Jun 28, 2017

Decreasing cloud cover drives the recent mass loss on the Greenland Ice Sheet

by
Stefan Hofer, Andrew J. Tedstone, Xavier Fettweis, Jonathan L. Bamber
,
Science Advances
  • States that the Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate since the mid-1990s
  • States that this has been due to both increased ice discharge into the ocean and melting at the surface, with the latter being the dominant contribution
  • States that this change in state has been attributed to rising temperatures and a decrease in surface albedo
  • Shows, using satellite data and climate model output, that the abrupt reduction in surface mass balance since about 1995 can be attributed largely to a coincident trend of decreasing summer cloud cover enhancing the melt-albedo feedback
  • Satellite observations show that, from 1995 to 2009, summer cloud cover decreased by 0.9 ± 0.3% per year
  • Model output indicates that the GrIS summer melt increases by 27 ± 13 gigatons (Gt) per percent reduction in summer cloud cover, principally because of the impact of increased shortwave radiation over the low albedo ablation zone
  • Finds that the observed reduction in cloud cover is strongly correlated with a state shift in the North Atlantic Oscillation promoting anticyclonic conditions in summer and suggests that the enhanced surface mass loss from the GrIS is driven by synoptic-scale changes in Arctic-wide atmospheric circulation