Several Firn Core Records of Accumulation over the Past Two Millennia in Dronning Maud Land, East Antarctica

Abstract:

With more than 50 meters sea-level equivalent stored as ice, the East Antarctic Ice Sheet (EAIS) has the potential to substantially contribute to global sea level. Current estimates and future projections of the EAIS contribution to sea-level rise have errors much greater than the magnitude, indicating the sign of its contribution remains under debate. The low magnitude and high interannual variability in the accumulation rate, coupled with relatively short and few accumulation records, generates a large portion of the uncertainty. Here, we present annually resolved accumulation records from two near-coastal and two interior firn cores from Dronning Maud Land. In addition, three multi-decadal records derived from volcanic chronologies provide coarser records from three sites along the western side of the plateau divide. Most of the firn cores were collected along the Norwegian-US IPY traverse in 2007 and 2008, and the records range between 393 and 2,195 years in length, five of which are more than 1,000 years long.

Our results provide a valuable dataset to investigate the periods of significant accumulation changes through the past hundreds to thousands of years, and provide a long-term reference period with which to compare the recent accumulation rates. Interestingly, the sign and magnitude of the relative difference in accumulation between the recent and long-term rates varies by location. We combine the records presented with other published firn core records from the region to investigate the spatial pattern of recent changes in the accumulation rate. Finally, the impact of the recent changes in accumulation rates observed in the records on ice-sheet mass balance is discussed both in terms of the input-output evaluation and interpretations of surface elevation change.