A record 2020 heatwave triggered the release of fossil methane gas leaked from known rock formations in Siberia. Since methane is a potent greenhouse gas itself, researchers fear this could be part of a climate feedback loop: where more heat triggers more greenhouse gas emissions and even more heat. 

Methane is the second most abundant anthropogenic greenhouse gas after carbon dioxide (CO2). It’s 25 times as potent as CO2 at trapping heat in the atmosphere and over the last two decades, its concentration has more than doubled. Most of this has come from fossil fuels (especially coal), cattle, rice paddies, and waste dumps.  

Scientists have long been worried over the risk of a “methane bomb” — a rapid increase in the amount of methane released to the atmosphere — from thawing wetlands in Siberia’s permafrost. But now, a study by three German geologists is raising the alarm over increasing emissions from thawing rock formations as well. 

While the thawing wetlands release microbial methane from the decay of the soil and the organic matter, the thawing limestone releases hydrocarbons and gas hydrates from reservoirs below (and within) the permafrost. These emissions are “much more dangerous” than what was previously believed, according to the researchers.

“We observed an increase in methane concentration starting last summer. This remained over the winter, so there must have been a steady steady flow of methane from the ground,” Nikolaus Froitzheim, who led the research, told The Guardian. “At the moment, these anomalies are not of a very big magnitude, but it shows there is something going on.”

The researchers said they don’t know yet how dangerous these methane releases are, mainly because of a lack of information on how fast the gas is released.  

Climate-wise, things are already bad. But this could add even more fuel onto an already massive fire. That’s why the team calls on further research on the issue. If the planet’s temperature keeps growing, the release of additional methane could be the difference between catastrophe and apocalypse, they added. 

A satellite analysis

For the study, the researchers worked with satellite data to measure methane concentrations in the Taymyr Peninsula and its surroundings in northern Siberia, which was affected by the world’s most extreme heatwave of 2020. They focused on two “conspicuous elongates areas of limestone – stripes up to 375 miles long and several miles wide.  

There’s hardly any soil in the stripes, making the limestone crop out of the surface. As the rock formations warm up, they start to crack, releasing methane that was trapped inside. Concentrations of methane were elevated by about 5% during the heatwave. Additional tests showed the concentration remained as high in the spring of 2021 despite the return of low temperatures. 

“It’s intriguing. It’s not good news if it’s right,” Robert Max Holmes, a senior scientist at the Woodwell Climate Research Center, who was not involved in the study, told the Washington Post. “Nobody wants to see more potentially nasty feedbacks and this is potentially one. If something in the Arctic is going to keep me up at night that’s still what it is.”

The scientists now plan to investigate their findings further and model calculations to find out how much and how fast natural gas may be released. Froitzhem said the estimated amounts of natural gas in the subsurface of North Siberia are huge. Releasing the methane accumulated there to the atmosphere could have severe consequences on the global climate, he added.

The study was published in the journal PNAS.