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Arctic Ocean sediments reveal permafrost thawing during past climate warming

Arctic Ocean sediments reveal permafrost thawing during past climate warming
Science
Sea floor sediments of the Arctic Ocean can help scientists understand how permafrost responds to climate warming. A multidisciplinary team from Stockholm University has found evidence of past permafrost thawing during climate warming events at the end of the last ice age. Their findings, published in Science Advances, caution about what could happen in the near future: That Arctic warming by only a few degrees Celsius may trigger massive permafrost thawing, coastal erosion, and the release of the greenhouse gases carbon dioxide (CO2) and methane (CH4) into the atmosphere.

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Arctic permafrost stores more carbon than the atmosphere does. When permafrost thaws, this carbon may be converted to greenhouse gases (CO2 and CH4) that then enter the atmosphere and may affect the climate system. To improve predictions of future greenhouse gas emissions from permafrost, scientists have started to look into the past, exploring how previous climate warming, for example at the end of the last ice age, affected permafrost and its vast pool of carbon.

In the current study, the scientists used an eight meters long sediment core that was recovered from the sea floor more than 1,000 meters below the surface of the Arctic Ocean during the SWERUS-C3 expedition onboard the Swedish icebreaker Oden back in 2014. To reconstruct permafrost thawing on land, the scientists applied radiocarbon (14C) dating and molecular analysis to trace organic remains that once were released by thawing permafrost and then washed into the Arctic Ocean.

Gustafsson, Martens and their colleagues are now again in the Arctic Ocean as part of the International Siberian Shelf Study (ISSS-2020) onboard the Russian research vessel Akademik Keldysh. The expedition left the port of Arkhangelsk on September 26 and is currently in the East Siberian Sea, seeking more answers to how changing climate may trigger release of carbon, including greenhouse gases, from Arctic permafrost systems, including coastal erosion and permafrost below the sea bottom preserved from the past ice age.

Materials provided by Stockholm University . Note: Content may be edited for style and length.

Stockholm University. "Arctic Ocean sediments reveal permafrost thawing during past climate warming." ScienceDaily. ScienceDaily, 16 October 2020. .

Stockholm University. "Arctic Ocean sediments reveal permafrost thawing during past climate warming." ScienceDaily. www.sciencedaily.com/releases/2020/10/201016143056.htm (accessed October 17, 2020).

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Sep. 10, 2018 — The loss of arctic permafrost deposits by coastal erosion could amplify climate warming via the greenhouse effect. A study using sediment samples from the Sea of Okhotsk on the eastern coast of ...

Aug. 16, 2018 — Methane released by thawing permafrost from some Arctic lakes could significantly accelerate climate change, according to a new study. Unlike shallow, gradual thawing of terrestrial permafrost, the ...

Nov. 21, 2016 — The Arctic is warming rapidly, with projected temperature increases larger than anywhere else in the world. The Arctic regions are particularly important with respect to climate change, as permafrost ...

June 16, 2016 — Permafrost below shallow Arctic lakes is thawing as a result of changing winter climate, new research shows. These rates of warming are similar to those observed in terrestrial permafrost, yet those ...
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