Thinning and volume loss of the Arctic Ocean sea ice cover: 2003–2008

We present our best estimate of the thickness and volume of the Arctic Ocean ice cover from 10 Ice, Cloud, and land Elevation Satellite (ICESat) campaigns that span a 5‐year period between 2003 and 2008. Derived ice drafts are consistently within 0.5 m of those from a submarine cruise in mid‐November of 2005 and 4 years of ice draft profiles from moorings in the Chukchi and Beaufort seas. Along with a more than 42% decrease in multiyear (MY) ice coverage since 2005, there was a remarkable thinning of ∼0.6 m in MY ice thickness over 4 years. In contrast, the average thickness of the seasonal ice in midwinter (∼2 m), which covered more than two‐thirds of the Arctic Ocean in 2007, exhibited a negligible trend.…