than the top right are inaccurate either because the
measurements are untrue - possessing significant systematic error, or imprecise possessing significant uncertainty
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4.4 Explain the relevance of experimental and control groups and the purpose of randomised
controlled double-blind experiments.
- Law of chance: with enough subjects, the experimental and control groups resemble
each other as closely as possible with respect to any and all variables regardless of
whether all the variables have been identified
- Randomised controlled double-blind trial → randomly assign the test subjects into the
experimental/control group, both subject and experimenter do not know whether the
subject is in the experimental/control group
- Blinding the subjects controls for the possibility of suggestibility influencing the outcome
of the trial in any way, double blinding eliminates additional bias creeping into the
outcome of the experiment from both the experimenter and the subjects
- Placebo effect: Test subjects cannot tell the difference between the 2 treatments (e.g.
vaccination and a harmless injection of salt dissolved in water as placebo)
- Salk Field Trial in 1954:
● Polio was an epidemic disease and they wanted to test if the vaccine is effective
● Not so well-controlled trial: children in P2 with parents consent were given the
vaccine and those in P1 and P3 were to be the control (bias as kids whose
parents consented were more likely to come from higher income families →
higher chance of getting polio as they live in more hygienic surroundings)
● Well-controlled trial: no difference made between P1, P2 and P3 kids, only those
with parents consent were used in the study (half were vaccinated, the other half
in control where placebo was given, harmless salt injection), used random
selection and double blinding to eliminate additional bias
4.5 Explain the meaning of the following terms, (a) margin of error, (b) confidence level, (c)
statistically significant, (d) effect size
- Margin of error provides us with a range of possible values for the result of our
experiment, instead of just one value (have this range because randomness plays a role
in the outcome we observe)
- To find margin of error, you need to specify 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
- E.g. We flipped a coin 50 times and found out the coin has a 40% chance of it coming up
on the number side. At 95% confidence level for 50 samples, the margin of error is
±14%, the confidence interval(CI) is 26% to 54%. 95% confidence level tells us that 95%
of all those experiments we did contain the true value within their confidence interval.
- For a specific sample size, as the confidence level increases, the margin of error
increases.
- If you want to keep your confidence level and reduce your margin of error by half, you’d
have to take four times more samples.
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When the percentage is close to 100% or 0%, the margin of error is smaller than that
given in the table as the CI cannot exceed 100% or be less than 0%
To establish a causal link, need to be confident that there is a statistically significant
difference between the experimental and control groups → note if there is a lot of
overlap in the margins of error in the results at a high confidence level (95% or better) →
look at 4.6
Effect size: being statistically significant does not mean that there is a practical
difference → does not mean that the difference is large, important, or has a big effect
4.6 Apply the 3 rules of thumb to decide if a study has established a statistically significant
difference between an experimental and control group.
- If there is no overlap in the CIs, then the difference is statistically significant at the 95%
confidence level
- If the overlap is less than one-third of the range covered by the 2 CIs, then the difference
could be statistically significant. But the greater the overlap, the less confident we are
that the difference is real
- If the overlap is more than one-third of the range covered by the 2 CIs, the difference is
probably not statistically significant
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Range covered by the 2 CIs is 9% to 37%, which is 28%, the overlap is 17% to 29%,
which is 12%. The overlap is more than one-third, so the difference is probably not
statistically significant → does not prove that the treatment works → need much larger
sample to reduce their margins of error
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Block 2
Lecture 5
5.1 Describe the historical development of our understanding as to the nature of the atmosphere
- William Kingdon Clifford: every citizen has an epistemic responsibility to base their
beliefs on sufficient evidence
- Causal mechanism of climate change: the Sun causes the Earth to heat up, then the
Earth causes the atmosphere to heat up, that in turn the atmosphere causes the Earth to
heat up still further. Earth heats up the atmosphere is because of the presence of
greenhouse gases, if we add the the amount of greenhouse gases by burning fossil
fuels, then the atmosphere will be hotter and will heat the Earth still further
- Atmosphere is approximately 78% nitrogen, 21% oxygen and 1% argon, with trace
amounts of other gases most importantly for this subject, carbon dioxide. Water vapour
can also contribute up to 4% of atmospheric composition depending on the location
- The concept that the atmosphere was a single substance as envisioned by early thinkers
such as Empedocles, unravelled to the realisation that the atmosphere is made up of
many gases
- Historical discoveries:
1. Leonardo da Vinci (Italian polymath)
● First person who suggested that the atmosphere might be something
other than the single substance
● Observed that a portion of air is consumed during combustion and
respiration
2. John Mayow (English chemist and physiologist)
● Later also suggested the same thing as da Vinci, both suggested that air
is composed of 2 distinct components, ‘fire-air’ that supports combustion
and life; and ‘foul-air’ that does not
● Showed that fire requires only a part of air that he called spiritus
nitroaereus (aka oxygen)
● Found that placing either a mouse or a lit candle in a closed container
over water caused the water to rise and replace one-fourteenth of the
air’s volume before extinguishing the subjects → surmised that
nitroaereus is consumed in both respiration and combustion
● Note: both are considered to have independently discovered these results
(information travelled slowly)
3. Jan Baptiste van Helmont (Flemish scientist)
● Coined the term gas to describe the vapours given off when burning wood
and called these vapours sylvestre (aka carbon dioxide)
● Further recognised that carbon dioxide was produced in other processes
such as fermentation of wine
● Considered the founder of pneumatic chemistry
4. Joseph Black (Scottish physician)
● Proved that the gas discovered by van Helmont is naturally present in the
atmosphere
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Heated magnesium carbonate and collected the carbon dioxide given off,
which he called fixed air → found that this gas turns limewater milky
● Further identified that carbon dioxide is present in exhaled breath
5. Reverend Stephen Hales
● First person to suggest that the atmosphere may play a role in the growth
of plants
● Noted that “plants very probably draw through their leaves some part of
their nourishment from the air”
6. Jan Ingenhousz (Dutch scientist)
● Recognised that this nourishment is carbon dioxide
5.2 Discuss the discovery of the greenhouse effect and greenhouse gases
1. Jean-Baptiste Joseph Fourier (French mathematician)
● First person to establish that the atmosphere plays a role in controlling the
climate
● Realised that the Earth itself must radiate, at wavelengths we cannot see →
called this radiation, radiant heat, what we now call infra-red radiation
● Calculated the Earth’s temperature to be -18℃ using precise measurements of
this radiant heat, together with the radiation from the Sun
● In 1824, he realised that the atmosphere 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
2. Nils Gustaf Ekholm (Swedish meteorologist)
● Coined the term greenhouse effect in around 1900
3. John Tyndall (Irish physicist)
● Commonly credited with explaining the greenhouse effect
● Published a series of studies on the way a number of gases, including carbon
dioxide, absorb radiation
● Built a ratio spectrophotometer to measure the extent to which IR radiation was
absorbed and emitted by various gases filling its central tube → realised the
importance of water vapour in the absorption of terrestrial radiation
● Carbon dioxide is 90 times more effective at absorbing IR radiation than air,
methane is 403 times more effective and water vapour is 16,000 times more
effective
4. Eunice Newton Foote (American scientist)
● She identified carbon dioxide as a greenhouse gas a few years before Tyndall,
and noted its important in controlling the Earth’s surface temperature
● Her contribution to science of climate change needs to be more widely
acknowledged given how marginalised female scientists are
● Speculated the concentrations of carbon dioxide could influence global temp
- Underlying process: greenhouse effect is due to the absorption of terrestrial IR radiation
by gases in the atmosphere, primarily water vapour and carbon dioxide
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5.3 Recount the discovery of oxygen and its importance in the emergence of chemistry as a
distinct science
- Johann Joachim Becher (German alchemist), Georg Ernst Stahl (German chemist)
● Established the phlogiston theory for combustion
● Phlogiston theory stated that all combustible materials were made of 2 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 (early
description of biogeochemical cycle)
● Air had no role in phlogiston theory! → led to failure of realising oxygen was a
chemical element
- Discoveries of oxygen:
1. Michael Sendivogius (Polish alchemist)
● Described a substance contained in air which he called cibus vitae or
‘food of life’
● Recognised that this substance is the same gas released when saltpetre
(aka potassium nitrate) is heated
2. Cornelis Jacobszoon Drebbel (secretive Dutch engineer and scientist)
● Performed similar experiments, possibly after a lesson from Sendivogius
himself, purified what he called the ‘spiritous part of it that makes it fit for
respiration’
● Demonstrated to King James I, that his ‘liquor’, presumably oxygen, could
sustain up to 12 men in a submarine for 1-3 hours (first navigable
submarine)
3. Carl Wilhelm Scheele (Swedish pharmacist)
● Manuscript Chemical Treatise on Air and Fire
● Produced oxygen by heating mercury oxide and various nitrates in
experiments, called this gas ‘fire-air’
4. Joseph Priestley (English theologian)
● Most frequently associated with the discovery of oxygen
● Conducted an experiment in which he focused sunlight on mercury oxide
in a glass tube which liberated a gas he called ‘dephlogisticated air’,
because it supported combustion and was totally consumed
● Noted that candles burn brighter in this gas and mice were more active
and lived longer breathing this gas → published in An Account of Further
Discoveries in Air (first to publish)
● Discovered solubility of carbon dioxide varies with pressure and
carbonation, calls his fizzy drink ‘windy water’
5. Antione-Laurent Lavoisier (French chemist)
● Most frequently given a right to the claim of discover of oxygen
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●
-
Had referenced from Priestley and Scheele but claimed to have
discovered oxygen independently
● Was the first person to understand the importance of this gas and was
responsible for naming this gas ‘oxygen’
● Stated that combustion is always and only to do with oxygen, which
combines with other substances during combustion
● Lavoisier, with his wife Marie-Anne, mathematician Pierre-Simon de
Laplace, and using information from Priestley, Scheele and others, who
determined that the burning of coal used oxygen to produce energy and
carbon dioxide
● Lavoisier and Laplace proved that animal respiration is a slow form of
combustion with the consumption of oxygen and release of carbon
dioxide
● Established the Law of Conservation of Mass: the weight gained by a
substance in combustion is lost by the air (defied explanation in the
phlogiston theory)
● Study of gases and solving the problem of combustion is linked
inextricably to the emergence of chemistry as a distinct and rational
science
Applying Occam’s razor, we should give priority to Sendivogius who isolated oxygen first
and correctly associated it with that part of the atmosphere required for life
5.4 Explain the greenhouse effect by reference to the absorption of radiation by greenhouse
gases (water vapour contributes most to greenhouse effect!!!)
