This award will support a study of glacier-fjord interactions in east Greenland. The 'Intellectual Merit' of the proposed study lies in the current understanding that the contribution of the Greenland Ice Sheet to sea level rise more than doubled in the last seven years, mostly because of a widespread and nearly simultaneous acceleration of many glaciers that terminate at tidewater in deep fjords. Understanding the causes of changes in glacier dynamics, and predicting their future trajectories is a topic of enormous scientific and societal importance. The Greenland fjords provide an intimate connection between the ice sheet and the ocean and, in turn, raise the possibility that the observed warming of the ocean around southeast and western Greenland was the trigger for recent changes in outlet glacier dynamics.
A pilot study conducted by the PIs in east Greenland, and a separate study in west Greenland, found warm ocean waters in the proximity of Helheim Glacier and Jakobshavn Isbræ, respectively, supporting the hypothesis that their acceleration was triggered by ocean warming. While intriguing, the presence of warm waters in Greenland's fjords alone is not enough to conclude that the ocean is modulating glacier dynamics. A test of this hypothesis requires a more detailed understanding of glacier/fjord interactions than is possible with the limited amount of data currently available. This study will fill this gap by investigating glacier-ocean interactions in a typical glacier-fjord system in East Greenland (Sermilik Fjord and Helheim Glacier) through an intensive two-year field program. Through summer surveys and year-round moored instruments, the circulation and properties of the fjord on tidal to yearly time-scales will be mapped, and the liquid fresh water flux out of the fjord will be quantified. A collaboration with Greenlandic marine biologists will allow important ocean data in the region outside the fjord to be obtained using tagged seals. GPS methods and remote sensing will allow changes in the flow behavior of Helheim Glacier to be examined in the context of changing fjord circulation. Satellite remote sensing and field tracking of large icebergs will provide estimates of the solid export of fresh water and its variability.
The proposed study has numerous 'Broader Impacts'. The are likely to be a significant component of next-generation ice sheet models seeking to predict the evolution of the Greenland Ice Sheet and future rates of sea level rise. The project brings together an inter-disciplinary group of investigators, involves two junior scientists embarking on their careers, and initiates an international collaboration with Greenlandic scientists. A graduate student will be trained in glaciology and physical oceanography, contributing to society's need for experts in the area of ice sheet-ocean interactions. The fieldwork utilizes local vessels and relies strongly on the knowledge of generations of local hunters who have navigated Sermilik Fjord, thus fostering a two-way exchange between the local community and foreign scientists. A non-technical report summarizing the findings of ocean-glacier measurements will distributed in the local community, which is vulnerable to rapid environmental changes affecting its primary natural resource.
