High Arctic wetting reduces permafrost carbon feedbacks to climate warming

• Published in: Nature Climate Change
• Main Authors: Lupascu, Massimo, Welker, Jeff M., Seibt, Ulrike, Maseyk, Kadmiel, Xu, Xiaomei, Czimczik, Claudia I.
• Other Authors: Department of Earth System Science Irvine (ESS), University of California Irvine (UCI), University of California-University of California, University of Alaska Southeast (UAS), Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), University of California Los Angeles (UCLA), University of California, US National Science Foundation ARC-0909514, ARC-0909538, European Research Council (ERC) 202835
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDV]Life Sciences [q-bio]; [SDE]Environmental Sciences; Arctic; Greenland; Climate change; Global warming; Ice; permafrost; Sea ice; Tundra
• Online Access: https://hal.inrae.fr/hal-02641366; https://doi.org/10.1038/NCLIMATE2058

International audience The carbon (C) balance of permafrost regions is predicted to be extremely sensitive to climatic changes(1-3). Major uncertainties exist in the rate of permafrost thaw and associated C emissions (33-508 Pg C or 0.04-1.69 degrees C by 2100; refs 2,3) and plant C uptake. In the High Arctic, semi-deserts retain unique soil-plant-permafrost interactions(4,5) and heterogeneous soil C pools(6) (>12 Pg C; ref. 7). Owing to its coastal proximity, marked changes are expected for High Arctic tundra(8). With declining summer sea-ice cover(9), these systems are simultaneously exposed to rising temperatures(9), increases in precipitation(10) and permafrost degradation(11). Here we show, using measurements of tundra-atmosphere C fluxes and soil C sources (C-14) at a long-term climate change experiment in northwest Greenland, that warming decreased the summer CO2 sink strength of semi-deserts by up to 55%. In contrast, warming combined with wetting increased the CO2 sink strength by an order of magnitude. Further, wetting while relocating recently assimilated plant C into the deep soil decreased old C loss compared with the warming-only treatment. Consequently, the High Arctic has the potential to remain a strong C sink even as the rest of the permafrost region transitions to a net C source as a result of future global warming.