1. Arvid Hogbom (Swedish geologist)
● Began attempting to quantify the natural sources of emissions of carbon dioxide
for the purposes of understanding the global carbon cycle → found that the
estimated carbon production from industrial sources, primarily from the burning of
coal, was comparable to the natural sources
● Presented a paper at a meeting of the Swedish Chemical Society, ignited
discussions on the possibility that changes in carbon dioxide concentration could
change surface temperature
2. Svante August Arrhenius (Swedish chemist)
● Considered the effect of changing amounts of carbon dioxide in the atmosphere
● Used a mathematical model to estimate that doubling of atmospheric carbon
dioxide would raise average global temperatures by 5-6℃
● First to conclude that such emissions would lead to global warming, but expected
the warming would take thousands of years
● Suggested that such warming would be beneficial to humanity
3. Guy Stewart Callendar (English engineer and inventor)
● First to demonstrate that Earth’s surface temperature had increased over the
previous 50 years and argued that this temperature would increase due to rising
carbon dioxide concentrations
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●
Theory linking rising atmospheric carbon dioxide concentrations to global
temperature is sometimes referred to as Callendar effect
● Thought this warming would be beneficial, delaying a “return of deadly glaciers”
4. Charles David Keeling (American scientist)
● Produced data showing that carbon dioxide levels were rising steadily in what
later became known as the Keeling Curve
● Famous for his carbon dioxide samples collected from the Mauna Loa
Observatory in Hawaii with funding from National Science Foundation
5. James Hansen (American scientist)
● Told the congressional committee that it was 99% certain that the warming trend
was caused by a build-up of carbon dioxide and other artificial gases in the
atmosphere → recognised that climate change was happening and it was human
caused
- Greenhouse effect ≠ Global warming
- Greenhouse effect is necessary for the Earth to be liveable, 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
- Common metaphor for greenhouse effect is that the atmosphere acts like a blanket, but
is different → blankets keep us warm because they suppress convection, atmosphere
enables convection, metaphor works because more blankets means warmer person;
more greenhouse gases means warmer planet
- Other emissions to the atmosphere that do not follow this metaphor: increasing
emissions of sulphate aerosols will cause the planet to cool not warm
Surface of Earth is warmer than it would be in the absence of an atmosphere, because it
receives energy from 2 sources: the Sun and the atmosphere
5.5 Estimate the greenhouse effect using the single-layer atmosphere model
- Magnitude of the greenhouse effect: difference in temperature between an Earth system
in which gases in the atmosphere absorb and emit radiation, especially in the IR
radiation, and an Earth system which gases let radiation pass unhindered
1. How to find the temperature of Earth in absence of an atmosphere?
- Assume that the Earth emits radiation characteristic of a black body of
temperature T_E (absorbs all radiation)
- Energy impacting the Earth every second: (solar constant×cross-sectional area
of Earth)
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Energy emitted per unit area: (Stefan-Boltzmann constant×fourth power of T)
-
Equating these terms:
-
Earth’s surface temperature would be 279K/6℃
-
Improving the model:
● Assumed that the Earth behaves as a black body (absorbs all the solar
radiation incident), but only 70% is absorbed and acts to heat the Earth
while the rest is reflected
● Find that the temperature is 255K/-18℃ (temperature calculated by
Fourier)
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2. How can we modify our mathematical model to account for the effect of an atmosphere?
Can we calculate the magnitude of the greenhouse effect?
- Wien’s law describes that the wavelength of peak of the spectral distribution is
inversely proportional to its temperature
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Second panel shows that the atmosphere can absorb at certain wavelengths
Bottom panels show that water vapour is the most important absorber particularly
at the longer wavelengths in the infra red and shows that the atmosphere cannot
absorb and radiate at all wavelengths → cannot be treated as a black body!
At visible wavelengths, the atmosphere is largely transparent, it lets radiation in
the visible to pass through without being absorbed → absorbed by Earth’s
surface → Earth’s surface will emit radiation at wavelengths dependent on its
temperature
At shorter wavelengths in the UV, the atmosphere is opaque, it absorbs all
radiation at these wavelengths (due to presence of oxygen and ozone in
atmosphere)
At the IR wavelengths, atmosphere far more opaque, some wavelengths in the IR
absorption is not possible because there are no molecules present that can
absorb such wavelengths → atmospheric windows → radiation emitted at
wavelengths in an atmospheric window will escape unhindered to space
Treat the atmosphere as a single layer of uniform temperature
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3. Mathematical model
- Global average solar flux: energy per unit area per unit time, impacting the top of
the atmosphere (amount of radiation coming from the sun)
- Fs is the global average solar flux, Fg is the flux from the ground (emit radiation
from the ground), Fa is from the atmosphere
- Transmittance is the fraction of radiation that is not absorbed, solar transmittance
is Ts, terrestrial (Earth) transmittance is Tg
-
Solving both equations:
● If solar flux increase, the terrestrial flux will increase → Earth’s
temperature higher
● If solar transmittance increase, Earth’s temperature increase
● Decrease transmittance of terrestrial radiation by increasing amount of
greenhouse gas, terrestrial flux increases → Earth’s temperature increase
● If albedo increases, temperature decreases
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4. Estimating the greenhouse effect
- Ts = 0.8 and Tg = 0.1 means 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
- Earth’s surface temperature is 289K/16℃ → 34K warmer than it would be without
an atmosphere → magnitude of greenhouse effect
Lecture 6
6.1 Describe the history of the establishment of the scientific consensus on climate change
including the role played by the IPCC(Intergovernmental Panel on Climate Change)
- Sixth Assessment Report published by IPCC in August 2021 reports that temperatures
have rise by more than 1 degree since the 1850-1900 global average, and describes the
ways in which Earth’s climate has changed due to human activity as “unprecedented” in
the previous hundreds of years, with some changes as now being inevitable and
“irreversible”
- 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. It is dependent on the
expertise of scientists in question and is based on the accumulation and verification of
evidence (it can also shift!)
1. Guy Callendar
● First person to voice out concerns about global warming
● Was convinced by 1938 that nearly all carbon dioxide produced by fossil fuel
combustion had remained in the atmosphere and suggested that the increase in
carbon dioxide may account for the observed slight rise of average temperature
in northern latitudes in the previous 50 years
● Skeptical as there is so much more water vapour than carbon dioxide, so how
can small increases in carbon dioxide have a big effect? (due to them not
absorbing at the same wavelengths, carbon dioxide absorbs IR radiation)
2. Roger Revelle and Hans Suess
● Published an influential paper that recognised the importance of studying the
Callendar effect as well as the inadequacy of current data → pushed for such
measurements to be an integral part of the scientific project for the International
Geophysical Year
3. International Geophysical Year
● 1 July 1957 until end of 1958 → brought together scientists from across the globe
to study many issues of geophysical concern, including climate change
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●
Charles Keeling received the funding, pushed for by Revelle and Suess, to
measure carbon dioxide at Mauna Loa in Hawaii
4. President’s Science Advisory Committee
● Revelle and Keeling were asked to chair this committee
● Published a report, Restoring the Quality of our Environment, warning that by
2000 there will be about 25% more carbon dioxide present than now and will
cause changes in climate
● President Lyndon Johnson reported the scientific consensus from his Science
Advisory Committee (helps to inform public policy)
5. National Academy of Sciences
● Published a report that acknowledged that climate change is caused by man’s
combustion of fossil fuels and changes in land use
- Consensus that burning fossil fuels will lead to climate change, but there was lack of
consensus for when we would see climate change
- Most scientists at that time thought changes would not become detectable until the 21
century
- James Hansen and co-workers in 1988 published a seminal paper that provided the first
estimate of the natural climate variability → an observed rise of 0.4℃ in global average
would give 99% confidence that global warming had been observed → still testified that
global change was “happening now”
- IPCC:
● 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
● First report in 1990: global mean surface air temperature has increased by 0.3 to
0.6℃ over the last 100 years
● Second report in 1995: global warming is continuing and is most likely due to
human activity
● Third report in 2001: scientific consensus was that human-induced climate
change through burning fossil fuels was being identified in the observational
record
- Naomi Oreskes
● First attempt to determine the level of scientific consensus in the published,
peer-reviewed scientific literature in 2004
● 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
6.2 Articulate the difference between weather and climate, and between greenhouse effect and
climate change
- 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 (reflects the short-term conditions of the atmosphere)
- Climate describes the typical weather conditions in an entire religion for a very long time
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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 is the cause, and climate change is the effect
6.3 Outline how proxy methods used in the reconstruction of past temperatures
- Proxy methods: a variable which correlates to the variable of interest is measured, and
then used to infer the value of the variable of interest
1. Dendrochronology
● Width of tree rings used to determine past climate
● Tree rings are wider when conditions favour growth, and narrower when times
are difficult
● Advantage: the ease with which tree rings can be dated
2. Coral rings
● Bands in the coral’s shell can change in thickness with changes in temperature,
water clarity, or nutrient availability
● Interpretation of the record depends on how the 3 factors are related
3. Ice cores (provides high-resolution estimate of climate changes into the deep past)
● Core sample that is typically removed from an ice sheet or high mountain glacier
● Lower layers are older than upper, ice core contains ice formed over a range of
years
● Measure the oxygen isotope, oxygen-18 in water, which is correlated to
temperature → rate of temp increase seen recently is far more rapid than has
been seen in the last 800,000 years
● Vostok Station ice core can reconstruct past temperatures back to 420,000 years
4. Peat cores (from mid-term)
● Peat is a naturally existing sedimentary material, peatlands are the largest
natural terrestrial carbon source, providing a net-cooling effect
6.4 Recognise the difference between public perception of the scientific consensus on climate
change and that of the scientific community
- Gallup environment poll showed that in 1997 only 48% of US public believed that “most
scientists believe that global warming is occurring” → increased to 61% in 2001 and 65%
in 2006, stayed the same in 2008, dropped dramatically to 52% in 2010, is 68% in 2021
- 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 (from 6.1)
6.5 Explain how the scientific consensus on climate change was established
- Number of questions to be answered:
1. Does observational record show that average global temperatures are rising?
2. Is the temperature rise unusual? (in 6.3 ice cores)
3. Are atmospheric greenhouse gas concentrations also increasing?
4. Is the rise in carbon dioxide due to the burning of fossil fuels?
5. Do we understand human-induced climate change?
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-
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-
-
-
-
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Four major keepers of records on global temperature:
1. National Aeronautics and Space Administration (NASA), USA
2. National Oceanic and Atmospheric Administration (NOAA), USA
3. United Kingdom Meteorological Office (UK Met Office)
4. Japan Meteorological Agency (JMA)
NASA record tends to run slightly higher than the Japanese record, while the UK and
NOAA records are usually in the middle
Differences in datasets due to nature of the sources of the data used:
● Japanese group leaves areas without plenty of temperature stations out of their
analysis → analysis covers 85% of globe
● UK makes similar choices → analysis covers 86% of globe
● NOAA uses nearby stations to interpolate temperatures in some areas that lack
stations → analysis covers 93% of globe
● NASA interpolates more aggressively → areas with gaps are interpolated from
the nearest station up to 1,200km away → analysis covers 99% of globe
Why not satellite data?
