Rise in central west Greenland surface melt unprecedented over the last three centuries
Abstract
Melting of Greenland Ice Sheet (GrIS) surface has intensified and expanded over the last several decades. Prior to the satellite ( 1978-) and climate reanalysis ( 1958-) eras, few direct records of ice sheet melt variability exist. This observational paucity limits the understanding of processes governing melt and the degree of anomaly of observed melt trends. To constrain the longer-term evolution of surface melt across central and west Greenland, we quantify layers of refrozen melt in multiple well-dated (subannual resolution) firn and ice cores collected in 2014 and 2015 as well as from several legacy cores. These ice core melt records are then assessed with respect to observed and modeled melt dynamics from microwave remote sensing and the regional climate model RACMO2.3. Significant agreement among these varied datasets confirms the fidelity of select ice core archives as quantitative records of past variability in the magnitude of surface melt. Moreover, we find a significant agreement between the melt records derived from our 100-m GC-2015 core (2436 m.a.s.l.) and the 150-m D5 core (2473 m.a.s.l.) collected in 2003 and located 50 km to the southeast, thus demonstrating the feasibility of deriving regional melt history from a single site, despite the potential for high local variability in melt percolation and refreeze. The linked GC-D5 ice core record reveals that the melt intensification of the last several decades in central west Greenland is unprecedented over the last 340 years, with 2012 being the most extreme melt year on record. Our 140-m ice core from Nuussuaq Peninsula (1980 m.a.s.l.), west Greenland, reveals a similar melt intensification over this period and offers an important new record linking the GrIS to existing melt reconstructions from the Canadian Arctic. To discern the potential broader spatial representation of each ice core site, we examine spatial correlations between these sites and our satellite and modeled melt datasets. We find that central Greenland melt records correlate broadly with satellite and modeled melt fields across the GrIS. Notably, a significant correlation exists with modeled meltwater runoff across several GrIS drainage basins, and thus our ice core melt records may also offer unique, observationally-derived insights into past variability in ice sheet mass losses.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.C54A..02T
- Keywords:
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- 0762 Mass balance 0764 Energy balance;
- CRYOSPHEREDE: 0794 Instruments and techniques;
- CRYOSPHEREDE: 0798 Modeling;
- CRYOSPHERE