The document discusses the causes and impacts of climate change. It explains that greenhouse gases like carbon dioxide, methane, and water vapor naturally trap heat in the atmosphere and maintain a habitable temperature on Earth. However, human activities like burning fossil fuels and deforestation have increased the concentration of greenhouse gases, raising global temperatures beyond natural levels and threatening severe environmental and social consequences. While debates continue over the scale and solutions, most experts agree that reducing emissions through renewable energy and carbon pricing can mitigate the risks of climate change.

1. Topic 7
Climate change and energy
production
7.2 Climate change – causes and impacts

2. The Role of Greenhouse Gases
• The average temperature on the Earth is 15oC
• Incoming radiation is low wavelength/ high energy
• The average temperature is maintained by atmospheric
gases trapping or reflecting a fraction of the outgoing
(long wavelength/ low energy) heat radiation
• These (greenhouse) gases include:
– Water vapour (H2O)
– Carbon dioxide (CO2)
– Methane (CH4)
– Ozone (O3)
– Nitrous oxide (N2O)

3. The Role of Greenhouse Gases
Without these naturally occurring greenhouse gases, the average
temperature of the Earth would be approximately -15oC

4. Change in Global Temperature Over Time
This data is taken from measurements of the concentration of the oxygen isotope 18O in
air bubbles trapped in rock and ice. This concentration is temperature dependent but can
only be used to give an indication of temperature change rather than a measurement of
temperature itself

5. Change in Global Temperature Over Time
Vostok is the Russian Antarctic
Science Station

6. Change in Global Temperature Over Time

7. The Role of Carbon Dioxide
• Earth’s atmosphere today ≈ 380 ppm CO2 (0.038%)
• Early Carboniferous Period ≈ 1500 ppm CO2
• Middle Carboniferous Period ≈ 350 ppm CO2
• Earth’s atmosphic temperature today 15oC
• Early Carboniferous Period 20oC
• Middle Carboniferous Period 12oC
Over the last 600 million years, only the later Carboniferous Period and the present age
(the Quaternary Period) have had CO2 levels less than 400 ppm. This means that the
temperature of the Earth today is considerably cooler than for most of geological history.
359 mya
300 mya

8. The Role of Carbon Dioxide
• Levels of CO2 are currently increasing
• CO2 levels have risen from 280 ppm in 1850 to 380 ppm today
• It is widely accepted that this is due to anthropogenic activity
although natural factors may also influence it

9. The Role of Carbon Dioxide
• Factors affecting CO2 concentration:
– Industrialisation and burning of fossil fuels
– Deforestation (particularly rainforest)
– Volcanic activity
– Sunspot activity
Anthropogenic
factors
Non-anthropogenic factors
Do you think there is a correlation between the increasing output of carbon dioxide
due to anthropogenic activity and increasing global temperatures? Can we be certain
that the first is responsible for the second?

10. Anthropogenic Factors
• Burning of fossil fuels
– Coal, oil and natural gas
• Deforestation
– Breakdown of organic matter in biomass and soil
– Burning of biomass
– Reduction in photosynthesis
• Cattle ranching
– Cow farts
• Rice farming in padi fields
– Anoxic conditions allow growth of methanogens
• Use of fertilisers
– Breakdown of nitrogen-rich compounds
CO2
CH4
N2O

11. Global Greenhouse Gas Emissions in 2000
other gases
carbon dioxide
methane
nitrous oxide
9%
1%
Anthropogenic Factors
74%
16%

12. Sources of Carbon Dioxide Emissions
oil and petroleum
coal
deforestation
natural gas
other sources
25%
3%
Anthropogenic Factors
26%
31%
15%
The proportions vary from country to country depending on its economy and energy demands

13. The Effects of Global Warming
Feature Effect
Environmental Effects
Ice and snow Retreat of polar icecaps and glaciers
Coastline Increase in sea level and coastal flooding
Water cycle Increased flooding
Ecosystems Change in biome and species distribution
Societal Effects
Water resources Severe water shortages (conflict)
Agriculture Shifts from drought affected areas
Coastal settlements Shifts due to storms and flooding
Human health Increased outbreaks of disease
The Effects of Global Warming

14. The Effects of Global Warming
• Biome shifts
– Models suggest biomes will shift north/south from the
equator and vertically to higher ground.
– Low-lying biomes such as mangroves may be lost
completely
• Species changes
– Climate change in the past has been slow and allowed
animals and plants to adapt
– There may be migrations, but many obstacles (some
anthropogenic) and lack of suitable habitats may lead
to mass extinctions
– Increased temperature may lead to spread of pests
and tropical disease vectors

15. The Effects of Global Warming
• Weather
– Effects on weather patterns and rainfall are
unpredictable
– Storms are expected to increase in intensity
• Agriculture
– Increasing drought events would reduce crop yield
and affect farmers’ ability to irrigate (especially in
LEDCs)
– Suitable areas for crop growth would be expected to
move north/south from the equator
– Farmers may be forced to change the crops they
cultivate

16. The Effects of Global Warming
• Tourism
– Summer seasons may be extended
– New coastal resorts may develop
– Lack of water resources may be a problem in some
– Winter sports may be curtailed and resorts closed
• Social Issues
– Conflicts over resources (especially water) may be
expected to increase
– Economic changes may occur
– LEDCs will be less able to cope than MEDCs
– Low lying areas (especially in LEDCs – with poor
infrastructure) will be prone to coastal flooding

17. Possible Positive Feedback Mechanisms
1. Melting of polar
ice may result in
less white areas
on the Earth’s
surface
– This may lower the
Earth’s albedo, the
amount of
incoming radiation
reflected into space
– This may lead to
further
temperature rises

