BA Festival - Walker Institute school talk on science of climate change
Climate Change – a detective story
Science presented by 2 detectives, searching out clues/evidence to find the TRUTH.
Do we need something playing in the background as people come in to the lecture theatre?
---------------------------------------------------------------------------------------------------------INTRODUCTION
THE “VICTIM”
Detective 1: Ladies and gentleman, a terrible crime has been committed. The crime is GCH –
Grievous climate harm. But just how bad is the victim, who has committed the crime and what
does it mean for al of us. With your help we can solve this puzzle.
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Earth with thick white line around it.
**Interactive voting-Do you believe that a crime has been committed, do you believe that our climate is
changing?
------------------------------------------------------------------------------------------------------------THE EVIDENCE FOR WARMING
Detective 1: First we had better check out the state of the victim.
Reports of something weird happening to our climate.
Detective 2: searches for evidence CLIMATE CHANGE – UK EXAMPLE
Have any of you noticed anything suspicious about the climate change in the UK?- examples of
observable changes in the UK.
Detective 1: but that’s just the UK, what evidence is there for warming elsewhere?
GLOBAL TEMPERATURE RECORD
Climate change is being felt across the globe - scientists use the global mean temperature as a
basic indicator of climate change.
We only have enough direct observations from thermometers to measure global temperature
from 1850.
This look suspicious, we can see warming here, but the warming hasn’t been steady. There have
been some periods of cooling, but in the last 50 years the warming seems to be accelerating
 global temp increase graph animation
Detective 2: I’ve just had reports of other evidence coming in showing the state of the victim.
OTHER EVIDENCE FOR WARMING
 Images- evidence of warming- arctic sea ice melt, snow cover melt, mountain glaciers…
 Images- consequences of warming- sea level rise (thermal expansion)…
Warming is unequivocal- there is no doubt that the earth is heating up.
Detective 1: that warming really sounds pretty small – is the victim as badly hurt as we thought?
RECENT WARMING IS UNUSUAL
Although there are natural variations in the temperatures, this recent warming is unusual
 Graph of extended record – we haven’t experienced warming like this for at least the last
1300 years (historical events pointed out to put time in context).
Detective 2: but how do you know this if thermometers were only invented at the start of the 17 th century?
 ‘Proxy’ measurement methods have been used- tree ring measurements, ice-cores, coral,
pollen.
Detective 2: Not just warming, other aspects of climate are changing
o
Rainfall changes – mid and high latitudes are getting wetter, sub-tropics getting drier.
Re-cap bits of evidence in a crime investigation “meeting” – DISTINCTIVE MUSIC.
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recap of evidence – slide with pieces of a jigsaw fitting together
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SOMETHING UNUSUAL IS HAPPENING TO OUR CLIMATE
------------------------------------------------------------------------------------------------------------------------ -------------------WHAT IS CAUSING THE CURRENT WARMING?
Detective 1:- Okay – so we know the victim is in trouble, but who has committed this terrible crime. How
do we know what is causing the warming?
**Interactive voting- who believes that global warming is natural rather than due to human activities?**
THE SUN
Detective 1: There are reports that the warming is all due to changes in the sun’s activity.
 Movie of solar activity
 Graph of solar activity
 Graph of solar irradiance on original global temperature graph (up to…)
**Interactive voting- who thinks that the sun is probably responsible for the warming over the last
century?**
Detective 2: but look the graph stops at xxxx, that looks a bit suspicious …. Lets see what happened over
the last YY years
 Graph extended- non-match
Detective 1: Good work, so that rules the Sun out of the suspects list.
VOLCANOES
Detective 1: What else could cause changes in climate? Haven’t volcanic eruptions have an effect on the
global temperature? Let’s see what evidence we can find.
 Here’s the global temperature record and the arrows show when major volcanic eruptions
occurred. You can see the cooling effect of volcanoes and without these cooling points, the
temperature would probably be even warmer!
