Access of Atlantic Water to East Greenland glaciers

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The Greenland Ice Sheet is losing mass at an accelerating rate, making it today one of the largest contributors to global sea level rise. Warming subsurface (intermediate) ocean waters of Atlantic origin interacting with marine terminating glaciers within fjords around Greenland are regarded an import driver of the retreating ice sheet. During the first phase of SPP ”Regional Sea Level Chance and Society” within our project OGreen79 we able to show based on successful in situ observations on the shelf of Northeast Greenland, that the floating ice tongue of the 79-North Glacier (79NG) is exposed all-year-round to a swift inflow of warm Atlantic Intermediate Water (AIW). Surprisingly, the inflow into the ice shelf cavity is hydraulically controlled by a topographic sill right at the glacier calving front, which was discovered during one of our expeditions. We also demonstrated that the dramatic, ongoing thinning of the ice tongue of the 79NG by 90 m on decadal time scales has been driven by AIW warming. In this follow-up proposal, A2Green, we follow up on the important findings made during the first phase. We now widen the view to investigate ocean-glacier interaction on a regional rather than a local scale. We propose to extend our investigations to the entire East Greenland shelf north of Denmark Strait where the presence of subsurface AIW - interacting with numerous marine terminating glaciers - represents a ubiquitous feature. What makes the area unique, is that the AIW found on the shelf is mainly supplied be a single source, namely the recirculation of Atlantic Water in Fram Strait. Overall, three objectives will be pursued, relevant for the understanding of ocean-ice sheet interaction. We will investigate i. the multiannual large-scale ocean connections of the AIW present on the East Greenland continental shelf, ii. the role of shelf and shelf edge processes for AIW variability on the continental shelf, and iii. near-coastal, topographic control on time variable AIW inflows toward two different ocean-glacier systems. The 79NG - being located relatively close to the recirculation in Fram Strait - will remain an important focus. In addition, Scoresby Sound -located away from Fram Strait near the southern boundary of our work domain - will represent a new focus. One of the largest East Greenland glaciers, the Daugaard Jensen Glacier, terminates into the Scoresby Sound fjord system. The investigations will be achieved by analyzing both historical and active mooring time series in Fram Strait and on the shelf of East Greenland together with hydrographic data sets. High resolution simulation relying on an ocean-sea ice general circulation model will be applied to put the results into a larger spatial and temporal context.