High Arctic wetting reduces permafrost carbon feedbacks to climate warming

• Published in: Nature climate change 2014-01, Vol.4 (1), p.51-55
• Main Authors: Lupascu, M., Welker, J. M., Seibt, U., Maseyk, K., Xu, X., Czimczik, C. I.
• Format: Article
• Language: English
• Subjects: 704/106/47; Carbon dioxide; Climate Change; Climate Change/Climate Change Impacts; Climatology. Bioclimatology. Climate change; Desert plants; Earth, ocean, space; Environment; Environmental Law/Policy/Ecojustice; Environmental Sciences; Exact sciences and technology; External geophysics; Global warming; Ice cover; letter; Life Sciences; Marine; Meteorology; Permafrost; Sea ice; Soil degradation; Tundra
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/nclimate2058

The combination of climatic warming and wetting can increase the CO 2 sink strength of High Arctic semi-deserts by an order of magnitude, according to a long-term climate manipulation experiment in northwest Greenland. These findings indicate that parts of the High Arctic have the potential to remain a strong carbon sink under future global warming. The carbon (C) balance of permafrost regions is predicted to be extremely sensitive to climatic changes 1 , 2 , 3 . 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; 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 ( 14 C) at a long-term climate change experiment in northwest Greenland, that warming decreased the summer CO 2 sink strength of semi-deserts by up to 55%. In contrast, warming combined with wetting increased the CO 2 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.