Wind-driven trends in Antarctic sea-ice drift

The sea-ice cover around Antarctica has experienced a slight expansion in area over the past decades(1,2). This small overall increase is the sum of much larger opposing trends in different sectors that have been proposed to result from changes in atmospheric temperature or wind stress(3-5), precipitation(6,7), ocean temperature(8), and atmosphere or ocean feedbacks(9,10). However, climate models have failed to reproduce the overall increase in sea ice(11). Here we present a data set of satellite-tracked sea-ice motion for the period of 1992-2010 that reveals large and statistically significant trends in Antarctic ice drift, which, in most sectors, can be linked to local winds. We quantify dynamic and thermodynamic processes in the internal ice pack and show that wind-driven changes in ice advection are the dominant driver of ice-concentration trends around much of West Antarctica, whereas wind-driven thermodynamic changes dominate elsewhere. The ice-drift trends also imply large changes in the surface stress that drives the Antarctic ocean gyres, and in the fluxes of heat and salt responsible for the production of Antarctic bottom and intermediate waters.