Abstract
Abstract
The Milne Ice Shelf was, until recently, a relatively stable ice shelf on the north coast of Ellesmere Island. In summer 2020, it underwent a major calving event, losing 43% of its surface area from its northern, ocean edge. A mass balance network across the ice shelf indicates that this calving was preceded by a mean annual surface mass balance of −0.40 ± 0.13 m water equivalent from 2008 to 2019, but with large inland-to-ocean variability. Individual stake measurements indicate that ablation is highest at the rear of the ice shelf, furthest from the ocean, while summer air temperature and shortwave radiation are lower towards the front of the ice shelf, where snow accumulation is greatest. The ice shelf shifts to a state of strongly negative mass balance in years with >200 cumulative positive degree-days, which occurred half the time over the study period. The mass balance gradient may help explain the 2020 calving pattern, as sustained thinning and fracture near the rear of the ice shelf may have reduced structural integrity, weakening the mechanical connection to the seaward section prior to its detachment.