Detective 2: O.k., so volcanoes are off the suspect list. But if it’s not because of the sun’s activity and it’s
not because of volcanoes, then where is the warming coming from. It must be something to do with how
the earth maintains it’s temperature…
THE GREENHOUSE EFFECT
Detective 2: explain the natural greenhouse effect
The Greenhouse Effect- Earth surface and atmosphere is heated by the sun – the energy from the Sun
has short wavelength so passes through the atmosphere. Earth’s surface gives off energy – this has long
wave length, there are gases which exists naturally in the atmosphere– we call them greenhouse gases:
the main ones are water vapour, carbon dioxide, methane, nitrous oxide – they absorb some of this
outgoing longwave radiation. This keeps the temperature of the earth at a level to support life. This is the
natural Greenhouse effect, and without these gases, earth’s average temperatures would be a chilly 20C.
 Diagram of natural greenhouse effect
Detective 1: so there are gases in the air that trap heat and keep the Earth warm, so what gases do this?
 Diagram showing the natural greenhouse gases.
INCREASE IN CONC OF SOME GHGS
Detective 1: well maybe the warming we’ve seen is due to a change in these greenhouse gases?
An increase in GHGs would lead to more heat being trapped and more warming – sounds like a likely
suspect
 Diagram - Enhanced greenhouse effect global warming
Detective 2: Yes, I think you’re right, we’ve got evidence here of a dramatic rise in carbon dioxide over the
last 150 years. There’s also evidence coming in now from Antarctic ice-cores.
 Picture of someone drilling into Antarctic ice sheet
From bubbles of air trapped in the ice we can get information about the amount of carbon dioxide in the
atmosphere going back nearly a million years.
 CO2 graph – show CO2 and temperature from ice core data.
You can see CO2 going up and down – these are natural cycles that coincide with ice ages – look you
can see CO2 and temperature go up and down together.
But just look at this, in the last 100 years we’ve seen the amount of carbon dioxide rocket. In fact CO2
levels are higher now than they have ever been over the past 650,000 years!
 On previous slide add in the recent rapid increase
And it’s not just carbon dioxide that has increased, other greenhouse gases - methane and nitrous oxide
- have increased dramatically too.
WHERE ARE THESE GHGS COMING FROM?
Detective 1: But where are these greenhouse gases – like carbon dioxide and methane - coming from?
Since the industrial revolution, people have been burning more and more fossil fuels like coal, oil and gas
and these release carbon dioixde into the atmosphere. Co2 is also given off when trees are chopped
down. Methane – another greenhouse gas that is increasing in the atmosphere is given off by farting
cows (and burping too!), from rice paddies and from land-fill sites.
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Pie chart and photos of GHG sources
**Interactive voting- which sector is the fastest growing source of greenhouse gases in the UK? (a)
energy supply (b) domestic housing (c) aviation**
Detective 2: Wait, some more evidence coming in about something called global dimming.
 Global dimming
Burning coal also releases small particles into the atmosphere called aerosols. They reflect sunlight and
cause cooling. So they act a bit like the natural aerosols from volcanos. Well if they’re increasing that
would actually lead to cooling – I’m confused!!
HOW DO SCIENTISTS WORK OUT HOW THESE DIFFERENT FACTORS (Sun, volcanoes, GHGs,
aerosols) AFFECT CLIMATE?
EXPLAIN CLIMATE MODELS
Scientists use global climate models- like the virtual world’s created in computer games, scientist
construct incredibly complex computer models of the earth’s climate system.
So, to model the Earth’s climate system we have to represent the atmosphere, the oceans, ice, the
energy coming in from the Sun and how it interacts with the atmosphere, how clouds and rain form, the
land surface and of course the things that people are putting into the atmosphere.
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Picture of the atmos and ocean, then add in other components – land, clouds, ice,
vegetation/land surface, human activity
There are physical laws that control how air, heat and moisture move around in the atmosphere and it is
these physical laws that form the basis of a climate model.
Isaac Newton – the famous British physicist – studied the effect of gravity on apples and also how the
planets move. One equation you might be familiar with is Newton’s 2nd law, F=ma, but this applies just as
much to the way the atmosphere and oceans move as it does to apples.
