Climate change feedbacks lead to surge in natural methane emissions

Enlarge / A view of the Pantanal wetlands in Brazil. New research shows a large chunk of global methane emissions are from rotting vegetation in tropical wetlands. (credit: Carl de Souza/AFP via Getty Images)

A 2021 pledge by more than 100 nations to cut methane emissions from anthropogenic sources 30 percent by 2030 might not slow global warming as much as projected, as new research shows that feedbacks in the climate system are boosting methane emissions from natural sources, especially tropical wetlands.

A new trouble spot is in the Arctic, where scientists recently found unexpectedly large methane emissions in winter. And globally, the increase in water vapor caused by global warming is slowing the rate at which methane breaks down in the atmosphere. If those feedbacks intensify, scientists said, it could outpace efforts to cut methane from fossil fuel and other human sources.

Methane traps about 80 times more heat than carbon dioxide over a 20-year period, and scientists estimate it’s responsible for 20 to 30 percent of climate warming since the start of the industrial age, when atmospheric methane was at a concentration of about 0.7 parts per million. It has zig-zagged upward since then, spiking with the first fossil gas boom in the 1980s, then leveling off slightly before a huge surge started in the early 2000s. The amount of methane in the atmosphere reached about 1.9 ppm in 2023, nearly three times the pre-industrial level.