Dependence of the evolution of carbon dynamics in the northern permafrost region on the trajectory of climate change

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 115; no. 15; pp. 3882 - 3887
• Main Authors: McGuire, A. David, Lawrence, David M., Koven, Charles, Clein, Joy S., Burke, Eleanor, Chen, Guangsheng, Jafarov, Elchin, MacDougall, Andrew H., Marchenko, Sergey, Nicolsky, Dmitry, Peng, Shushi, Rinke, Annette, Ciais, Philippe, Gouttevin, Isabelle, Hayes, Daniel J., Ji, Duoying, Krinner, Gerhard, Moore, John C., Romanovsky, Vladimir, Schädel, Christina, Schaefer, Kevin, Schuur, Edward A. G., Zhuang, Qianlai
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 10.04.2018; National Academy of Sciences, Washington, DC (United States)
• Subjects: Biological Sciences; Carbon; Carbon sequestration; Climate change; Climate models; Computer simulation; Continental interfaces, environment; Dependence; Earth Sciences; Ecosystems; Environment models; Environmental changes; ENVIRONMENTAL SCIENCES; Feedback; Ocean, Atmosphere; Permafrost; permafrost carbon feedback; Projection; Sciences of the Universe; Vegetation; climate system; permafrost dynamics; carbon dynamics; permafrost carbon–climate feedback; soil carbon
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1719903115

We conducted a model-based assessment of changes in permafrost area and carbon storage for simulations driven by RCP4.5 and RCP8.5 projections between 2010 and 2299 for the northern permafrost region. All models simulating carbon represented soil with depth, a critical structural feature needed to represent the permafrost carbon–climate feedback, but that is not a universal feature of all climate models. Between 2010 and 2299, simulations indicated losses of permafrost between 3 and 5 million km² for the RCP4.5 climate and between 6 and 16 million km² for the RCP8.5 climate. For the RCP4.5 projection, cumulative change in soil carbon varied between 66-Pg C (1015-g carbon) loss to 70-Pg C gain. For the RCP8.5 projection, losses in soil carbon varied between 74 and 652 Pg C (mean loss, 341 Pg C). For the RCP4.5 projection, gains in vegetation carbon were largely responsible for the overall projected net gains in ecosystem carbon by 2299 (8- to 244-Pg C gains). In contrast, for the RCP8.5 projection, gains in vegetation carbon were not great enough to compensate for the losses of carbon projected by four of the five models; changes in ecosystem carbon ranged from a 641-Pg C loss to a 167-Pg C gain (mean, 208-Pg C loss). The models indicate that substantial net losses of ecosystem carbon would not occur until after 2100. This assessment suggests that effective mitigation efforts during the remainder of this century could attenuate the negative consequences of the permafrost carbon–climate feedback.