High Arctic wetting reduces permafrost carbon feedbacks to climate warming

Lupascu, M.; Welker, J. M.; Seibt, U.; Maseyk, K.; Xu, X. and Czimczik, C. I. (2014). High Arctic wetting reduces permafrost carbon feedbacks to climate warming. Nature Climate Change, 4(1) pp. 51–55.

DOI: https://doi.org/10.1038/NCLIMATE2058

Abstract

The carbon (C) balance of permafrost regions is predicted to be extremely sensitive to climatic changes. Major uncertainties exist in the rate of permafrost thaw and associated C emissions (33–508 Pg C or 0.04–1.69 °C by 2100) and plant C uptake. In the High Arctic, semi-deserts retain unique soil–plant–permafrost interactions and heterogeneous soil C pools (>12 Pg C). Owing to its coastal proximity, marked changes are expected for High Arctic tundra. With declining summer sea-ice cover, these systems are simultaneously exposed to rising temperatures, increases in precipitation and permafrost degradation. Here we show, using measurements of tundra–atmosphere C fluxes and soil C sources (C) 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.

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