Ancient methane being released by Arctic melt

Scientists have reported finding thousands of sites in Greenland and Alaska where ancient methane gas is bubbling into the atmosphere, possibly with great ramifications for global warming. A team from the University of Alaska at Fairbanks (UAF) used ground and aerial surveys to identify around 150,000 locations of seepage at partially ice-covered Arctic lakes.

Much of the methane released was found to be several millennia old, having only been able to escape now as the ice sheet slowly melts. Other gases were found to be newer, possibly caused by decaying plant vegetation in the lakes’ warmer waters.

Katey Walter Anthony, who led the team, told the Nature Geoscience journal that their analysis of isotope ratios in the sampled methane molecules allowed them to date the gasses. She also said the findings could have an effect on future climate change predictions.

“We observed most of these cryosphere-cap seeps in lakes along the boundaries of permafrost thaw and in moraines and fjords of retreating glaciers,” the researchers wrote, adding that the gasses are being release due to global warming.

“If this relationship holds true for other regions where sedimentary basins are at present capped by permafrost, glaciers and ice sheets, such as northern West Siberia, rich in natural gas and partially underlain by thin permafrost predicted to degrade substantially by 2100, a very strong increase in methane carbon cycling will result, with potential implications for climate warming feedbacks.”

After holding steady for a few years, the concentration of methane in the Arctic atmosphere has begun to rise again, with several countries dispatching missions to the area to monitor the situation.

“The Arctic is the fastest warming region on the planet, and has many methane sources that will increase as the temperature rises,” Prof Euan Nisbet, who is involved in Arctic methane research, told the BBC. “This is yet another serious concern: the warming will feed the warming.”

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