The Atmosphere and Atmospheric Pollution

Ordinary air contains a variable amount of water vapor, but its composition on a dry basis by volume is 78.08% N2, 20.95% O2, 0.934% Ar, and, presently, only 0.036% (360 parts per million, ppm) CO2, plus minor amounts of Ne, He, CH4, Kr, H2, N2O, and Xe. Nevertheless, carbon dioxide is believed to exert a major influence on climate through the greenhouse effectsunlight penetrates the atmosphere, is mostly absorbed by the Earth, and is reemitted as infrared radiation, but an important frac- 

5 °C by the year 2100 have been predicted on the basis of revisions of various models (earlier versions predicted a 1.5 to 4.5 °C increase by the mid-twentyfirst century). At the time of writing (1996), an international consensus is emerging to the effect that global warming is indeed occurring, and that it is probably correlated with the atmospheric CO2 concentration. 

About 40% of the world s energy demand is met with coal. 

The United Nations Panel on Climate Change made several recommendations to limit C02 emissions, including the following  

The reality is, however, that it will be politically difficult or impossible to stabilize CO2 emissions at 1990 levels, let alone bring about a significant reduction. Rubin et al.is discuss some realistic mitigation options. 

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