LAUSR

Overall Antarctic sea ice extent in the 2016 spring attained a record minimum for the satellite period (1979–2016), presenting an abrupt departure from the record maxima in previous years and the slight upward trend since 1979. In 2016 the atmospheric conditions over the Southern Ocean changed dramatically from the prevailing cold and westerly anomalies in summer to warm and easterly anomalies in spring. We conducted numerical experiments with an ocean-sea ice model to quantify the major factors responsible for the unanticipated change in 2016. Our model successfully reproduces the long-term increasing trend and the 2016 minimum, and the numerical experiments suggest that the 2016 minimum event is largely attributable to thermodynamic surface forcing (53%), while wind stress and the sea-ice and oceanic conditions from the previous summer (January 2016) explain the remaining 34% and 13%, respectively. This confirms that it is essential to assess the thermal conditions in both the atmosphere and ocean when estimating Antarctic sea ice fields to future climate changes.