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

• Published in: Environmental Research Letters
• Main Authors: Sayedeh Sara Sayedi, Benjamin W Abbott, Brett F Thornton, Jennifer M Frederick, Jorien E Vonk, Paul Overduin, Christina Schädel, Edward A G Schuur, Annie Bourbonnais, Nikita Demidov, Anatoly Gavrilov, Shengping He, Gustaf Hugelius, Martin Jakobsson, Miriam C Jones, DongJoo Joung, Gleb Kraev, Robie W Macdonald, A David McGuire, Cuicui Mu, Matt O’Regan, Kathryn M Schreiner, Christian Stranne, Elena Pizhankova, Alexander Vasiliev, Sebastian Westermann, Jay P Zarnetske, Tingjun Zhang, Mehran Ghandehari, Sarah Baeumler, Brian C Brown, Rebecca J Frei
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2020
• Subjects: subsea permafrost; carbon stocks; climate change; expert assessment; Environmental technology. Sanitary engineering; TD1-1066; Environmental sciences; GE1-350; Science; Q; Physics; QC1-999; Arctic; Arctic Ocean; Climate change; permafrost
• Online Access: https://doi.org/10.1088/1748-9326/abcc29; https://doaj.org/article/01108997f4c14a3cb2c3d4e1b078268f

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.