Methane Feedback Loop Beyond Humans' Ability to Control May Have Begun—NOAA

A methane feedback loop that is beyond humans' ability to control may have begun, scientists with the National Oceanic and Atmospheric Administration (NOAA) have said.

Methane is a powerful greenhouse gas emitted into the atmosphere from both human activities and natural processes. It is the second biggest contributor to climate change after carbon dioxide.

According to the NOAA, methane is 25 times more powerful at trapping heat in the atmosphere compared to carbon dioxide. While it remains in the atmosphere for a much shorter time than carbon dioxide, it has a huge impact on the rate of climate change.

Research published by the NOAA now shows that 2021 saw the largest annual increase in atmospheric methane levels since measurements began in 1983.

Xin Lan, a research scientist at the NOAA, told Newsweek that after 2006, the majority of methane emissions produced were caused by natural wetlands and man-made emissions. Natural wetlands produce methane when organic matter decays , while and man-made emissions are caused by livestock, waste and landfills.

It is difficult for scientists to determine which emissions come from which source. However, natural methane production is accelerated by rain and varying temperatures, which climate change is already causing.

Lan said that because the Earth's climate is already warming the methane produced from natural wetlands is only set to increase. This signals the beginning of a feedback loop—an ongoing cycle that cannot be broken.

"From natural processes, we know that wetland methane emissions are sensitive to change in precipitation and temperature," she said. "Methane production from microbes increases with increases in global temperature which is driven by long-term greenhouse gas emissions. More atmospheric methane, in turn, can further warm up the earth. That's the feedback loop we are referring to."

In a statement, the NOAA said this loop could be beyond humans capabilities to control

Lan said that in 2020 and 2021 the Earth was in a 'La Nina' phase—a period when the ocean surface cools, subsequently causing lower temperatures: "We typically see more rainfall over terrestrial tropics i.e. larger wetland areas during La Nina year. We know that 2021 is the warmest La Nina year on record. That's why we are concerned about the possibility of climate feedback.

"Unfortunately, we may not be able to know for sure that it is climate feedback because of the limitations on current observational capability on wetland methane emissions."

However, Lan said that if there is climate feedback happening, it means the long-term warming in global temperatures has already contributed to more greenhouse gas emissions.

"That would be an extra challenge for us in combating the impact of climate change," Lan said. "Reducing fossil methane emission is a straightforward approach to slow-down to revert the growing trend in atmospheric methane. But given the longevity of CO2 in the atmosphere and the much larger fossil CO2 emissions, we should also take immediate actions to reduce fossil CO2 emissions. Unfortunately, it is difficult to understand and control natural methane emissions."

While it is hard for scientists to differentiate which emissions come naturally, they estimate that about 30 percent of methane emissions are caused by fossil fuel production. These emissions tend to be easier to control with technology, the NOAA said in a statement.

"It's going to take a lot of hard work to reverse these trends, and clearly that's not happening," Ariel Stein, director of the NOAA's Global Monitoring Laboratory, said in a statement. "So it is crucial that we continue to sustain integrated and robust monitoring and verification systems to help assess the current state of the atmospheric greenhouse gas burden, as well as determine the effectiveness of future greenhouse gas emission reduction measures."