A study suggests that the central-western Greenland Ice Sheet (GIS) is on the verge of a critical transition. The GIS is losing mass at an accelerating rate due to climate change and has been predicted to melt entirely by 3000 AD under the worst-case scenario, potentially raising global sea level by more than 7 meters. Niklas Boers and Martin Rypdal estimated the stability of the central-western GIS by analyzing summer sea-level temperatures from stations and melt rates from a stack of ice cores, reconstructing ice sheet height and using model simulations. The melt rate and ice sheet height fluctuations revealed early warning signals suggesting that this part of the ice sheet is approaching a critical transition. Additional results suggest that the physical process underlying the early warning signals is the melt-elevation feedback--a cycle in which melting decreases ice sheet height, thereby exposing the surface to warmer temperatures and further accelerating melting. The findings suggest that the melt-elevation feedback is the dominant mechanism driving the ongoing destabilization of the central-western GIS in response to rising temperatures. According to the authors, the results suggest that this portion of the ice sheet will undergo significantly enhanced melting in the near future, highlighting the need to determine the stability of the entire GIS.
Article #2020-24192: "Critical slowing down suggests that the western Greenland Ice Sheet is close to a tipping point," by Niklas Boers and Martin Rypdal
MEDIA CONTACT: Niklas Boers, Free University Berlin, Berlin, GERMANY; email: boers@pik-potsdam.de
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Proceedings of the National Academy of Sciences