Firas A. IB-1 A

1. Defenition of the greenhouse effect

The greenhouse effect is the rise in temperature that the Earth experiences because certain

gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for

example) trap energy from the sun. Without these gases, heat would escape back into space

and Earth’s average temperature would be about 60ºF colder. Because of how they warm our

world, these gases are referred to as greenhouse gases.

2. Golbal warming potential

Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas

is estimated to contribute to global warming. It is a relative scale which compares the gas in

question to that of the same mass of carbon dioxide (whose GWP is by definition 1). A GWP

is calculated over a specific time interval and the value of this must be stated whenever a

GWP is quoted or else the value is meaningless.

3. Storm frequency

While most climatologists do not believe that global warming will increase the frequence of

hurricanes, they are in accord that with more heat stored in the oceans, the intensity of these

storms will increase. Melting ice in the Arctic may destablize the climate of the Arctic in one

way, but overall ocean temperatures will increase with global warming.

Heat stored in oceans

Melting ice in the Arctic

Overall ocean tempratures wil inacrease (especially the surface, causing storms)

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Firas A. IB-1 A

4. Methane, Carbon dioxide and CFCs

CO2 is not the only man made gas of concern.  Others include methane (industry, garbage,

cattle raising etc), nitrous oxides (a byproduct of combustion - comes primarily from

automobiles), and of course CFC's. Shown in the table below are the concentrations of

anthropogenic greenhouse gases in 1800 before the industrial revolution compared to the

values measured in 1999.  Also shown is the rate of change and the average lifetime of one of

these gases in the atmosphere.  So while CFC's have a small concetration they are relatively

inert in the atmosphere, lasting 50 to more than 100 years.

Gas 1800 1999 Change/year Atms. Lifetime

Water Vapour 3000  ppm 3000 ppm unknown ppm unknown

Carbon Dioxide 280 ppmv 353 ppmv 1.8 ppm (.5%) 40 years

Methane 0.8 ppmv 1.75 ppmv 0.015 ppm (.9%) 11 years

Nitrous Oxide 288 ppbv 310 ppbv 0.8 ppb (.25%) 130 years

CFC-11 0 280 pptv 9.5 ppt (4%) 55 years

CFC-12 0 484 pptv 17 ppt (4%) 116 years

Table: http://www.environmentalsciences.homestead.com/greenhousegases.html

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