Subsea permafrost carbon stocks and climate change sensitivity estimated by expert assessment

• Published in: Environmental Research Letters
• Main Authors: Sayedi, Sayedeh Sara, Abbott, Benjamin W, Thornton, Brett F, Frederick, Jennifer M, Vonk, Jorien E, Overduin, Paul, Schädel, Christina, Schuur, Edward A G, Bourbonnais, Annie, Demidov, Nikita, Gavrilov, Anatoly, He, Shengping, Hugelius, Gustaf, Jakobsson, Martin, Jones, Miriam C, Joung, DongJoo, Kraev, Gleb, Macdonald, Robie W, David McGuire, A, Mu, Cuicui, O’Regan, Matt, Schreiner, Kathryn M, Stranne, Christian, Pizhankova, Elena, Vasiliev, Alexander, Westermann, Sebastian, Zarnetske, Jay P, Zhang, Tingjun, Ghandehari, Mehran, Baeumler, Sarah, Brown, Brian C, Frei, Rebecca J
• Other Authors: Russian Science Foundation, Permafrost Carbon Network through the National Science Foundation (NSF) Study of Environmental Arctic Change, Swedish Science Foundation, National Science Foundation, National Key R&D Program of China, Brigham Young University
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: IOP Publishing 2020
• Subjects: Arctic; Arctic Ocean; Climate change; permafrost
• Online Access: http://dx.doi.org/10.1088/1748-9326/abcc29; https://iopscience.iop.org/article/10.1088/1748-9326/abcc29; https://iopscience.iop.org/article/10.1088/1748-9326/abcc29/pdf

Abstract The continental shelves of the Arctic Ocean and surrounding seas contain large stocks of organic matter (OM) and methane (CH 4 ), representing a potential ecosystem feedback to climate change not included in international climate agreements. We performed a structured expert assessment with 25 permafrost researchers to combine quantitative estimates of the stocks and sensitivity of organic carbon in the subsea permafrost domain (i.e. unglaciated portions of the continental shelves exposed during the last glacial period). Experts estimated that the subsea permafrost domain contains ∼560 gigatons carbon (GtC; 170–740, 90% confidence interval) in OM and 45 GtC (10–110) in CH 4 . Current fluxes of CH 4 and carbon dioxide (CO 2 ) to the water column were estimated at 18 (2–34) and 38 (13–110) megatons C yr −1 , respectively. Under Representative Concentration Pathway (RCP) RCP8.5, the subsea permafrost domain could release 43 Gt CO 2 -equivalent (CO 2 e) by 2100 (14–110) and 190 Gt CO 2 e by 2300 (45–590), with ∼30% fewer emissions under RCP2.6. The range of uncertainty demonstrates a serious knowledge gap but provides initial estimates of the magnitude and timing of the subsea permafrost climate feedback.