(a) Observed SIC from the National Snow and Ice Data Center (NSIDC) Bootstrap algorithm, (b) CMIP5 multi-model mean SIC, (c) observed SST from Hadley Centre Sea Ice and Sea Surface Temperature (HadISST) and (d) CMIP5 multi-model mean SST. Trends are expressed as a change per degree of global warming (°C−1 GW). Multi-model means are calculated using the first available ensemble member for each model. Stippling indicates significance: (a,c) above the 95% level as determined by a two-sided Student’s t-test and (b,d) where 80% of models agree on the sign of the mean trend33, which corresponds to 33 out of 41 models. The mean-state 15% SIC contour is shown in black. In (a) AS, Amundsen Sea; BS, Bellingshausen Sea; RS, Ross Sea; WS,Weddell Sea.