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9/29/2010 1 Greenhouse effect and global warming The Greenhouse Effect and The Greenhouse Effect and Atmospheric Warming Atmospheric Warming Why is it called greenhouse effect? What is the difference between the greenhouse effect and real greenhouses?

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Page 1: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

1

Greenhouse effect

and global warming

The Greenhouse Effect and The Greenhouse Effect and

Atmospheric WarmingAtmospheric Warming

• Why is it called greenhouse effect?

• What is the difference between the

greenhouse effect and real greenhouses?

Page 2: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

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• Greenhouse gases make up about 1% of the

earth atmosphere

• Without the greenhouse gases, the earth’s

average temperature would be close to -18°C

The Greenhouse Effect and The Greenhouse Effect and Atmospheric WarmingAtmospheric Warming

Page 3: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

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Most important greenhouse gases

Gas Formula Contribution (%)

Water Vapor H2O 36 – 72 %

Carbon Dioxide CO2 9 – 26 %

Methane CH4 4 – 9 %

Ozone O3 3 – 7 %

Do these numbers imply that CO2 is

responsible for 9-26% of the earth warming?

Greenhouse gases

• Water vapor is the most dominant greenhouse gas.

• Water vapor is the dominant positive feedback in the

climate system and amplifies warming caused by

changes in atmospheric CO2.

• This positive feedback is why climate is so sensitive

to CO2 warming.

Page 4: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

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Main non-gas contributors to the

greenhouse effect: Clouds

How does the altitude of the clouds

influence the greenhouse effect?

• Actually clouds do both

– 1)act as insulation� warming the earth

– 2)reflect insolation� cooling the earth

Clouds and Greenhouse effect

Page 5: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

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COCO22 and warmingand warming

• Why does CO2 receive so much attention in

the climate warming context?

• Carbon dioxide accounts for a significant

fraction of the enhanced greenhouse effect.

• The level of carbon dioxide in the atmosphere

is increasing by more than 10% every 20 yrs

due to human activity.

COCO22 and warmingand warming

Page 6: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

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COCO22 and warmingand warming

• Natural sources of atmospheric CO2

– volcanic outgassing

– combustion of organic matter

– respiration of aerobic organisms

COCO22 and warmingand warming

Anthropogenic sources?

Page 7: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

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Source epa.gov

Source epa.gov

Page 8: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

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COCO22 and warmingand warming

• Natural land and ocean CO2 sinks removed

57% of all CO2 emitted from human activities

during the 1958-2008

• Atmospheric lifetime of CO2 is 50 to 200 yrs.

• Global warming will continue to affect the

Earth for hundreds of years.

What about CHWhat about CH44 and warming?and warming?

• Methane is 25 times more potent as a

greenhouse gas than CO2 (but it’s at lower

concentrations in the atmosphere)

Page 9: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

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What about CHWhat about CH44 and warming?and warming?

• Largest anthropogenic sources of methane

emissions (for USA only):

– decomposition of wastes in landfills

– ruminant digestion

– manure management associated with livestock

– natural gas and oil systems

What about CHWhat about CH44 and warming?and warming?

• There is some uncertainty about the

potential future contributions of CH4 to

global warming.

• Positive feedbacks triggered by elevated

temperatures could release large amounts

of CH4 to the atmosphere.

Page 10: Greenhouse effect and global warming - University of ... 1 Greenhouse effect and global warming The Greenhouse Effect and Atmospheric Warming • Why is it called greenhouse effect?

9/29/2010

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• Let’s now see some of the data…