● Satellite data only goes back to 1979
● Raw satellite data has to go through a far more extensive “adjustment” process
● Satellites do not directly measure temperatures, and are subject to large
systemic biases → correcting these biases not straightforward
Using 1850-1900 period as proxy for pre-industrial temp, Berkeley Earth dataset gives a
temp rise a little in excess of 1.2℃, IPCC 6th Assessment reports 1.1℃ (q1)
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 since the Industrial Revolution is profoundly unprecedented(q3)
Methane concentrations have increased from pre-industrial values of about 600 ppbv to
over 1800 ppbv (three-fold increase). Nitrous oxide concentrations have increased from
some 270 ppbv to 338 ppbv today (q3)
A biogeochemical cycle traces the movement, through the Earth system, of chemicals
that are essential to life. The global carbon cycle describes the movement of carbon
between carbon reservoirs in the Earth system. An imbalance in the exchange fluxes,
entering or leaving a reservoir, will result in a change in the size of the reservoir. Burning
fossil fuels increases the exchange flux of carbon into the atmosphere resulting in an
increase in the atmospheric carbon reservoir. (q4)
Carbon dioxide has increased by almost 50% from around 280 ppmv in 1750 to current
levels of over 415 ppmv
Scientists proved that the increase in carbon dioxide in the atmosphere is due to the
burning of fossil fuels by measuring the atmospheric concentrations of carbon-14.
Carbon-14 is radioactive and decays with a half-life of some 5,730 years. If we know the
amount of carbon-14 as a function of time in the past, we can use measurements of
carbon-14 to date materials → radiocarbon dating (q4)
Hans Suess realised that burning fossil fuels would dilute the amount of carbon-14
present in the atmosphere → fossil fuels are devoid of carbon-14 as they are formed
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from the fossilised remains of animal and plant life that died hundreds of millions of years
ago → any carbon-14 present will have decayed → affect accuracy of radiocarbon
dating
Paul Crutzen coined the term Anthropocene to denote the current period in which
humans have become a dominant force of global environment change (most common
date for the start of Anthropocene is 16 July 1945 when the Trinity atomic bomb test was
conducted)
Scientists achieve understanding of a phenomenon P if they construct an appropriate
model of P on the basis of a theory T. (q5)
Climate science community use physical, chemical, biological theories to build maths
models (model simulations argue it is impossible to reproduce warming in global surface
temperatures without including the increase in greenhouses gases due, in the case of
carbon dioxide, to the burning of fossil fuels) (q5)
CMIP6 consists of simulations from around 100 distinct climate change models produced
across 49 different modelling groups
Lecture 7
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7.1 Explain why and how doubt about climate change permeated both political and public
spheres
- Affirmation of the scientific consensus on human-induced climate change by President
Lyndon Johnson in his special message to the US Congress in 1965
- President George H. W. Bush affirmed this consensus when he signed the United
Nations Framework Convention on Climate Change at the Earth Summit in Rio de
Janeiro in 1992
- President Bush spoke of the need to take concrete action to protect the planet
- Strong disconnection between political rhetoric and commitment to action (some people
believe that they are more knowledgeable if they have a PhD)
- John Sununu, White House Chief of Staff under President Bush:
● PhD from MIT in mechanical engineering but no training in climate science
● Described Hansen’s work as “technical poppycock”
● Believed that the science underlying the link between global warming and the
combustion of fossil fuels was not sufficient to call for government action
● Instructed his appointee to prevent any US commitments to limit on greenhouse
gas emissions during global treaty in 1989
● “How reliable is the source of the claim?”
- James Hansen - testimonial to prove dire consequences of climate change was heavily
edited by the budget office on orders of Sununu to make prospects of climate change
more uncertain and less serious
- Tricks learnt from the tobacco industry were used to foster mistrust in climate science:
● 1950s, tobacco industry launched a strategy that refuted and ridiculed the
science that linked smoking to health issues, including lung cancer
● 1979, Frederick Seitz learnt the tricks of the trade around doubt-mongering, used
it to cast doubt on the science of climate change
● Fred Singer called Environmental Protection Agency’s study about cancer risks
of second-hand smoke “junk science”
● Seitz, Nierenberg, Jastrow, and Singer cast doubt on the science behind many
environmental issues:
1. Chlorofluorocarbons were not responsible for ozone loss in the
stratosphere. Also wrote papers questioning the link between UV-B and
skin melanoma
2. Sulphur dioxide being released by coal-fired power plants was not
responsible for the acid rain that was destroying forests → argued that it
was due to volcanic emissions
3. Global warming was caused by natural variations in solar radiation; that
any warming caused by greenhouse emissions is swamped by natural
climate variations
4. 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
● Singer’s credentials as an environmental physicist to promote opposing view that
there is no convincing evidence that global climate is actually warming
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●
-
Frank Luntz says “should the public come to believe that the scientific issues are
settled, their views about global warming will change accordingly. Therefore, you
need to continue to make the lack of scientific certainty a primary issue in debate,
and defer to scientists and other experts in the field” → what is the source’s
perspective?
● Significant fraction of the public accepts the deniers’ allegations as true, or at
least are confused by them → do not know what to think or whom to trust →
science significantly undermined, eroding public support for the decisive action
needed to avoid the worst effects of global warming
Even after 30 years of reaching scientific consensus, there were no binding targets or
timetables for greenhouse gas emissions reductions
7.2 Discuss the relationship between neoliberal thinking and lack of regulation to support
mitigating climate change
- Neoliberalism: political approach that favours free-market capitalism, deregulation, and
reduction in government spending
- Oreskes and Conway figuring out why and how the doubt permeated into public arena
(Book “Merchant of Doubts)
- Marshall Institute established in 1984 (deniers of climate change, focused on science
and public policy)
● Robert Jastrow (founding director of NASA’s Goddard Institute for Space Studies)
● William Nierenberg (nuclear physicist working on the Manhattan Project, later
took up Directorship of the Scripps Institute of Oceanography)
● Frederick Seitz (17th President of the US National Academy of Sciences, later
President of Rockefeller University)
- Strategic Defense Initiative(Star Wars) as opposed by Carl Sagan and Hans Bethe equal screen time on news
- Marshall Institute was driven by a political agenda to thwart government regulation →
regulation was about a loss of freedom (no limit to how much government can ultimately
control our lives)
7.3 Apply the Baloney Detection Toolkit to articles written about climate change
1. “Climate’s changed before”
● Reliability: Richard Lindzen was the Alfred P. Sloan Professor of Meteorology at
the Massachusetts Institute of Technology. He was also a lead author of
Chapter 7 of the IPCC's Third Assessment Report → credible claimant with
highly valued expertise in climate science
● Source’s perspective: A contrarian, in particular, for his views on climate
change and the issue of second-hand smoke. Has a long-standing relationship
with the Cato Institute founded by the Koch brothers, whose wealth is derived
largely from oil and natural gas, and who have actively sought to limit climate
change legislation → conflict of interest.
● Claimant providing positive evidence?: Relies on the primary literature to tell his
story, quality of the journals cited do vary in quality
28
● Majority of evidence: Current climate change can only be explained by an
excess of CO₂released by human fossil fuel burning
● Verification of claims: Lindzen identifies two papers, one by Lindzen himself
(inherent bias) and the other by David Douglass (co-author is Fred Singer).
One of the papers that cited the paper by David Douglass reached a different
conclusion → “non-climatic biases have been found in [direct temperature
observations from radiosonde and satellite data]” → Lindzen may be selecting
only papers that support his position → cherry picking
● Is there flawed reasoning: Claimant cherry picks articles and does not share
the great deal of concern within the climate science community about the
reliability of direct measurements in the upper troposphere → straw man (when
a claimant misrepresents a position that is more easily argued against) →
disingenuous to suggest that there was no uncertainty in the temperature
measurements in the tropical troposphere → single cause fallacy
2. “It’s the sun”
● Reliability: David Whitehouse has a Ph.D. in astrophysics → cannot be
considered an expert in climate science → claims to be writing as a science
correspondent → his responsibility to faithfully report the science behind the
article published in Nature → yet there are elements that appear to be opinions
that Whitehouse has drawn that are not found in the research paper
● Source’s perspective: Whitehouse holds a position on the Academic Advisory
Council of the contrarian Global Warming Policy Foundation → should have
concerns about whether this selection of stories was the result of
acknowledged importance in the science world or whether it was due to
personal bias to confirm the correspondents' opinions
● Claimant providing positive evidence?: Correspondent is reporting evidence
presented in the work published by Sami Solanki. The article reports that, “Over
the past few hundred years, there has been a steady increase in the numbers
of sunspots, a trend that has accelerated in the past century, just at the time
when the Earth has been getting warmer.” It further states that “changing solar
activity is influencing in some way the global climate causing the world to get
warmer”. The first statement is acknowledging a correlation, but implies a
causation given the context within which it is written. The second statement
explicitly makes the case for causation even if it does not explain how. This is
not how science works. To make a claim of causation you need a theory—an
explanation. These statements are arguing that correlation is causation—this is
the false cause fallacy. There is also evidence that these statements are the
opinion of Whitehead and not that of Solanki. Solanki clearly believes that the
current work is not sufficient to make the statements made in the BBC News
article.
● Majority of evidence: In the last 40 years of global warming, the Sun has shown
a slight cooling trend. The correlation that was evident in 1880-1980 has
29
evaporated. This is stated in the Executive Summaries of the last few IPCC
Reports that articulates the scientific consensus on this issue.
● Verification of claims: The article does not coordinate any other work that
argues for the conclusions made in the article and the conclusion is not
consistent with the scientific consensus
● Is there flawed reasoning: Whitehouse is engaging in some cherry picking
(ignored data from the last 40 years that shows that the correlation present in
the previous century's worth of data is now absent) → research paper was
used to argue for his opinion. Whitehouse does attempt to cover himself by
acknowledging the consensus opinion that the observed temperature rise is
due to rising concentrations of greenhouse gases (but this point is only made in
the penultimate paragraph) → many readers will have taken the statements
made earlier as the conclusion. Whitehouse argues that correlation is
causation. We should note that the single-layer model introduced in Week 5
argues that increased solar output can be a cause for increased surface
temperature. Whitehouse does not refer to this causal mechanism, perhaps
because he knows that the measured changes in solar output can not explain
the magnitude of temperature increases.
