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The greenhouse effect is the name applied to the process which causes the surface of the Earth to be warmer than it would have been in the

absence of an atmosphere.

Global warming or the enhanced greenhouse effectenhanced greenhouse effect

is the name given to an expected increase in the magnitude of the greenhouse effect, whereby the surface of the Earth will amost inevitably become hotter than it is now.

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About 70% of the sun's energy is radiated back into space.

But some of the infrared radiation is trapped by greenhouse gases

and warms the atmosphere,

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Water vapour accounts for 98% of the natural Greenhouse effect.

Water vapour has lower ‘radiative forcing’ properties than some other atmospheric gases such as

carbon dioxide, methane and nitrous oxide which are naturally present in the atmosphere

in small quantities.

Since the Industrial Revolution the proportion of these gases has increased significantly.

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Enhanced Greenhouse Effect

164%

219%

311%

46%

CO2

CFCsN2O

CH4

1 Carbon Dioxide > fossil fuels, vehicle emissions, forest clearance2 Methane > rice cultivation, biomass burning, digestive fermentation,

termites, sewage, landfill, natural gas production3 CFCs > aerosol propellants, refrigerants, foaming agents4 Nitrous oxide > nitrogen fertilisers, industrial pollution

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Carbon Dioxide: 280 ppm 360 ppm (+30%)

Methane: 0.70 ppm 1.80 ppm (+145%)

Methane c25 x effect of CO2

CFCS (chlorofluorocarbons) recent significant decrease due to concern about OZONE LAYER

CFCs c10,000 x effect of CO2

BUT

CONCENTRATION CHANGES SINCE 1750

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°C Temperature anomalies from the period 1961-1990