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Greenhouse Gases

© Danita LaSage

Methane, which has risen from a pre-Industrial Revolution level of about 0.7 ppmv to its present level of about 1.7 ppmv, is a more powerful greenhouse gas. It absorbs about 60 times as much heat as carbon dioxide. Chlorofluorcarbons (CFCs), a family of synthetic gases used as refrigerants, absorb up to 4000 times as much heat as CO2. These two gases are present in smaller amounts than carbon dioxide, so are often given less consideration. However, over the coming decades, as CO2 emissions are reduced and population doubles, methane, which is produced by major food sources like cattle and rice paddies, may become the major greenhouse gas of concern. And CFCs, which are illegal in the US (except for recovered, recycled CFCs used to maintain older cars) are legal to manufacture in other countries, and there is concern that CFCs are being smuggled into the US.

Ultimately, as environmental regulations in the US and other industrialized nations are tightened, the primary source of global warming is expected to come from poorer, less economically-developed countries, which are largely exempt from international attempts to regulate emissions of greenhouse gases.