Influence of seafloor morphology on the retreat of Northern Greenland outlet glaciers under climate warming

Sammanfattning

In our warming climate, driven by human activity and greenhouse gas emissions, the Greenland ice sheet is shrinking in extent. One of the ways in which the Greenland ice sheet loses mass is through its interaction with warm water at its outlet glaciers. The three adjacent fjords: Petermann fjord, Sherard Osborn fjord, and Victoria fjord, are marine terminating glacial fjords, where the Greenland ice sheet meets the ocean. Comparing the three adjacent fjords, there is noticeable difference in how much of their respective floating ice tongues remain. One of the factors behind this variation is the differences in seafloor geomorphology of the fjords, which controls the inflow of warm water into the fjords. The aim of this study is the comparison of seafloor geomorphology within the fjords in relation to their respective ice masses. Bathymetric data acquired by multibeam echo-sounding from multiple Greenland expeditions were used for the morphological mapping done in QGIS. The study results show varied seafloor landforms throughout the three fjords, with more sedimentary landforms such as grounding-zone wedges and moraines present in the Petermann and Sherard Osborn fjords, and Victoria fjord instead dominated by rough bedrock structures. A possible interpretation of the results is that the presence of sedimentary landforms formed at longer standstills during past ice retreat episodes act as barriers against warm water inflow, keeping the floating ice tongues from collapsing. In our continuously warming climate, deepening the knowledge on ice-ocean interaction and ice sheet melting is of critical importance. This study aims to contribute some new insights to that area.