Rising methane: Is warming feeding warming?

Abstract

Methane is the second-most important anthropogenic greenhouse gas after carbon dioxide. The atmospheric burden is rising rapidly. CH4 growth from about 720 ppb in pre-industrial times to nearly 1900 ppb now has predominantly been caused by human activity. This is proportionately a much greater rise than the increase in CO2. With a direct heating impact of about 0.5Wm?2 and around 1Wm?2 if indirect impacts are included, the climate warming consequences of anthropogenic methane emissions are very important.