Methane spends a lot less time in the atmosphere than carbon dioxide; about 20 years after it’s released, most of it will have decayed, while carbon dioxide lingers in the atmosphere for hundreds of years. But methane also generates heat much more readily than carbon dioxide — about 80 times more in its first 20 years in the atmosphere — meaning it contributes significantly towards global warming in the short term. It is good news — sort of — because by the same token, any reductions in methane emissions will have more of an impact on the climate right away.