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A 2700-year Record of Permafrost Thaw Sensitivity to Climate

Changes in the 14C ages of carbon and biomarkers deposited at the mouth of a river draining a permafrost watershed track responses of regional thaw depth to past warming and cooling.

Source: AGU Advances


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With amplified warming of the Arctic, there is increasing concern about thawing of permafrost and the fate of the large amounts of organic material it contains. Zhang et al. [2021] report a 2700-year record of variations in the radiocarbon age of carbon in bulk organic matter and plant waxes originating from a the Alaskan Colville river, a watershed underlain by continuous permafrost.

Pre-depositional ages for bulk C ranged from about 1000 to 4300 years, while isolated plant waxes were even older, indicating that erosion was the major contributor to deposited organic matter. During colder periods, pre-depositional ages of plant waxes were about 930 years younger than during warmer periods before and after, suggesting shallower depths of seasonal thaw in cooler periods, and deepening in warmer periods.  Over the past century, the age of deposited carbon has increased, providing evidence supporting increased thaw depths, and therefore also presumably C export, with current global warming.

Citation: Zhang, X., Bianchi, T., Hanna, A. et al. [2021]. Recent Warming Fuels Increased Organic Carbon Export from Arctic Permafrost. AGU Advances, 2, e2021AV000396. https://doi.org/10.1029/2021AV000396

—Susan Trumbore, Editor-in-Chief, AGU Advances

Text © 2021. The authors. CC BY-NC-ND 3.0
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