3. “The Earth’s cooling”
● Reliability: Henrik Svensmark is a physicist at the Centre for Sun-Climate
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 → considered an expert
● Source’s perspective: Little evidence that Svensmark is a climate change
denier nor that he has disputed the role that greenhouse gases play in global
warming. He is sceptical of the extent to which increases in greenhouse gases
have influenced the observed increases in surface temperatures. However, the
website, Watts Up With That?, is unabashedly climate change sceptical
● Claimant providing positive evidence?: Claimant is stating that “global warming
has stopped and a cooling is beginning”. The article further states that, “No
climate model has predicted a cooling of the Earth – quite the contrary. And this
means that the projections of future climate are unreliable.” The author argues
that the cooling is because the sun is going through a quiescent phase with the
implication that the sun is playing a significant, if not dominant, role in
determining Earth surface temperatures. The author points to his own
published and peer-reviewed research that indicates the importance of cosmic
rays on nucleating cloud droplet formation → positive evidence for his claim
● Majority of evidence: There are many indicators of global warming. Cherry
picking just one indicator and exclaiming that that indicator no longer shows
warming while ignoring all the other indicators that continue to show the trends
consistent with a warming planet is, at best, disingenuous. Note that in the
years since publication(this article was published in 2009), Earth surface
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temperatures have increased while solar activity has continued its slight
decline.
● Verification of claims: Does not point to the research of others and does little to
counter any arguments opposed to his position. There is a claim in the article
that the cooling they identify will “continue through the next 10 to 20 years”.
Looking back on this it is clear that this claim did not withstand the scrutiny of
the following 5 years since publication. From our future viewpoint, we have all
found the claim to be wanting.
● Is there flawed reasoning: In this act of publication, the website is cherry
picking an article that confirms its climate change denial bias. As for the author,
it is a concern when little to no attempt is made to explain why the voluminous
research that counters your position is wrong. The author seems to state that
he is right and everyone else is wrong. He does point to his research as
evidence, but the lack of support for his position in the science community is
telling. The author is engaging in black or white thinking → sets up a false
dichotomy → makes the case that temperature rise is either due to greenhouse
gas emissions or solar activity (wants to make the case that it is mainly due to
solar activity) → argues that there is a causal mechanism for solar activity
leading to changes in surface temperature. He notes that carbon dioxide
concentrations have continued to increase in the decade before publication, but
that temperatures have not. He argues that because solar activity has declined
during this period of declining temperatures it must be solar activity that has the
controlling effect on temperature and not greenhouse gas concentrations. It
ignores other possible sources of temperature decline. It makes the implicit
assumption that the period during which temperature has declined amounts to
a real trend and not internal variability → cherry picking
4. “Animals and plants can adapt”
● Reliability: Hudson Institute does not discuss climate change specifically in its
areas of interest and there are no fellows on staff who are experts in climate
science → not clear who within The Hudson Institute authored the article, but
the article does name Dennis Avery, a Senior Fellow of the institute. It also
names Fred Singer as a source of the claims made.
● Source’s perspective: Both Avery and Singer are avowed climate change
deniers. The article appears to be a puff piece to promote the book
“Unstoppable Global Warming Every 1,500 Years” by Fred Singer and Dennis
Avery. Avery's book being reviewed by the institute of which he is a Fellow →
conflict of interest
● Claimant providing positive evidence?: Claimants do not identify the evidence
upon which they base their claims, but instead claim that the evidence exists
and is published in journals such as Science and Nature.
● Majority of evidence: 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
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geological timescales. There is also research that explains why climate change
causes extinctions
● Verification of claims: Fred Singer states, “The climate cycle has above all been
moderate, and the trees, bears, birds, and humans have quietly adapted.” →
no reputable sources that agreed with this statement. Certainly there is a
wealth of research that shows that animal and plant life is adapting, but that is a
far cry from arguing that animal and plant life is adapting well
● Is there flawed reasoning: There is wholesale misrepresentation of what the
scientific consensus is → straw man argument. They misrepresent the scientific
consensus as the misrepresentation is far easier to counter. For example, they
state that 70% of global warming occurred between 1850 and 1940. This is not
supported by the global temperature record that shows that 70% of global
warming has occurred since 1940. Elsewhere, they suggest that the so-called
Medieval Warm Period was a global phenomenon rather than a regional affair.
This makes it easier for them to argue that current temperature rises will not
lead to widespread extinction because no such extinctions were seen in the
earlier warming.
5. “It’s not us”
● Reliability: Neil Frank is a meteorologist with a Ph.D. in meteorology from
Florida State University and was the Director of the U.S. National Hurricane
Center between 1974 and 1987 → not an expert of climate science
● Source’s perspective: Frank is a climate change sceptic → based on his
religious belief that the Earth and its ecosystems are robust, resilient,
self-regulating, and self-correcting. Change is an anathema to this belief.
● Claimant providing positive evidence?: First, the article claims, without
evidence, that the cause of global warming since 1850 is natural with minimal
contributions from humans. Second, the article states that CO₂ is “not a
pollutant but vital for plant life”. In its second claim, it also argues that the
contribution to global warming from carbon dioxide is minor compared to that of
water. In this, the claimant is arguing, without evidence, that CO₂is good and
any attempts on reducing temperatures should focus on water and not carbon
dioxide. Third, the article claims, without evidence, that “climate models are
grossly over predicting future warming from rising concentrations of carbon
dioxide”. The claimant is not providing positive evidence.
● Majority of evidence: The preponderance of evidence amply supports the
position that not only is global warming happening, but is human caused. Of the
other claims, no one argues that CO₂isn't vital for plant life, however, climate
sceptics use the carbon fertilisation effect to argue that increased carbon
dioxide is a good thing. Scientists, however, have found that in reality climate
change will have a complicated effect on plant growth. Many studies have
identified that the increased temperatures, the reduced moisture content in
soils and water stress in general lead to reduced plant growth despite
increased levels of carbon dioxide.
32
● Verification of claims: The claimant does not provide any citations to support his
assertions.
● Is there flawed reasoning: Article calls the climate scientists that are identifying
the dangers of climate change as being “alarmists”. In the absence of evidence,
this is an ad hominem attack. There is a straw man argument that CO₂ is vital
to plant growth. There is a false equivalence fallacy made in conflating the
difficulty in getting accurate 10-day weather forecasts with predicting global
climate change over the course of a century. There is also the appeal to
inappropriate authority when they identify the thousands of Ph.D.s and the
hundreds of scientists who have signed petitions doubting human caused
climate change.
Fallacy:
1. Cherry picking fallacy → choosing evidence that supports an argument while ignoring
those that are against it → violates “where does majority of evidence point”
2. Straw man fallacy → when a claimant misrepresents a position that is more easily
argued against
3. Single cause fallacy → when a phenomenon is falsely attributed to a single cause,
even though other causes are possible
4. Ad hominem → attacking the person rather than his/her argument
5. False cause fallacy → a cause is incorrectly identified
7.4 Describe both the key indicators of global warming and the human fingerprints of climate
change
33
7.5 Reflect on your susceptibility to cognitive bias so as to better combat climate change denial
Denials:
1. Science denial
● Science of climate change is not settled
● There is no consensus
● Climate change is just part of the natural cycle
2. Economic denial
● Climate change is too expensive to fix both presently and in the future
(self-fulfilling prophecy)
3. Humanitarian denial
● Climate change is good for us
● Longer, warmer summers make farming more productive
● Plants need carbon dioxide so more of it acts as a fertiliser
● Warm winters will lead to fewer deaths
4. Political denial
● Cannot take action because other countries are not taking action
5. Crisis denial
● Should not rush into committing to binding international agreements, given the
uncertainty raised by the previous areas of denial
● Do not see climate change as a crisis
Cognitive biases:
1. Time-discounting bias (economic & crisis denial)
● Most likely to discount the future when the future is uncertain, distant, and when
intergenerational distribution of resources is involved
● Over-discounting the future, more focused on the present
● E.g. climate change is too costly to fix
34
2. Self-serving bias (political denial & science denial)
● Tendency to expect others to do more than we do
● Tend to first determine our preference for a certain outcome on the basis of
self-interest
3. Illusory truth effect (science & humanitarian denial)
● Positive illusions lead us to conclude that energy problems do not exist or are not
severe enough to merit action
● 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
● Illusion of control leads us to believe that scientists will invent new technologies
to solve the problem
Lecture 8
8.1 Summarise how climate models prove their reliability through hindcasting and successful
forecasting (use meteorological theories, chemical theories & biological theories)
- Moving the goalpost → give multiple arguments when one argument fails to be sufficient
- Initial-value models:
● Projections are model-derived estimates of future climates. When a projection is
branded “most likely” it becomes a prediction
● Hindcasting - reproducing past observations
● Important that the model is not tuned to reproduce past observations → would
greatly limit the confidence we could have in any such model for forecasting the
future
● Initial-value models: models of past climate
● Once running, these climate models do not correct themselves using
observations → can reproduce random variations in atmosphere but not
observed changes in Earth surface temperature → need to be forced by natural
and anthropogenic changes
● Natural forcings: incorporating solar variations and volcanic activity
● Anthropogenic forcings: changes in greenhouse gas, sulphate aerosols, and
land-use
- Supercomputers:
● Divide the planet up into grid cells to make the calculations more manageable
● Calculates the average climate of each grid cell
● Topography will be averaged across a whole grid cell in the model → potentially
overlooks the detail of any physical features (mountains, valleys etc.)
