Proc. Natl Acad. Sci. USA 116, 1934–1939 (2019).

The warming of both the ocean and the atmosphere is causing loss of the Greenland Ice Sheet through surface melt and iceberg calving. How each of these contribute to the loss-rate and regional effects was investigated by Michael Bevis, of Ohio State University, and co-authors.

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Elijah Lovkoff/Alamy Stock Photo

They combine remotely sensed data from the Gravity Recovery and Climate Experiment (GRACE) mission and the Greenland GPS Network with regional climate simulations. In 2003, the Greenland Ice sheet was losing ~102 Gt of ice per year. Over the following ten years this has accelerated progressively to ~393 Gt per year. While large losses were seen for the southeast and northwest, where there are numerous marine-terminating glaciers, the southwest — a smaller contributor and a region with few marine-terminating glaciers — saw the largest sustained acceleration. This acceleration tracks the North Atlantic Oscillation, which in its negative phase increases summer warming and incoming radiation, whilst decreasing snowfall; resulting in increased surface melt and loss.

The acceleration and subsequent deceleration, in 2013–2014, is attributed to atmospheric forcing (air temperature and incoming radiation) — highlighting the potential of future loss from southwest Greenland.