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Thawing Arctic peatlands could release potent greenhouse gas

Tarmo Virtanen, University of Helsinki

Scientists have long predicted that rapidly warming temperatures in the Arctic could unleash huge amounts of carbon trapped beneath the permafrost. It's one of the tipping points in Earth's climate system that scientists are tracking closely. Now, researchers say thawing in the Arctic could also release significant amounts of nitrous oxide, an even more powerful greenhouse gas trapped below the permafrost, a new study finds.

Why it matters: Nitrous oxide is about 300 times more effective at trapping heat than carbon dioxide. But, despite the fact that more than 67 billion tons of nitrogen are stored in the Arctic permafrost, nearly all of the research on the impacts in the Arctic have focused on carbon releases. Vegetation and water can decrease the amount of nitrous oxide released to varying degrees, but this new study shows that up to a quarter of the Arctic could see significant releases of the gas along with carbon dioxide.

How they did it: Finnish scientists collected 16 samples of peat from Finland's Lapland region and slowly warmed them from underneath to simulate thawing in the lab.

The results: There was a fivefold increase in nitrous oxide emissions from samples of bare peat compared to the amount released when only the surface thaws, which happens seasonally. When plants or lichen were growing on top of a sample, emissions decreased by 90% and they were entirely suppressed in wet samples.