18. Possible Positive Feedback Mechanisms
2. The melting of
permafrost in
taiga and tundra
biomes may
release methane
from rotting
vegetation which
is currently
trapped

19. Possible Positive Feedback Mechanisms
3. Increased temperature may increase
decomposition rates therefore releasing more
CO2 into the atmosphere
4. Deforestation may lead to warming and drying
of the climate, leading to further loss of
rainforest
5. Increased forestation in higher latitudes may
further decrease albedo

20. Possible Negative Feedback Mechanisms
1. Increased evaporation in equatorial latitudes
may lead to more water being carried through
the Ferrel and Polar Cells, leading to increased
snowfall at the poles and restore the Earth’s
albedo
2. Increased levels of CO2 may lead to increased
rates of photosynthesis, which in turn would
lower the concentration of atmospheric
carbon

21. Possible Negative Feedback Mechanisms
1. Increased evaporation in equatorial latitudes
may lead to more water being carried through
the Ferrel and Polar Cells, leading to increased
snowfall at the poles and restore the Earth’s
albedo
2. Increased levels of CO2 may lead to increased
rates of photosynthesis, which in turn would
lower the concentration of atmospheric
carbon

22. Pollution Management Strategies
to Reduce Global Warming (Policy)
• Control the release of greenhouse gases
• Reduce the rate of deforestation
• Increase tree planting programmes
• Develop renewable energy resources
• Reduce car use and improve public transport
• Set national limits on carbon emissions
• Use carbon credits and carbon trading to offset
CO2 emissions
• Develop methods to sequester carbon from the
atmosphere (biological and chemical)

23. Pollution Management Strategies to
Reduce Global Warming (Individuals)
• Grow your own food
• Buy locally grown produce
• Use energy efficient products (e.g. light bulbs)
• Reduce heating your house/ improve insulation
• Use less electricity and unplug appliances
• Turn off lights when not in use
• Reduce use of air conditioning and refrigerants
• Don’t waste water (take showers instead of baths)
• Walk and use a bike/ use cars less/ use public transport
• Use biofuels
• Eat less meat
• Get involved in public education/ activism

24. The Kyoto Protocol
• In 1997, 183 countries signed this agreement to try to
keep global greenhouse gases at a stable level
• It came into force in 2005
• Each country’s emissions were divided into credits and
they were allowed to buy and sell them
• Countries are also able to offset their emissions by
planting trees (an alternative to buying carbon credits)
• The US and Australia signed but refused to ratify the
Kyoto Protocol
• Canada signed and ratified it, but has since withdrawn
from its obligations

25. The Future of the Kyoto Protocol
• The original agreement was due to end in
2012
• Representatives of the signatories met in
December 2012 to discuss its future
• It was extended until 2020. Richer nations
agreed in principle to compensate poorer
nations
http://www.youtube.com/watch?v=NAsGnGWZS1M&list=PLITAq0aJinsQLtj9dV3Q1tHoSIK76sczW
http://www.youtube.com/watch?v=xpiM2LuK4O4&list=PLITAq0aJinsQLtj9dV3Q1tHoSIK76sczW

26. The Problems of Debating the Issue
• It is a problem on a global scale
• It includes natural and anthropogenic factors
• The mechanisms (including feedback) are not well
understood
• The processes are occurring over the long term and the
impacts may not have occurred yet
• Many people involved on both sides are affected by vested
interests (consciously and unconsciously)
• Much of the evidence and forward-planning is based on
climate models which have considerable inherent
uncertainty
• Actions are likely to have huge cost implications for a large
proportion of the human population
• A huge amount on information is now available to
everybody (scientists and non-scientists) and much of it is
misleading

27. The Main Players
• Al Gore
– Former US vice president
and presidential
candidate
– Winner of the 2007
Nobel Peace Prize
– Writer of the book and
film An Inconvenient
Truth
http://www.youtube.com/watc
h?v=splKGWuErnM

28. The Main Players
• Bjorn Lomborg
– Danish economist
– Writer of the book and film
The Sceptical
Environmentalist: Measuring
the Real State of the World
– Accepts that human activity
may be affecting climate but
refutes suggestions that this
should be something that
affects the global economy
– Opposes the Kyoto Protocol
and the idea of carbon tax
http://www.youtube.com/
watch?v=Dtbn9zBfJSs

29. The Main Players
• Martin Durkin
– UK film-maker
– Maker of the documentary
The Global Warming Swindle
– Vehemently opposes the idea
that climate change is
anthropogenic
– States a belief that
temperature affects CO2
concentrations rather than
the reverse
http://www.youtube.com/
watch?v=lIjGynF4qkE
http://edroness.blogspot.mx/
2014/05/the-great-global-
warming-swindle.html

30. The Main Players
• Sir Nicholas Stern
– Former vice-president of the World
Bank and current president of the
British Academy
– Author of The Stern Review on the
Economics of Climate Change for
the British government
– Believes that anthropogenic
climate change poses a series
threat to global economic stability
and that the precautionary
principle is warranted
– Believes that carbon taxation and
international agreements are a
sensible way to approach the
problem
http://www.youtube.com/
watch?v=pqLROIKWM2s

31. Questions
1. What are the main greenhouse gases?
2. What role do they play in maintaining global
temperature?
3. Describe 4 different ways in which human
activities affect the concentration of greenhouse
gases in the atmosphere
4. Describe and evaluate strategies to reduce
global warming
5. Evaluate 4 different perceptions of the issue of
global warming