● Parameterization solves the problem where small details are neglected in grids
→ being “parameterized” means their values are defined in the computer code
rather than being calculated by the model itself → one of the main sources of
uncertainty in climate models
● Variance in global average temperature from these different models gives us a
sense of the uncertainty in the model calculations
● Important to not rely on only one climate model
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-
-
-
Hindcasting:
● Hindcast calculations give us a great deal of confidence that climate models
understand the climate processes that led to the increase in temperature since
the Industrial Revolution
● Could be argued that this represents an extrapolation beyond the climate states
in which we know, through hindcast comparisons, that climate models perform
well
Paleoclimate models:
● Have attempted to reproduce the proxy temperature records for much earlier
climates, when temperatures were vastly outside the envelope witnessed since
the Industrial Revolution
● Studying paleoclimates gives us the opportunity to better understand the
sensitivity of models, to among other things, changes in greenhouse gases, and
glacial and sea-level histories
● Today’s climate models can accurately reproduce current climate, and have been
able to reproduce changes to the climate that have been observed in recent
years
Past climate model projections (Hansen’s model, 1988):
● Scenario A: exponential greenhouse gas growth (worse case scenario)
● Scenario B: reduced linear rate of growth (most likely)
● Scenario C: rapid decline in emissions around the year 2000 (best case)
● Easiest assessment of quality of these projections is to compare the temperature
trends predicted against that observed
● Comparing against scenario B, projected 0.26℃ is close to the observed 0.19℃,
but scenario B overestimated the observed temperature trend in the forecast
period → slightly overestimated how much atmospheric greenhouse gases would
increase & had a rather high climate sensitivity of about 4.2℃ for a doubling CO2
(needed a climate sensitivity of about 3.4℃)
36
●
●
●
Hansen also produced a map of the projected spatial distribution of the global
surface temperature change in Scenario B for the 2010s (left one)
Actual amount of warming has been less than projected because of high climate
sensitivity (arising due to the far coarser grid)
Hansen’s mode correctly identified the 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
37
8.2 Predict the effect of feedback loops and discuss the impact of feedback loops and discuss
the impact of feedback on model projection uncertainty
- Positive feedback → exacerbates a small disturbance, leads to instability via exponential
growth (e.g. an increase in the number of cattle running will lead to an increase in overall
level of panic in the herd, increasing the number of cattle running → stampede)
- Negative feedback → output of a system is fed back in a manner that reduces the
fluctuation in the output → leads to stability (e.g. increase in blood glucose levels will
lead to an increase in insulin secreted by the pancreas → decrease in blood glucose
level → stable blood glucose level)
- Negative coupling (denoted by circle-headed arrow) → increase in one element leads to
a decrease in a connected element or vice versa
- Positive coupling (denoted by a normal arrow) → increase in one element leads to an
increase in a connected element or vice versa
- Negative feedback loop in Earth system (photosynthesis → decrease in CO2)
-
Positive feedback loop in Earth system
-
Surface temperature and water (for negative feedback loop, increase in albedo
decreases surface temperature, single negative coupling)
-
In general, any feedback loop that includes an odd number of negative coupling will be a
negative feedback loop. A feedback loop that includes 0/even number of negative
coupling will be a positive feedback loop
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-
What would be the global average temperature in an atmosphere with double the
pre-industrial CO2 concentrations?
If we double CO2, the transmittance of terrestrial IR radiation through the atmosphere is
decreased, and less total radiation will leave the atmosphere. In order to bring the
system back into balance, the temperature of the Earth's surface has to increase.
Assume nothing else changes, a doubling of CO2 will lead to an increase of surface
temperature of about 1.25℃.
Increase in surface temp → increase in evaporation rate → increase in amount of water
vapour in atmosphere (greenhouse gas) → further increase in surface temperature →
positive feedback loop will increase the initial temperature rise by further 60%
Increase in surface temp → melting of ice allowing the surface and exposing the
underlying surface → decreases the albedo → positive feedback loop will increase the
initial temperature rise by a further 20%
39
-
Climate sensitivity (net effect of initial warming due to doubling CO2 & the feedbacks in
the Earth system):
Best estimate of climate sensitivity in the Sixth Assessment Report is 3℃ with a likely
range of between 2.5℃ and 4℃
-
Oceans take a long time to heat up → current increase in Earth surface temperature
since the 1850-1900 baseline is about 1.1℃
However, current levels of CO2 in the atmosphere would imply an equilibrium Earth
surface temperature of over 1.7℃
Avoiding such an equilibrium temperature requires us to not only stop adding to the
atmospheric CO2 concentration, but to reduce it
Most of the feedback loops that add to climate sensitivity involve processes that need to
be parameterised → parameterisation is important to estimate uncertainty in models
8.3 Describe and contrast the climate change projections resulting from possible future climate
scenarios
- Emissions scenarios:
● Constructed to explore further developments in the global environment
● Four storylines that highlighted the main scenario characteristics and dynamics,
and the relationships between key driving forces
● The four storylines combine 2 sets of divergent tendencies: one set varying
between strong economic values and strong environmental values, the other set
between increasing globalisation and increasing regionalisation
40
-
-
Representative Concentration Pathways (RCP)
● Described different levels of greenhouse gases and other radiative forcings that
might occur in the future
● Each RCP is labelled with their radiative forcings (change in energy flux in the
atmosphere caused by natural or anthropogenic factors of climate change)
● RCP1.9 is a pathway that limits global warming to below 1.5℃, 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 (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
Shared economic pathways (SSP):
● Describe how socioeconomic factors may change over the century
●
●
SSP1 → describes a world of sustainability-focused growth and equality, narrates
a future in which the world shifts gradually towards a more sustainable path,
emphasising more inclusive development that respects perceived environmental
boundaries
SSP2 → describes a world where trends broadly follow their historical patterns,
narrates a future in which the world follows a path in which social, economic, and
technological trends do not shift markedly from historical patterns
41
●
●
●
●
●
●
●
●
●
SSP3 → describes a fragmented world of resurgent nationalism, 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
SSP4 → describes a world of ever-increasing inequality, 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
SSP5 → describes a world of rapid and unconstrained growth in economic output
and energy use, 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
These narratives describe alternative pathways for future society and 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
SSP1 and SSP5 envision relatively optimistic trends for human development,
with substantial investments in education and health, rapid economic growth, and
well-functioning institutions, but SSP5 → fossil fuel based economy while SSP1
→ sustainable development
SSP3 and SSP4 are more pessimistic 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
SSP1 and SSP4 gives us the best chance to find mitigation solutions
RCP1.9 and RCP2.6 pathways require very stringent mitigation efforts, achieved
by SSP1
Less stringent RCP4.5, RCP7.0 and RCP8.5 pathways have been achieved
under the SSP2, SSP3 and SSP5 narratives respectively
42
●
●
Not all representative concentration pathways can be achieved under all shared
socioeconomic pathways
Ratios in each cell indicate the number of models that succeeded in making the
scenario work out of the total number of models used
43
-
Projected greenhouse gas emissions
44
-
Projections of global average temperature
●
-
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℃ and 2℃ will be exceeded during the 21st century unless
deep reductions in CO2 and other greenhouse gas emissions occur in the
coming decades
Temperature simulation
●
●
●
●
As the simulations progress you can see that the oceans warm more slowly than
land because it takes up much more heat to warm water than land
Middle of continents are expected to warm more than coastal areas, regional
topography will also influence this too
At high latitudes, especially in and near the Artic, 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℃ to 2℃ increase in temperature for the
low greenhouse gas emissions scenario, to between 4℃ to 5℃ increase in
temperature for the very high greenhouse gas emissions scenario
45
-
Precipitation simulation
●
-
Although global average precipitation increases by between 3% to 10%, this
additional precipitation is not distributed evenly around the globe
● Much of the increase in precipitation is expected to occur at high latitudes
● Some places in Antarctica are even gaining more snow via increased
precipitation than they are losing to melting caused by rising temperatures
● Change in precipitation patterns may cause a greater incidence of flooding,
especially in combination with land use changes such as deforestation
● However, many areas, especially in low- and mid-latitude regions, are expected
to suffer from more frequent and more severe droughts → more wildfires
● Disruptive to ecosystem and agricultural systems in disrupted systems
Projections of arctic sea ice
●
Arctic is projected to be practically ice-free near mid-century under intermediate
and high greenhouse gas emissions scenarios
46
-
Projections of ocean surface pH
●
-
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
● Further impact many ocean species like oysters and corals that make hard shells
and skeletons by combining calcium and carbonate from seawater
● Decreasing pH → acidification, if pH gets too low, even shells and skeletons can
dissolve
Projections of sea level
●
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
8.4 Explain how climate change mitigation strategies relate to principles of equity
- Science can inform public policy, but cannot define public policy
- Universal declaration of human rights
● Proclaimed by the UN General Assembly in Paris on 10 December 1948
● “Recognitions 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…”
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-
-
Principles to govern international action
● Precautionary principle: the lack of scientific certainty should not prevent
appropriate action from being taken & should not be used as a reason for
postponing cost-effective measures to prevent environmental degradation
● Polluters should pay for the damage of their pollution: recognises that carbon
dioxide and many other greenhouse gases are global pollutants, they affect
global commons
● Equity (both intergenerational and international): intergenerational equity argues
that we hold the natural environment of our planet in common with all members
of our species → most difficult to apply → the richest half are responsible for 86%
of global CO2 emissions, the bottom half are responsible for only 14% →
UNFCCC recognises this by stating in a clause that the richest half should take
the lead and first action in combating the problem and reducing emissions
Contraction and convergence put forward by the Global Commons Institute
●
●
●
●
Proposes stabilisation of atmospheric CO2 at an agreed level (450 ppmv)
First part of the proposal is that the world as a whole agrees to follow the
envelope curve - ‘contraction’ part
Second part of the proposal is that eventually, from 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 - ‘convergence’ part
Third part allows for trading of emissions → those that have more than they need
can sell to those who want to emit more → move money from developed nations
to developing nations (help developing nations industrialise in sensible ways &
appropriate non-fossil fuel energy systems)
48
-
-
To limit global warming to 2℃ over pre-industrial levels, need to limit the cumulative
amount of CO2 emitted since the beginning of the Industrial Revolution to 1 trillion
tonnes → however, recent projections suggest that a 1.5℃ limit may be required
With our current consumption, we will exceed 1 trillion tonnes by 2045
Emissions Stabilisation Wedges Strategy
●
●
Although no single strategy will suffice, a combination of technological strategies
described here will build the stabilisation required
Further wedges such as behavioural wedges may be needed to reach net zero
carbon emissions
49
8.5 Reflect on how you incorporate new knowledge into your current understanding and on the
danger of absolute uncertainty
-
Be open to test your reality, do not fall to the arrogance of knowing the truth
Recognising that our opinions are fallible, being willing to acknowledge our fallibility, and
to make lasting change to behaviour e.g. eating less meat
Carbon dioxide and stratospheric temperatures have a negative correlation
50
Block 3
Lecture 9
9.1 Green cover in Singapore: from ‘catastrophic extinction’ to some recovery
- Why we need biodiversity:
● Forests absorb carbon dioxide from the atmosphere
● 1.6 million species known but over 7/8 million species in the world, about 6
millions species that we do not know (smaller you go, the more left to find), but
many species could be lost due to intensification of human action
● Source of food (microorganisms that enrich the soil we grow our crops,
pollinators that give us fruits, animal protein), medicine (from plants and fungi),
shelters (trees protect our homes from flooding, coral reefs shield coastlines from
storm surges)
● Ensures the habitability of the planet and sustain economies
- Human action are destroying biodiversity:
● Changes to habitat for grazing, mining and crop production including the use of
harmful fertilisers that affect land and sea species
● Overconsumption leading animal species to extinction
● Climate change - in 2016/2017, half of the corals in great barrier reef died due to
warming of the seas
- What must we do?
