Study: Arctic Marine Sediment Shows Evidence Of Rapid, Massive Carbon Flows From Melting Permafrost
A dive deep into 27,000 years worth of muck piled up on the bottom of the Arctic Ocean has spurred researchers to renew warnings about a potential surge of greenhouse gas emissions from thawing permafrost. By tracking chemical and organic fingerprints in long-buried layers of sediments remaining from previously frozen ground, the scientists showed that ancient phases of rapid warming in the Arctic, such as occurred near the end of the last ice age, released carbon on a massive scale. Vast frozen landscapes collapsed, turned to mud and flowed into the sea, releasing carbon dioxide and methane into the atmosphere along the way.
The study, published today in Science Advances, shows that only a few degrees of warming in the Arctic is enough "to abruptly activate large-scale permafrost thawing," suggesting a "sensitive trigger" for greenhouse gas emissions from thawing permafrost. The results also support climate models that have shown "large injections of CO2 into the atmosphere" when glaciers, and the frozen lands beneath them, melted.
The vast permafrost regions of the Arctic hold more carbon than the Earth's atmosphere, and a rapid and a large release of CO2 that exceeds current projections would dangerously accelerate global warming. Understanding how that happened in the past helps researchers make more accurate projections for the future. In the Northern Hemisphere, permafrost spreads over about 9 million square miles—in total, an area nearly as big as the United States, China and Canada combined.
One of the three warming phases the researchers studied was about 14,700 years ago, when temperatures in the Arctic suddenly warmed by 1.8 degrees Fahrenheit, said lead author Jannik Martens, an Arctic researcher with the University of Stockholm. It was such a distinct climate disruption that scientists named it the Bölling-Alleröd warming for two sites where distinctive soil layers show the ancient warming.
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https://insideclimatenews.org/news/16102020/permafrost-study-arctic-ocean-climate-change