- The average energy reaching the surface of the earth from the sun
is around 343 Watts per square meter. As this passes through the atmosphere,
around 6% is scattered back to space and about 10% is reflected from land
and ocean surfaces. The remaining 84% (288 Watts per square meter) remains
to heat the surface of the earth.
- To balance this, the Earth must radiate
on average the same amount of energy back to space. However, the so called
Greenhouse gases such as water vapour, carbon dioxide and other minor gases
absorb some of the radiation leaving the surface and re-radiate it back to
the surface causing the earth to be warmer than it would otherwise be.
- The warming effect of greenhouse gases in the atmosphere was first recognised
in 1827 By Jean Baptiste Fourier (of mathematics fame)
.
Extracts from 'Global Warming The complete briefing' 3rd Edition. John Houghton CUP 2004
