Methane is one of the gases involved in the greenhouse effect, with a potential exceeding that of notorious carbon dioxide by 25 times. Its atmospheric concentration, however, is 210 times less, so its contribution to the greenhouse effect is a mere 12% of carbon dioxide's.
One more thing on global warming and I'm done. Just curious, does anyone know how much sulfur, ect a volcano eruption puts into the atmoshere?? And as far as the oceans warming, anyone know how many underwater volcanos researchers think are lurking beneath the surface??? Man doesn't hold a candle to nature, I would give natural occurances the edge in adding that 1 DEGREE INCREASE IN WORLD TEMP OVER THE LAST ONE HUNDRED YEARS!