Rapid decline of total Antarctic sea ice extent during 2014–16 controlled by wind-driven sea ice drift

Between 2014 and 2016 the annual mean total extent of Antarctic sea ice decreased by a record, unprecedented amount of 1.6 3 106 km2, the largest in a record starting in the late 1970s. The mechanisms behind such a rapid decrease remain unknown. Using the outputs of a high-resolution, global ocean–sea ice model we show that the change was predominantly a result of record atmospheric low pressure systems over sectors of the Southern Ocean in 2016, with the associated winds inducing strong sea ice drift. Regions of large positive and negative sea ice extent anomaly were generated by both thermal and dynamic effects of the wind anomalies. Although the strong wind forcing also generated the warmest ocean surface state from April to December 2016, we show that enhanced northward sea ice drift and hence increased melting at lower latitudes driven by strong winds made the dominant contribution to the large decrease in total Antarctic sea ice extent between 2014 and 2016.