● Reduce carbon emissions
● Leave enough space for natural habitat, preserve these hotspots
● Rebuild biodiversity (create protected areas/laws to protect endangered species)
● Hands-on management to allow animals to grow peacefully and restore animal
population
● Create pathways for species to travel
- How singapore’s biodiversity got destroyed through settlement, clearance and
urbanisation:
● 1819 - rapid deforestation with British colonisation
● 1900 - 90% of primaeval forest cleared mainly for agriculture (e.g. pepper,
gambier)
● 1959 - rapid urbanisation & large-scale land reclamation with independence
(‘Garden City’ vision introduced by Lee Kuan Yew was integrated into
Singapore’s national development plan → provide shade and green spaces for
the community)
● 1973 - < 30% land area natural vegetation
● 1990 - >99% of original forest lost, >50% of Singapore is urbanised (catastrophic
loss in biodiversity)
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-
Recovery, restoration and enhancement:
●
●
●
●
By 2011, vegetation cover is 56% but <2% old secondary and primary forest,
27% managed vegetation (parks, gardens, lawns etc), 29% spontaneous
vegetation → singapore has not recovered from ‘catastrophic extinction’ of the
past
Singapore’s most biodiverse forests are located within nature reserves, are our
oldest forests and host to rare animals like the leopard cat
Parks, park connectors (360 km across singapore) and nature reserves → allow
recovery of adaptable wildlife (ecological connectivity for wildlife to move around
and increase viable area for animals) → return of the southern pied hornbill to
mainland Singapore
The forest fragments of nature reserve have increased in size, and are gradually
being enhanced (e.g. protection of Bukit Timah forest fragment with the addition
of buffer parks to increase its size) → nature parks contribute to being buffer
52
parks to nature reserves but will take centuries for the nature reserve to colonise
the area again (especially if they were previously settlements) → important to
help enhance these buffer parks (deliberate planting, seed banks → succession)
●
-
-
-
4 nature reserves → core biodiversity areas containing some of our primary
rainforests and provide home for our native plants and animals → conservation!
Largest native ecosystems in Singapore:
1. Mature secondary forests of Bukit Timah and Central Catchment Nature
Reserves
2. The mangrove forests at Sungei Buloh Nature Park Network and Pulau Ubin
Waterways:
● Rivers used to be anoxic (no oxygen, no living animals) as people tossed their
trash into the waterways
● Now, cleaned rivers for drinking water catchment → 17 reservoirs in Singapore
used to collect and store rainwater and used water
● Single naturalised canal at Bishan-AMK Nature Park → planted up with
vegetation, slopes, return of smooth-coated otters (adaptable urban species)
● Malaysia is the source of otters → Singapore is the sink (about 17 families now)
Coastal and marine environments:
● Coastal reclamation was done excessively in the past
● 2014 → Sister’s Island Marine Park (first marine park)
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● 2018 → Mandai mangroves and mudflat declared a nature reserve
9.2 SGP2030 and the “city in nature” vision → green, livable and sustainable Singapore
- The green plan is a multi-agency effort spearheaded by 5 ministries:
● MOE
● Ministry of National Development
● Ministry of Sustainability and the Environment
● Ministry of Trade and Industry
● Ministry of Transport
- Green plan is couched as a “living document” → more work is being done to refine it and
more targets as being established to strengthen Singapore’s commitments under the
UN’s 2030 Sustainable Development Agenda and Paris Agreement → positioning us to
achieve our long term net zero emissions aspiration by 2050
- Concern about biodiversity issues in Singapore by the nature community:
● Sustainability awareness has increased, but understanding of biodiversity is poor
● Have not prioritised protection and connected sufficient pockets of valuable
young secondary forest
● Advocacy has to be sustained until policy makers and planners understand the
issues
- Pillars in SGP2030:
● Pillar 1: City in Nature (more nature parks, park connectors)
● Pillar 2: Energy Reset
● Pillar 3: Sustainable Living
● Pillar 4: Green Economy
● Pillar 5: Resilient Future
- Pillar 1: City in Nature (by 2030) → land allocated to nature parks double, accessibility to
park is guaranteed
● Conserve and restore natural ecosystems
● Establish world-class gardens and parks with nature
● Restore nature into the urban landscape
● Strength island wide ecological and recreational connectivity
● Enhance veterinary care and animal management
● Build science and technology, and industry capacity
● Inspire communities to co-create and be stewards of nature
9.3 Importance of ecological connectivity in Singapore
- For parks and young forests to be connected with sources of greater biodiversity & for
polling and seed-dispersing wildlife to be able to move between areas of source and sink
- Wildlife are present in our forests and play an ecological role (ecological functions) which
help maintain forest health
- Examples of wildlife : common palm civet (gardener that disperses fruit), greater mouse
deer (seed disperser and prey species), Malayan pangolin (regulates the ant and termite
populations, their digging action helps to aerate the soil), leopard cats (predators of small
mammals)
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-
-
-
Roads result in fragmented forests → threaten wildlife with roadkills, impact genetic
variability and forest resilience (fragmented habitats isolate animal and plant
populations) → larger countries affect more species on larger scale
3 types of wildlife: Urban avoider (confined to natural habitats e.g. leopard cat), urban
adapter (occur at margins or partly naturalised urban areas, occasionally straying into
urban areas e.g. smooth-coated otter, common palm civet), urban exploiter (e.g. exotic
rats)
5 types of wildlife: aerial, arboreal, terrestrial, fossorial, aquatic
9.4 Are all green spaces alike?
- Different shades of green:
● Grasslands → consist mostly grass
● Scrublands → has grass cover and some scrubs
● Woodlands → can find some tree cover, but where the sparse tree canopy is
insufficient for forest species to find shelter and food
● Forests → dominated by trees and other woody vegetation
- Tropical rainforests → main vegetation type native to singapore
- Forests consists of layers of vegetation: understory, sub-canopy, canopy, emergent layer
- Primary rainforests have high species richness (original forest; 10% in 1900; now 0.28%)
- Secondary rainforests have emerged from disused agricultural land
- Mature secondary rainforests (later stage of growth) → mainly within or near our nature
reserves → still have high species richness compared to young secondary rainforests
which are dominated by plants
- Exotic dominated secondary forests → where the land has been cleared completely
before → dominated by highly invasive vegetation which grow and reproduce quickly
9.5 The Ecological Profiling Exercise & The One Million Tree movement
1. Ecological Profiling Exercise (2020)
- Previously, development prioritises maximising development with managed
planting added after
- Now, each development site is evaluated holistically by NParks (whether it is
linked to a source habitat/contributes to a nature corridor)
- NParks identified “source habitats” and nature corridors in Clementi-Ulu Pandan
area
- 2 main ecological connections found between Bukit Timah Nature Reserve and
the Southern Ridges
2. One Million Trees Movement (2020)
- Protect, enhance and connect coastal habitats, to enable resilient terrestrial and
coastal wildlife species to survive and recolonise
- Not sufficient to offset singapore carbon emissions as it exceeded 40 million
tons/year and also requires reductions in power consumption, construction, and
transport sectors, amongst other things
3. NUS’ planting commitment (2018)
- Upgraded to planting 100,000 trees by 2030
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Extra: David Orr’s article
- “it too emphasises theories, not values; abstraction rather than consciousness; neat
answers instead of questions; and technical efficiency over conscience”
- “Forest loss, wildlife extinctions and climate change are outcome of actions by highly
educated people”
- Points he wants to make:
1. Education is no guarantee of decency, prudence or wisdom → the worth of
education must now be measured against the standards of decency and human
survival
2. Goal of education should be to connect intelligence (long-range and aims
towards wholeness) with an emphasis on whole systems and the long range with
cleverness (short-range and tends to break reality into bits and pieces), which
involves being smart about details
- Six myths of higher education:
1. Ignorance is a solvable problem (rather, it is an inescapable part of human
condition)
2. With enough knowledge and technology, we can “manage planet earth” (makes
better sense to reshape ourselves to fit a finite planet than to attempt to reshape
the planet to fit our infinite wants)
3. Knowledge, and by implication human goodness, is increasing (some knowledge
is increasing while other kinds of knowledge are being lost)
4. We can adequately restore that which we have dismantled (we fragmented the
world into disciplines and subdisciplines → most students graduate without any
board, integrated sense of the unity of things)
5. The purpose of education is to give students the means for upward mobility and
success (the planet does not need more successful people → need more
peacemakers, healers, restorers, storytellers, lovers of every kind to make the
world more habitable and humane)
6. America represents the pinnacle of human achievement
- Principles to rethink education:
1. All education is environmental education
2. The goal of education is not mastery of subject matter but mastery of one’s
person
3. Knowledge carries with it the responsibility to see that it is well used in the world
4. We cannot say we know something until we understand the effects of this
knowledge on real people and their communities
5. Need (a) faculty and administrators who provide role models of integrity care, and
thoughtfulness, and (2) institutions capable of embodying ideals wholly and
completely in all of their operations
6. Process is important for learning → the way in which learning occurs is as
important as the content of particular courses
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Lecture 10
10.1 What can we do about ecosystem degradation? Plant a tree, plant a forest!
- One Million Trees movement (2020) → city in nature pillar
● Mostly leave the nurturing of the trees to NParks (usually just plant the tree and
then walk away)
● 505,799 trees planted to date (target: 100,000 per year)
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Why can’t young forests be left to mature naturally?
● Formerly cleared and cultivated land
● No seed bank, so cannot mature
● Will be stuck in current phase for centuries
● Assisted panting is required
● Maintenance of plot until independent (2 years?)
Afforestation at Kranji Coastal Nature Park (collab between NUS Toddycats & NParks
since 2020)
● Mangrove cleanups began in 1997
● The annual trash load gradually declines
● The area is integrated into Sungei Buloh Wetlands Reserve in 2014
● NParks proposes coastal restoration; names site KCNP
Habitat enhancement (more than tree-planting)
● First step: soil preparation + tree planting
● Second step: Sapling Protection Action (make sure they are not suffocated from
the pioneer plants, clear the space around them)
● Soil preparation: weed clearance, soil exposure, soil loosening, soil digging, soil
enhancement, tree hole readiness
● Standard enhancement procedure for the soil by NParks(proof soil mixture, right
combination of minerals and other chemicals)
● Saplings grow slowly under shade, but the grass around them grows really
quickly and there is little shade in the park, if no maintenance, they will die very
quickly as they cannot compete for sunlight
● When saplings become bigger, there is more shade and grass grows slower due
to lesser sunlight exposed to them
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Buffer parks with a history of harsh use, require enhancement to ‘catch up’
25 Jan 2019: NParks Forest Restoration Action Plan for nature areas
10.2 What can we do about ecosystem degradation? Connect forest fragments!
- Help restore connectivity between forest fragments, help improve movement of wildlife
between forest fragments, improve genetic resilience of forest fragments
- Culverts
● Tunnels that go below the road surface
● Animals use these culverts (lesser false vampire bats, malayan porcupines)
- Rope bridges
● Meant for arboreal animals (animals that climb on trees)
● E.g. monkeys, langurs
- Ecolink across the BKE (2013)
● Huge highway for animals (link central catchment and Bukit Timah nature
reserves)
● After Bukit Timah expressway was built in 1986, there were many roadkills
● Common palm civets, pangolin, slow loris use the ecolink
● Animals can find safe passage between nature reserves, expanding their
habitats, genetic pool and chance of survival (ecolink provides food and green
cover for animals crossing it)
● Over 3,000 native plants planted
● Part of singapore's efforts to conserve biodiversity → public not allowed to enter
10.3 How to establish connectivity? Case study from Labrador-Keppel
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Dramatic changes to Singapore’s coastline led to a significant loss of coastal
habitats and their wild communities → all precious, coastal and marine
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Berlayar Creek instead of being curvy as seen in 1914 map, has become
canalised in 1930
● Freshwater swamp has been drained
Berlayar Creek & Labrador Park today
● Marginal habitats have survived and are protected
● Planting has been conducted as part of One Million Trees movement
● Keppel golf course → not permanent → repurposed as a residential estate →
how to link green spaces? Will connectivity be retained? → connect Southern
Ridges to Labrador Park and Keppel Golf Club to promote ecological
connectivity?
