Peak refreezing in the Greenland firn layer under future warming scenarios.

• Published in: Nature Communications
• Main Authors: Noël, Brice, Lenaerts, Jan T M, Lipscomb, William H, Thayer-Calder, Katherine, van den Broeke, Michiel R
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Research 2022
• Subjects: Chemistry (all); Biochemistry; Genetics and Molecular Biology (all); Multidisciplinary; Physics and Astronomy (all); General Physics and Astronomy; General Biochemistry; Genetics and Molecular Biology; General Chemistry; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Greenland; Ice Sheet
• Online Access: https://orbi.uliege.be/handle/2268/302202; https://orbi.uliege.be/bitstream/2268/302202/1/Noel_2022_Ncomms.pdf; https://doi.org/10.1038/s41467-022-34524-x

peer reviewed Firn (compressed snow) covers approximately 90% of the Greenland ice sheet (GrIS) and currently retains about half of rain and meltwater through refreezing, reducing runoff and subsequent mass loss. The loss of firn could mark a tipping point for sustained GrIS mass loss, since decades to centuries of cold summers would be required to rebuild the firn buffer. Here we estimate the warming required for GrIS firn to reach peak refreezing, using 51 climate simulations statistically downscaled to 1 km resolution, that project the long-term firn layer evolution under multiple emission scenarios (1850-2300). We predict that refreezing stabilises under low warming scenarios, whereas under extreme warming, refreezing could peak and permanently decline starting in southwest Greenland by 2100, and further expanding GrIS-wide in the early 22nd century. After passing this peak, the GrIS contribution to global sea level rise would increase over twenty-fold compared to the last three decades.