 Isaac Newton, then basic equations which fade out to show words which describe the
equations.
The models also include physical laws that control how radiation from the Sun interacts with that
atmosphere and clouds, how clouds and rain form.
All these complicated equations can only be solved by dividing the world into a 3-d grid the land.
 3-D grid
There are so many equations involved and so many calculations at all these grid points across the globe
and up into the atmosphere, that supercomputers, with more power than 1000s of playstations are
needed to run these models.
 Cartoon of equations being fed into a computer – first put in natural factors (Sun, volcanoes)
 Graph of 20th century temp change with just natural forcing
Natural factors the the Sun and volcanoes can’t explain the 20th century warming
 Cartoon of equations being fed into a computer – with natural factors (Sun, volcanoes) + GHGs
 Graph of 20th century temp change with natural + anthropogenic forcing
It’s only when you factor people’s activities in that you can match the 20 th century warming, so people
ARE causing the warming.
Recap evidence, music
People are altering the climate.
----------------------------------------------------------------------------------------------------------------------------- -------------HOW WILL CLIMATE CHANGE IN THE FUTURE?
Dectective: so what does this mean for the future?
Scientists run climate models into the future to help understand how the climate may change in the future.
The future climate will be dependent on how much and what type of energy we use, how much we travel,
what kind of new technologies will emerge and how much populations may grow, scientists- alongside
economists and sociologists- create future scenarios. This will dictate the forcing of the climate, and how
the climate will respond.
 Flow diagram of this process
**interactive voting- how much do you think the global temperature might warm during this century?**
 Graphs of future change – showing range
Fact - climate change will get worse during this century.
**interactive voting-If the world warms by 4C, when was it last that warm?**
 Animation of global temp change over last 10 million years
So we are taking the world into temperatures that we haven’t seen for millions of years.
Temperature won’t warm the same everywhere, poles and high latitudes warm more.
Rainfall patterns will change – dry areas get drier, mid and high latitudes get wetter.
EXTREMES
Climate change will also lead to more extreme events like flooding and heatwaves.
Let’s look at the example of UK summer temperature.
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Animation of pinball activity
Let’s imagine that each ball is the UK summer temperature for the last 50 or 100 years. So you see a
spread of temperature and the distribution has the well-know normal distribution. The mean summer
temperature is xx degrees, but obviously some summers are warmer than this and some are cooler. You
can see that about 5% (or 1 year in 20) the UK summer temperature is greater than YY.
Now let’s add in the effect of climate change which is shifting the whole distribution. Average summer
temperature might increase by 2 degrees, but just look what happens to extremely warm summers, now
NN years in 20 are warmer than YY degrees. So what we think of now as an extremely warm summer will
become the norm as global warming progresses.
A single warm summer doesn’t prove global warming, but there is evidence that extreme events will
become more likely, more severe.
The same thing applies to rainfall – more droughts and floods.
CLIMATE PRESENTED AS WEATHER FORECAST
Here’s the climate forecast for the next 50 years
 Show temperature increase as an animation – so you see red spreading across the world – add
in symbols for heatwaves
 Show rainfall changes as an animation – you see some areas turning blue and some brown, add
in symbols for heavy rainfall/flooding and drought
---------------------------------------------------------------------------------------------------------------------------------------IMPACTS
Still to be worked on ……….
------------------------------------------------------------------------------------------------------ --------------------------------A VISION OF THE FUTURE
Detective : well the victim looks bad and it looks like things will be worse, so does this mean that we’re all
doomed and there’s nothing we can do about climate change?
We can do something if we act now- we can start reducing the amount of CO2 we produce (mitigation)
and we can prepare for and deal with the climate change that will happen (adaptation).
 Examples of how communities are already adapting to climate change
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Examples of non-fossil fuel energy
Prevent rainforests from being chopped down
Technology examples to reduce the amount of CO2
How we can individually reduce our carbon footprint
examples that apply to them- dancefloor etc.
So, what is your vision of the future??