● Which animals to link up? What kind of connectivity?
10.4 Are there still challenges?
- Impact of fragmentation and high visitorship at the 164ha Bukit Timah hill
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1985: Scientists raised concerns over BTNR’s health in Sunday Times article
1995: Special edition of Gardens’ Bulletin on BTNR
2002 & 2011: BTNR “patient under intensive care”
2014: NParks announces closure of BTNR for enhancement and improvement
works (slope stabilisation, trail repair, boardwalk, enrichment planting)
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Public demanding was acute (did not understand the science behind the closure)
→ even though science says something, other aspects also have to be
considered (had to given in to public pressure) → after closure of 6 months, the
Summit Trail of BTNR was opened to visitors
What next?
● People will always create impact from the sheer number of visitors
● Impact to wildlife, vegetation and soil is known
● Should we try seasonal opening of routes?
Planning Singapore’s Future
● Need to balance many different needs (manufacturing, housing, nature)
● SIngapore Master Plan 2019 (reviewed every five years) → shows projection of
various land uses for development in Singapore
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Evaluation of projection now involves engagement → investigation done
internally → call stakeholders to come to comment on the report → media will
cover it, public will provide feedback
Constructive consultation → meetings held regularly between developing
agencies (LTA,JTC,HDB,MINDEF and regulators such as NParks and PUB with
the nature community) → ensures better outcomes for biodiversity conservation
and climate change mitigation
“... 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” - Minister Desmond Lee
Youths are involved (global movement) →iIn singapore, Singapore youth voices
for biodiversity(SYVB) → always communicating with NParks
10.5 Human-wildlife coexistence - wildlife responds and so should we
- Presence of 3 types of wildlife (lecture 9.3)
- Tapping the expertise of a dedicated landscape (ground up Working Groups) → NGOs,
researchers, interest groups/individuals
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https://www.ourwildneighbours.sg/ (website with tips to coexist with our wild neighbours)
10.6 Biodiversity conservation requires more than science
- Need community involvement!!!
- As a result of the Convention on Biological Diversity
● NParks announced the National Biodiversity Centre in 2011
● Singapore established National Biodiversity Strategy and Action Plan goals
1. Conserve and enhance biodiversity at the genetic, species and
ecosystem levels
2. Ensure sustainable use of Singapore’s biodiversity resources
3. 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
Lecture 11
11.1 What is the problem?
- Dominant and large plants of the Carboniferous Period (359 - 299 million years ago)
during the late Paleozoic Era (swampy grounds, moist planet)
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How coal was formed:
● Before the dinosaurs, many giant plants died in swamps
● Over millions of years, the plants were buried under water and dirt
● Heat and pressure turned dead plants into coal
● Fossil fuels contain carbon fixed by primary producers millions of years in the
past
Carbon emission sources from accelerated resource extraction since the industrial
revolution (extracting coal from beneath the ground)
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Data of what generates greenhouse gas emissions is useful in strategizing how we want
to mitigate the effects of global warming → set targets
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Global warming of 1.5℃
Disproportionate effect in terms of biodiversity impacts → while emission contributions
might be quite low (2.2% net emissions of carbon dioxide from deforestation) →
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biodiversity loss → flooding, erosion, loss of ecosystems (air,water,food); timber,
medicines, raw materials, fuels etc. → can have a compounding effect
Katherine Hayhoe says: the climate is changing, humans are responsible, the impacts
are serious, the time to act is now
11.2 Inequalities of climate change
- Ecological deficit occurs when the footprint of a population exceeds the biocapacity of
the area available to that population
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The economically advanced countries have far greater consumption and emissions →
far disproportionate compared to the rest of the world → unequal contributions between
countries relative to GDP
A country’s overshoot day is the date on which Earth Overshoot Day would fall if all of
humanity consumed like the people in that country
Thinking about history since the industrial revolution, the more economically advanced
the country is, the greater responsibility it has for the situation now
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Correlation of ecological footprint (2008) and the human development index (2012):
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Socioeconomic status (independent of countries) → not all are consuming equally
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Are we part of a global elite? 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 (like Singapore) are so much more vulnerable to impacts of climate
change e.g. droughts, heat extremes, floods, rising sea levels, tropical cyclones
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The poorest are the ones who experience the impacts of climate change the most and
contribute to the accumulation of greenhouse gases the least→ inherent inequities of
climate change impact
In framing the objective of holding the increase in global average temperature rise to well
below 2℃ above pre-industrial levels, and to pursue efforts to limit warming to 1.5℃, 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 requires a global collective effort that may be guided by the 2015 United Nations
Sustainable Development Goals
11.3 What is 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
- The areas that sustain and support the city
- Where agricultural and farming practices take place, provides its city with resources such
as water, energy, food and clean water
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Singapore has no hinterland → global trade & local production can swap for the lack of
hinterland
11.4 What are we dependent on?
1. Food
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Wide import market with local production to complement global supply
2019 - As a result of climate change and rising population, the world is set to face
a 56% shortfall in food nutrition by 2050
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
SGP2030 target: meet 30% of Singapore’s nutritional needs through locally
produced food
2. Water
● Water is the source of sustainable development and climate change adaptation,
yet only 0.5% of water on Earth is usable and available as freshwater → over the
past 20 years, terrestrial water storage has declined by 1cm per year → 25% of
the population are living in countries under water stress → 3.6 billion people face
inadequate water access per year → water-related hazards (drought/floods) are
increasing → 2021 state of climate services report 6 strategies including the
adoption of more integrated water and climate policies by joining a new Water
and Climate Coalition
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2015 El Nino: Singapore consumes 400 million gallons of water a day, during that
time period, 3 districts in neighbouring Johor underwent water-rationing 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 increase freshwater production to tide us over → few
noticed the water shortage
● Four national taps → water from local catchment, imported water, NEWater,
desalinated water
● Demand for water will only increase with time → but sources will change →
proportion of water supply by NEWater will increase from 40% to 50% in 2030
and up to 55% in 2060
● Through a network of rivers, canals and drains(water catchment areas), rain that
falls on about two thirds of singapore land channels water into our 17 reservoirs
● 58 years after singapore's last water rationing exercise, some might be taking
clean water for granted
● SGP2030 target: reduce household water consumption to 130 litres per capita
per day
● 2025 target: singapore’s first integrated waste and used water treatment facility to
be 100% energy self-sufficient (Tuas Nexus)
3. Energy → highest source of global greenhouse gas emissions
● Renewables begin to enter to provide alternatives as source for energy with
increasing consumption of fossil fuels
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Nudging divestment of fossil fuels towards renewable energy → carbon pricing
slowly increasing → will be raised up to 50-80/tCO2e by 2030
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SGP2030 energy targets:
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11.5 What can we do?
- Since 2018, more than half the world’s population live in cities → major pressure on all
natural land
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Sustainable Development Goals(SDGs) are a set of goals under the 2030 Agenda for
Sustainable Development, which is a global development framework adopted by World
Leaders at the UN Sustainable Development Summit in September 2014 (comprises 17
SDGs with 169 targets and there are currently 247 indicators used to measure progress
towards reaching the targets)
2030 agenda for sustainable development: pick 2 areas most relevant for your country
and are able to tackle → will invest more in those fields as need to report back
Globally, cannot achieve so many goals so more meetings to achieve resolve - COP27
→ political assemblies with many terms to come into terms with → gradually improves
Six key issues at COP27, the 2022 United Nations Climate Change Conference →
mitigation work plan, climate finance, adaptation, loss and damage, biodiversity, carbon
markets (Singapore boosts UN climate targets, confirms net zero by 2050)
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Singapore’s selected SDG indicators:
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IPCC synthesis report for the sixth assessment report (2023) → do you accept that
progress is not as strong as it should be?
11.6 What can I do?
- Singapore Green Plan → “a whole-of-nation sustainability movement”
- Need to look at the scale of the problems you are trying to solve
- Individual level (not using straws/plastic bags) → training your mentality to think in a
higher level/larger scale
- Action for change: learn, then enhance your impact
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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 workplace/community
Participate to suggest practises at higher levels e.g. Singapore Green Plan
Conversations
About 50 groups interested in upstream solutions for the environment (saw areas that
are not targeted and wanted to help)
NUS environmental student groups → campus-wide groups, residential life groups,
academic programme groups
NUS Toddycats Telegram channel → habitat enrichment, public engagement, guided
nature events, mangrove cleanups
Climate/eco-anxiety: distress about climate change and its impact on the landscape and
human existence
Yet, actions by individuals can have only limited impact on carbon emissions →
consumers are guided by a system of thought and action that is shaped in large part by
corporations
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Wrap-up
Lecture 12
12.1 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
1. Link between block 2 and observe, explain, test
- Traditionally, a theoretician was someone who developed testable theories.
Nowadays, a great deal of the work of a theoretician is putting together
mathematical and computer models
- (L5) Fourier 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/the
interior of the planet the Earth would be much cooler than it is
- Correctly identified that the atmosphere must play a role and said “the Earth is
kept warm because air traps heat, as if under a pane of glass” (not accurate but
the gist is correct)
2. Link between block 2 and authority
- Authority in the sense of a person/organisation having political or administrative
power and control. There is another meaning of “authority”, which is “an expert in
the field”.
