Atmospheric methane levels are rising, and isotopic ratios within the greenhouse gas suggest that the tropics may be to blame.
Although methane decays more quickly in the atmosphere than carbon dioxide does, it rapidly absorbs heat and is a potent greenhouse gas. In 2007, after nearly 2 decades of slowed growth in atmospheric methane levels, the amount of this gas in the air began to rapidly rise.
Historically, rises in methane levels have been driven by fossil fuel leaks. However, earlier this year, researchers at the National Institute of Water and Atmospheric Research in New Zealand found that biogenic sources, which they thought were from agriculture, were the primary cause of the uptick. Read more.