On the Influence of the NAO on Outlet Glacier Stability in SE Greenland during the Past 100 Years

Abstract:

The Greenland Ice sheet has gained massive attention in recent years due to a sudden increase in mass loss at the onset of this century. A significant part of this mass loss has been attributed to increased ice discharge at the margin through iceberg calving from marine-terminating outlet glaciers. However, due to the lack of instrumental data beyond the past 20-30 years it is difficult to evaluate if this was an outstanding event or if it was part of a recurring phenomenon acting on inter-annual, inter-decadal or centennial timescales. In order to improve understanding of the timescales involved in glacier changes and on the influence of ocean and atmosphere variability we investigate sediment archives from fjords with marine terminating glaciers. Near the glacier margin the sedimentation rates are relatively high due to glacial flour input and rafting of iceberg debris. Our studies of several sediment cores obtained from Sermilik Fjord by Helheim Glacier in Southeast Greenland has allowed us to reconstruct glacier calving, shelf temperature and fjord water renewal rate for the past 100 years. These studies show that dominant modes of climate variability, i.e. the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation, affect ocean properties near the glacier and that the recorded variability concurs with reconstructed outlet glacier changes. This presentation provides an overview these studies.