Satellite records show a decline in ice extent over more than three decades, with a record minimum in September 2012. Results from the Pan‐Arctic Ice‐Ocean Modelling and Assimilation system (PIOMAS) suggest that the decline in extent has been accompanied by a decline in volume, but this has not been confirmed by data. Using new data from the European Space Agency CryoSat‐2 (CS‐2) mission, validated with in situ data, we generate estimates of ice volume for the winters of 2010/11 and 2011/12. We compare these data with current estimates from PIOMAS and earlier (2003–8) estimates from the National Aeronautics and Space Administration ICESat mission. Between the ICESat and CryoSat‐2 periods, the autumn volume declined by 4291 km3 and the winter volume by 1479 km3. This exceeds the decline in ice volume in the central Arctic from the PIOMAS model of 2644 km3 in the autumn, but is less than the 2091 km3 in winter, between the two time periods.

Figure 1| Arctic Ocean mean sea surface and trends in sea surface height and the wind field curl (1995-2010). a, Arctic Ocean mean sea surface: Constructed from 15 years of satellite radar altimetry data and calculated with respect to the EGM08 geoid. The Beaufort Gyre is the yellow/orange dome in the Western Arctic. b, Trend in sea surface height calculated from satellite radar altimetry. c, Trend in the wind field curl calculated from NCEP/NCAR Reanalysis data.

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