Nature
There are a number of gases, other than carbon dioxide, which are present in trace amounts in the atmosphere and which are known to aggravate the problems of global warming. Only a few are present in sufficient concentration and have sufficiently strong radiation absorption bands in the appropriate thermal radiation window that contains up to 30% of the upward infrared radiation from the Earth's surface. However practically all these gases are increasing in the troposphere and their total effect may be comparable to that of increasing carbon dioxide. The gases include: methane, nitrous oxide, and chlorofluorocarbons and hydrochlorofluorocarbons. Other gaseous oxides of nitrogen, carbon monoxide, volatile organic compounds and tropospheric ozone and its precursors, which have the potential to be greenhouse gases, are of lesser importance because of their short lives and highly variable concentrations.
Background
The Global Warming Potential (GWP) of various greenhouse gases is a measure of the strength of their warming effects over time. For a period of 20 years, the GWP of one kg of carbon dioxide is 1, of methane is 11, of nitrous oxide is 280, of CFC-11 is 3,400, of CFC-12 is 7,100, of HCFC-22 is 4,300, and of HFC-134a is 1,200.
Counter-claim
Some parts of the world which generate most of carbon dioxide could actually become cooler. The reason is that when coal or wood is burned, there are tiny particles and sulphates released in the troposphere which absorb heat from the sun and actually cool the areas beneath them. Rapidly industrializing countries such as China could suffer markedly from this effect.