- 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
- Is a danger that scientific consensus could be seen as an argument from the
authority (frequently articulated by climate change deniers)
- (L7) Authority can be abused e.g. John Sununu
- Authority and consensus are different e.g. Lindzen had the authority since he had
experience with climate science but his claim of solar source causing rise in
temperature was not confirmed by the scientific consensus
3. Link between block 2 and scientific revolution
- (L5) Paradigm found in the alchemical writings of Becher and Stahl were
replaced with the ideas of Lavoisier
- 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
4. Link between block 2 and invention of a new instrument leads to new discoveries
- Ratio spectrophotometer built by Tyndall
- Most important instrument in climate science has been the computer
5. Link between block 2 and scientific community
- Scientific community is a prerequisite for the emergence of consensus
- The Royal Society of London is an early example of such a scientific society →
greatly influenced by Francis Bacon and his vision of experimental science
6. Link between block 2 and industrial revolution
- The reason why we use the average temperature between 1850 and 1900 as a
proxy for pre-industrial temperatures is because:
● Lack of reliable instrumental records to construct a global average
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Do not believe that carbon dioxide emissions from the coal burnt between
the advent of the industrial revolution and this period would have
significantly influenced global temperatures
7. Link between block 2 and L2 (BTDK)
- Importance of considering the necessary comparative information
● Subtracted baseline temperatures, such as the 1850-1900 average, from
global temperature measurements to reveal changes in temperature
● Compared carbon dioxide, methane and nitrous oxide measurements to
past levels to reveal differences
- Where does most of the evidence lie?
● Discussed four datasets (NASA, NOAA, the UK Met Office and the Japan
Meteorological Agency) → agreed extremely well and showed that global
average temperatures are increasing
● Scientists looked for ways of estimating temperature prior to the
instrumental temperature record → proxy methods (tree rings, coral rings,
ice cores) → all in agreement and shows the rapid increase in
temperature
● Projections and analysis found in IPCC Sixth Assessment Report come
from 100 climate models themselves developed from 49 research groups
- Has anyone tried to disprove the claim that climate change is happening
unnaturally?
● Scientists have studied whether temperature increase could be natural
variability & also whether it is due to solar variability and changes in
volcanic activity → evidence not there
- Has anyone tried to disprove the claim that climate change is human caused?
● Dilution of carbon-14, or more accurately the ratio of carbon-14 to
carbon-12, in the atmosphere after the open-air testing of atomic
weapons
● Rate of dilution of the ratio of carbon-14 to carbon-12 can only be
explained by the emission of CO2 through the burning of fossil fuels
which are necessarily devoid(lack of) in carbon-14
- Detecting misinformation, falsehoods and lies
● Doubt mongering by political lobbyists and contrarian scientists deeply
damaged the prospects of action
● Persuasiveness of social media have deeply divided opinion on a topic in
which there is no serious debate in the scientific community
● 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 evaluate information that you might prefer to deny
8. Link between block 2 and L3 (Scientific theories)
- How a scientific theory is developed, then replaced: Phlogiston Theory
- States that when the metal is heated the calx (metal’s true form) is revealed and
the phlogiston is seen to leave the metal
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Early indications that there might be problems with the theory were found in
numerous studies (Boyle in 1673, Lemery in 1675 and Freind in 1709) → showed
that metal gained weight when heated
- Many celebrated scientists did not see as clearly, binded as they were to their
adherence of the phlogiston theory → Lavoisier was able to clearly recognize that
combustion is solely about the reaction with oxygen
9. Link between block 2 and Cause & Effect, Causal Mechanisms
- Cause & effect easily understood by public → reason why James Hansen at the
Senate hearing in 1988 wanted to state that a cause and effect relationship
existed between the greenhouse effect (cause) and observed warming (effect)
- Negative/positive couplings in feedback loops directly describe cause and effect
relationships, and the feedback loops describe forms of causal mechanisms
- Some effects can have more than one cause
10. Link between block 2 and underlying processes, laws and function
- Underlying processes: role of CO2 in absorbing such radiation (discussed by
both John Tyndall and Eunice Foote)
- Laws: use of statistical law when studying human behaviour (relied on this law
when suggesting we are all susceptible to cognitive biases)
- Function: function of plants in the carbon cycle (take up CO2 and as source of
food)
11. Link between block 2 and correlation
- Proxy methods → there are correlations between the different methods, such as
the tree-ring widths/coral band widths and temperature
- Seasonal variation in atmospheric CO2 negatively correlated with the rates of
photosynthesis in the biosphere, particularly the northern hemisphere forests
- Correlation is not due to a causal link → 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
12. Link between block 2 and scientific models
- Some mathematical models, like the single-layer model, are not really used for
science, their purpose is for teaching
- Virtually all models nowadays are computer models
13. Link between block 2 and contemporary scientific research
- Supercomputers are extremely expensive and their energy costs are very
demanding → scientists are beginning to be concerned as to whether the carbon
footprint of completing a climate model simulation is ethically sound
14. Link between block 2 and uncertainty & confidence levels
- Scientists need to recognize the need to simplify their language to communicate
with non-scientists
- There was a conscious effort by climate scientists to convert the jargon around
confidence and likelihood into language that could be readily understood by
policy makers
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12.2 Illustrate with examples how science has been used to inform climate change related
and/or biodiversity related public policy, public works, infrastructure or public spaces
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Scientific observations for wildlife, measurement of plants etc.
● Would be more randomization, more samples, but fundamentally it is getting a
sample of some vegetation and comparing it
● Look at forest size, set up quadrats (a frame, traditionally square, used in
ecology, geography and biology to isolate a standard unit of area for study of the
distribution of an item over a large area) and camera traps
● Citizen science (increasingly used by scientists around the world for diversity of
measurements) → is scientific research conducted, in whole or in part, by
amateur/non-professional scientists → larger number of observations provides
greater confidence in results, greater immersion, appreciation of understanding of
scientific inquiry
Ecological connectivity study - contemporary scientific research
● When conducting scientific research, it is critical that terms in the original
question under investigation are clearly defined → scrutinise keywords carefully
→ misunderstanding keywords such as connectivity can lead to thinking that we
have successfully established connectivity for wildlife → wrong conclusions
drawn
● Must conduct an objective disassembly of an idea so it can be clearly studied and
understood → now highly appreciated and welcome
Singapore as a ‘petri dish’ - a test bed
● In tiny Singapore there are experiments that you can conduct, there are
programmes you can roll out, and then when you study the effect it is applicable
elsewhere
● From small plots in Singapore where we have tried things, give a lot of hope and
encouragement and ideas about how to fix things in other larger nations
● We are suitable as a test bed because we can get things done quite quickly →
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 etc.
Interaction between science and society and governance by the government
● Inter-ministerial committee on climate change
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If you are pointing out things to the government in a rational scientific manner,
the nature of the interaction tends to be very civilised
Unfortunately, if you have an agenda driven industry pushing misinformation, it is
a really big challenge for educators overseas in the West because they have to
fight all of that
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 will need to test it; this is the scientific method in action at the
government level (e.g. bishan-ang mo kio naturalised canal)
12.3 Describe each of the 8 fallacies put forth in the name of science, providing examples to
illustrate their meaning
1. False anomalies
- Claimant typically fraudulently present some phenomenon as being mysterious,
not explainable by science, then provide their own explanation for the
phenomenon, which is very often an extraordinary claim
- They purposely leave out evidence in support of a regular scientific explanation,
or worse, misrepresent or falsify evidence in support of their own extraordinary
claim
- E.g. crop circles in the middle of crop fields said to be made by aliens or their
spaceships → “tramlines” are purposefully disregarded
2. Questionable arguments by elimination
- Claimant considers evidence that an alternative explanation is wrong to be actual
evidence in support of their evidence for some phenomenon
- Just by eliminating rival explanations does not provide evidence for your favourite
explanation → need to find positive evidence directly in support of it
3. Illicit causal inferences
- Correlation does not imply causation
- Coincidence does not necessarily imply causal link e.g. if you enter a lift as
someone else exits it and then you smell something quite bad in the lift does not
mean the person who just left had anything to do with it
- The most prominent of these are: a simple correlation between A and B, a
concomitant variation between A and B, the fact that A precedes B
4. Unsupported analogies and similarities
- Scientists sometimes use analogies to something that is well understood to help
explain something puzzling → can be fallaciously exploited when the fact that an
explanation works in one case is given as evidence for the correctness of a
similar explanation in another case
- Only careful testing can provide such evidence
- E.g. “much as the moon influences the tides and sunspot activity can disturb
radio transmissions, so do the positions of the planets have an important
influence on formation of the human personality” → zero evidence to be found in
analogy and similarity that the positions of the planets have any important
influence on the formation of human personality
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5. Untestable explanations and predictions
- If an explanation cannot be experimentally shown to be false, then it is not a
scientific explanation
- Many conspiracy “theories” fall under this category
- An anomaly is not evidence → it is an anomaly that requires a falsifiable
explanation
6. Empty jargon
- Conmen can hijack this language and string together a bunch of terms, which
means nothing, in order to try and convince you that something is scientifically
established
7. Ad-hoc rescues
- 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 is not
8. Exploiting uncertainty
- Science, as we know, is fraught with uncertainty, but this uncertainty is Science’s
major strength → science is self-correcting because of this
- Just because something is not 100.000…% certain does not mean that it is not
certain for all practical purposes
12.4 Explain the 3 ways that we cannot use to distinguish science from pseudoscience, and the
4 features that do distinguish science from pseudoscience
- Pseudoscience is not actual science, although it may appear to be, it is fake science
- Ways that cannot be used to differentiate between science and pseudoscience:
1. ‘Hard’ and ‘soft’ science
● Hard science refers to the fields of physical, chemical and biological
sciences
● Soft science involves fields engaged in the study of human behaviour like
sociology, anthropology, psychology, political science etc.
● Both soft and hard sciences aim at explaining phenomena of the natural
world → all fields use rigorous methods of observing, explaining and
testing
2. Along the lines of scientific discipline
● Cannot distinguish between science and pseudoscience just because the
hypothesis, theory or claim may exist within one of the hard or soft
science
● Just because something is in the field of astronomy, does not
automatically mean that its science → nonsense can be promulgated in
any subject area
3. On the basis of the results each produces
● Cannot claim something to be a pseudoscience based on the fact that
ultimately it turned out to be wrong
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Phlogiston Theory → became an obsolete theory after Lavoisier’s work
but was considered “well-establish” theories for its time with various
scientific evidence in support and having been subjected to all the rigours
of the scientific method
Ways that can be used to differentiate between science and pseudoscience
1. When evidence comes to light in science indicating a current explanation
requires revision, a pseudoscience simply ignores it
2. Because pseudoscience is not self-correcting, it rarely develops and matures
3. In pseudoscience it is quite rare for the claims, assertions, or speculations to
change much as time goes by
4. Pseudoscience dismisses valid counter arguments to its claims on the basis that
those criticising it are not willing to consider the possibility that their claim is
correct
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