Nevertheless, a recent study discovered that wetlands have been releasing more and more methane (CH4) since 2000, with emissions reaching unprecedented levels in 2020 and 2021. The study was published in Nature Climate Change on Monday.
According to the study’s authors, the strong positive wetland CH4 feedback is likely to occur under the current warming and precipitation variations brought on by climate change.
Methane has 84 times the warming effect of carbon dioxide during a 20-year period, which makes it a climate worry. Targeting methane emissions provides a chance to maintain warming within 1.5 to two degrees over pre-industrial levels in the short term, but it also evaporates in the atmosphere after about a decade.
Yet, wetlands that are promoted as carbon sinks start to leak more methane as the temperature warms, according to Carbon Brief. This can occur as tropical wetlands expand under more intense precipitation, as permafrost wetlands in the Arctic melt, as methane-releasing microbial activity rises, or both.
According to a USGS study published in early March, under moderate to extreme warming, methane emissions from freshwater wetlands might rise by two to three times. Governments and scientists must take this into consideration.
According to research co-author and USGS Research Ecologist Sheel Bansal, if we determine how much to cut our methane emissions without taking into consideration how warming is altering the processes producing natural emissions, we risk falling short when accounting for our mitigation efforts.
The Nature Climate Change study examined both current events and potential future developments. According to Carbon Brief, researchers developed a model that predicts future emissions from both permafrost and tropical wetlands using both field measurements and reanalysis data that merged observations and models.
They found that since 2000, wetland methane emissions have increased by 1.2 to 1.4 million tonnes annually, exceeding the worst-case scenario emissions pathway’s projection of 0.9 million tonnes annually.
Compared to the years 2000 to 2006, emissions climbed significantly more in 2020 and 2021, reaching four to 26 million tonnes in 2020 and 13 to 23 million tonnes in 2021. The thawing permafrost is still a problem for the future even if tropical wetlands are currently responsible for most of the emissions increases.
The findings are especially alarming given that wetland methane emissions rise with warming in none of the major publications, including the most recent study from the Intergovernmental Panel on Climate Change.
The authors of the study concluded that coordination between the scientific community on integrating rapidly changing biospheric processes within remaining carbon budgets is a need if we are to stay below 1.5 C and 2.0 C. The advent of a wetland climate feedback underscores this point.
According to Dr. Gabrielle Dreyfus, chief scientist at the nonprofit Institute for Governance and Sustainable Development who was not involved in the study, the data may require more than just the rapid and significant cuts in human methane emissions that the IPCC claims are required to keep global warming to 1.5 degrees Celsius.
According to Dreyfus, the study’s shortcomings suggest that in the future, methods for removing methane may need to be adopted in addition to limiting human-caused methane emissions.
The findings coincide with another paper that was published in Nature Climate Change on the same day. It examined the behavior of all three major greenhouse gases in 167 wetlands throughout the Northern Hemisphere between 1990 and 2022 and discovered that even a warming of 1.5 to 2 degrees Celsius increased the potential for 100-year global warming by 57 percent.
According to the study’s authors, their findings demonstrate that even for a modest temperature increase of 1.5–2.0 C, the major objective of the Paris Agreement, warming diminishes the mitigation capability of pristine wetlands.