CO2 is bad, but what about Methane?

"but methane is arguably worse, at least for world climate. Pound for pound methane traps 21 times as much heat as carbon dioxide, the most common greenhouse gas."

From, "Earth's Uncanned Crusaders: Will Sardines Save Our Skin?" NY Times, Nov 23, 2004


I was searching for something in my library's NY Times database and came across this article. Sardines evidently eat certain phytoplankton which release methane and hydrogen sulfide gas, but over-fishing of sardines has lead to more phytoplankton surviving and releasing more methane.

But I had forgotten that other pollution was more global-warming causing than CO2.

Livestock are responsible for 18 percent of greenhouse-gas emissions as measured in carbon dioxide equivalent, reports the FAO. This includes 9 percent of all CO2 emissions, 37 percent of methane, and 65 percent of nitrous oxide. Altogether, that's more than the emissions caused by transportation.

The latter two gases are particularly troubling – even though they represent far smaller concentrations in atmosphere than CO2, which remains the main global warming culprit. But methane has 23 times the global warming potential (GWP) of CO2 and nitrous oxide has 296 times the warming potential of carbon dioxide.

From Christian Science Monitor