Download P Other greenhouse gases – page 1 of 4 Other greenhouse gases

Other greenhouse gases
So far we have come to the conclusion that an increase in the levels of carbon dioxide
in the atmosphere accompanies a rise in global temperature. We are now going to
look at some data from other greenhouse gases to see if they have the same effect.
CO2 /ppmv
300
250
CO2
2
200
-2
∆T
∆T/ °C
0
-4
700
-6
CH4
CH4 /ppbv
600
500
400
300
0
50
100
Thousands of years before present
150
Graphs obtained from Antarctic ice core records of local atmospheric temperature
and corresponding air concentrations of carbon dioxide and methane for the past
160,000 years
(Data source: Intergovernmental Panel on Climate Change.)
1. As the air temperature increases, what happens to the amount of methane in the
atmosphere?
2. Using the data from the graph to support your answer, do you think the amount of
methane in the atmosphere could lead to global warming?
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Other greenhouse gases – page 1 of 4
The following graphs show estimated historical concentrations of major greenhouse
gases, over the last 250 years.
CH4 concentration /ppbv
1800
Methane
1600
1400
1200
1000
800
600
1750
1800
1850
1900
Year
1950
2000
1850
1900
Year
1950
2000
1850
1950
2000
N2O concentration /ppbv
310
Nitrous oxide
300
290
280
1750
1800
CFC-11 concentration /ppbv
0.3
CFC-11
0.2
0.1
0
1750
1800
1900
Year
Graphs showing estimates historical concentrations of major greenhouse gases, over
the last 250 years
(Data source: Intergovernmental Panel on Climate Change.)
3. In which year did the level of methane in the atmosphere first start to increase?
4. Describe what happened to the amount of methane in the atmosphere after 1950.
5. When did CFC-11 start to build up in the atmosphere?
6. The amount of nitrous oxide in the atmosphere has steadily increased during the
last 250 years. When did the rate of increase suddenly change?
7. Do you think that any of the above gases could be linked to global warming? You
must explain your answer.
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The amounts of greenhouse gases in the atmosphere have increased dramatically over
the last fifty years. This is mainly because of increased human population and
activities, such as man-made chemicals and combustion.
380
Ice core
measurements
360
CO2 emissions/ppmv
✵
340
South pole
Fossil CO2
emissions
Mauna Loa
CO2 emissions/ppmv
Key
One hundred
year running
mean
320
360
6
340
4
320
2
300
0
Fossil CO2 emissions/GtC/yr
380
280
1850
1900
Year
1950
2000
300
✵
280
✵
✵
✵
✵
✵
260
800
1000
1200
1400
Year
1600
1800
2000
Graphs showing carbon dioxide levels
(Data source: Intergovernmental Panel on Climate Change.)
The table below lists the main man-made sources of these gases. Greenhouse gases
also occur naturally.
Greenhouse gas
Sources due to human activities
Carbon dioxide
Burning of fossil fuels
Deforestation
Methane
Bacteria in rice paddy fields
Released from natural gas and oil wells
Landfill – (getting rid of waste)
Domestic animals – mostly cattle
Coal mining
Biomass burning
Chlorofluorocarbons (CFCs)
Refrigerants
Aerosols
Nitrous oxides
Fertilisers
Combustion of fuels in cars and power stations
Biomass burning.
Sources of greenhouse gases
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Other greenhouse gases – page 3 of 4
One of the big problems with greenhouse gases is that once they enter the atmosphere,
it is a long time before they leave. The table below shows how long each molecule of
gas will stay in the atmosphere.
Atmospheric lifetime (years)
Carbon
dioxide
Methane
CFC-11
Nitrous
oxide
50–200
10
65
150
Atmospheric lifetime of greenhouse gases
8. Which greenhouse gas stays in the atmosphere for the shortest length of time?
9. Which greenhouse gas is the hardest to get rid of?
10. You work for the local council and have been invited to give a speech on global
warming and the greenhouse effect. Members of the audience will be local
residents and business people. Prepare notes for the speech.
Your speech should include the following points;
■ What the greenhouse effect is;
■ The likely causes of recent global warming (over the last fifty years);
■ Your plans to help reduce global warming by local actions;
■ The problems you expect to find when carrying out these plans; and
■ The time-scale needed to carry out these plans.
You may like to include a visual aid to use during your speech.
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Other greenhouse gases – page 4 of 4
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