Increasing mass loss from Greenland's Mittivakkat Gletscher

摘要

Warming in the Arctic during the past several decades has caused glaciers tothin and retreat, and recent mass loss from the Greenland Ice Sheet is welldocumented. Local glaciers peripheral to the ice sheet are also retreating,but few mass-balance observations are available to quantify that retreat anddetermine the extent to which these glaciers are out of equilibrium withpresent-day climate. Here, we document record mass loss in 2009/10 for theMittivakkat Gletscher (henceforth MG), the only local glacier in Greenlandfor which there exist long-term observations of both the surface massbalance and glacier front fluctuations. We attribute this mass lossprimarily to record high mean summer (June–August) temperatures incombination with lower-than-average winter precipitation. Also, we use the15-yr mass-balance record to estimate present-day and equilibriumaccumulation-area ratios for the MG. We show that the glacier issignificantly out of balance and will likely lose at least 70% of itscurrent area and 80% of its volume even in the absence of further climatechanges. Temperature records from coastal stations in Southeast Greenlandsuggest that recent MG mass losses are not merely a local phenomenon, butare indicative of glacier changes in the broader region. Mass-balanceobservations for the MG therefore provide unique documentation of thegeneral retreat of Southeast Greenland's local glaciers under ongoingclimate warming.