Barents Sea ice cover reflects Atlantic inflow

Abstract

The recent Arctic winter sea-ice retreat is most pronounced in the Barents Sea. Using available observations of the Atlantic inflow to the Barents Sea and results from a regional ice-ocean model we assess the role of inflowing heat anomalies on sea-ice variability. Between 1979 and 2008 the reduction of annual sea-ice area was 15% decade−1, and in the eastern Barents Sea the winter ice edge retreated about 240 km. The interannual variability and decrease in sea-ice area reflects observed variability in the Atlantic inflow. The heat budget of the model is used to elucidate further how Atlantic inflow anomalies influence the sea-ice area. It is argued that ocean heat transport into the western Barents Sea sets the boundary of the ice-free Atlantic domain and, hence, the sea-ice extent. The regional heat content and heat loss to the atmosphere scales with the area of open ocean as a consequence. Recent sea-ice loss is thus largely caused by an increasing ”Atlantification” of the Barents Sea. A simple prognostic model based on this scaling – and the Atlantic heat source – explains 58% of the variance in sea-ice area.