1. Global warming
Key words: combustion, carbon dioxide, methane, deforestation

2. Rising levels of carbon dioxide. Why?
starter
Rising levels of carbon dioxide. Why?
At the moment the change is
seemingly very small
at 0.060C per year

3. How does combustion affect the atmosphere?
Objective
How does combustion affect the atmosphere?
Success Criteria
By the end of the lesson I:
know how combustion affects the
atmosphere
know how living organisms affect the
can explain the consequences of global warming

4. Get the gas right Pollution problem Gas Global warming Carbon dioxide
Acid rain
Sulfur dioxide and nitrogen oxides
Holes in the ozone layer
CFCs (Chloroflurocarbons)

5. The greenhouse effect

6. Draw a diagram and explain the ‘greenhouse effect’
Teacher notes
This four-stage animation can be used to illustrate the principles of the greenhouse effect. Students could be asked to consider the impact of rising greenhouse gases on the natural phenomenon of the greenhouse effect.

7. Atmospheric carbon dioxide
The worry of rising carbon dioxide levels is
that
if the earth warms up then the ice caps
will melt causing sea levels to rise.
There is no evidence of this happening
but it would mean
that low lying areas will flood and parts
of or even whole countries will become
submerged!
Teacher notes
This graph was produced using data sourced from the Mauna Loa Observatory, Hawaii, courtesy of NOAA (the National Oceanic and Atmospheric Administration). More information about atmospheric gases is available at

8. Carbon dioxide levels
Carbon dioxide is one of the most important greenhouse gases because atmospheric concentrations have risen dramatically over the past century. Why do you think this is?
Respiration and combustion produce
carbon dioxide
Photosynthesis removes carbon dioxide
More rice fields and cattle have led to
increased levels of methane in the
atmosphere.
Increased levels of greenhouse gases
(carbon dioxide and methane) may
cause global warming as a result of the
Greenhouse effect
Burning fossil fuels (combustion),
deforestation and
flooding land for the construction of hydroelectric dams
have all contributed to rising levels of
carbon dioxide.
Another greenhouse effect harming the
environment is methane which is produced
by cows in large amounts and by rice fields!

9. Global warming and greenhouse gases
One of the greatest threats caused by air pollution is global warming. Global warming is caused by a build-up of greenhouses gases, which leads to an increase in the Earth’s temperature.
A greenhouse gas is an atmospheric gas that absorbs infrared light.
Key greenhouses gases include:
carbon dioxide (CO2)
Teacher notes
See the ‘Climate Change’ chemistry presentation for more information on greenhouse gases, the greenhouse effect and global warming.
methane (CH4)
water vapour (H2O)
nitrous oxide (N2O)

10. Global warming
Most fuels contain
carbon
Carbon dioxide is released when fuels like gas, coal, oil, petrol and wood are burned.
Greenhouse gases cause the temperature of the Earth to rise slowly.
This causes climate change.
Methane released from cattle and rice fields is also a greenhouse gas.
Carbon dioxide
released when fuel
burned
Extra carbon dioxide
in the air slows down
heat loss from Earth
Climate change

11. What is the carbon sink?
Before the industrial revolution, carbon dioxide levels were usually kept in check by the carbon sink – forests and oceans that capture and store carbon.
forests – All green plants absorb carbon dioxide as part of photosynthesis. The absorbed carbon is only released back into the atmosphere when the plant dies and rots, or is burned.
oceans – Carbon dioxide dissolves in sea water, depending on the temperature and pressure. Tiny marine animals called phytoplankton extract carbon from the carbon dioxide to make their skeletons and shells.

12. The carbon sink

13. Deforestation
Deforestation can have a contributing effect on global warming.
Large scale deforestation (especially in tropical areas) has led to an increase of carbon dioxide in the atmosphere (when trees die they release their CO2)
It has also reduced the amount of CO2 that is removed from the atmosphere
Leads to loss of biodiversity.
some organisms lost may have
been needed in the future!

14. Preventing global warming
Energy efficiency means less fuel burned to make electricity.
Fuel cell buses.
Renewable energy sources like water power, solar, wind farms, bio fuels.
Nuclear power.
The Kyoto agreement to reduce CO2 emissions.
Reduction in large scale deforestation

15. Exam Questions
Give one reason why deforestation increases the carbon dioxide concentration of the atmosphere. (1 mark)
Explain, as fully as you can, why the increasing concentration of carbon dioxide in the atmosphere is causing global warming.

16. How does combustion affect the atmosphere?
Objective
How does combustion affect the atmosphere?
Success Criteria
By the end of the lesson I:
know how combustion affects the
atmosphere
know how living organisms affect the
can explain the consequences of global warming