Abstract
Widespread glacier acceleration has been observed in Greenland in the past few years. Oceanographic observations taken in summer 2008 show that ocean waters melted a substantial fraction of ice along the calving fronts of three West Greenland glaciers, indicating that submarine melting has a profound influence on grounding-line stability. Widespread glacier acceleration has been observed in Greenland in the past few years1,2,3,4 associated with the thinning of the lower reaches of the glaciers as they terminate in the ocean5,6,7. These glaciers thin both at the surface, from warm air temperatures, and along their submerged faces in contact with warm ocean waters8. Little is known about the rates of submarine melting9,10,11 and how they may affect glacier dynamics. Here we present measurements of ocean currents, temperature and salinity near the calving fronts of the Eqip Sermia, Kangilerngata Sermia, Sermeq Kujatdleq and Sermeq Avangnardleq glaciers in central West Greenland, as well as ice-front bathymetry and geographical positions. We calculate water-mass and heat budgets that reveal summer submarine melt rates ranging from 0.7±0.2 to 3.9±0.8 m d−1. These rates of submarine melting are two orders of magnitude larger than surface melt rates, but comparable to rates of iceberg discharge. We conclude that ocean waters melt a considerable, but highly variable, fraction of the calving fronts of glaciers before they disintegrate into icebergs, and suggest that submarine melting must have a profound influence on grounding-line stability and ice-flow dynamics.
Highlights
Widespread glacier acceleration has been observed in Greenland in the past few years[1,2,3,4] associated with the thinning of the lower reaches of the glaciers as they terminate in the ocean[5,6,7]
We conclude that ocean waters melt a considerable, but highly variable, fraction of the calving fronts of glaciers before they disintegrate into icebergs, and suggest that submarine melting must have a profound influence on grounding-line stability and ice-flow dynamics
50–60% of that loss was caused by an acceleration of the outlet glaciers; the remainder resulting from an increase in surface melt
Summary
Widespread glacier acceleration has been observed in Greenland in the past few years[1,2,3,4] associated with the thinning of the lower reaches of the glaciers as they terminate in the ocean[5,6,7]. We present measurements of ocean currents, temperature and salinity near the calving fronts of the Eqip Sermia, Kangilerngata Sermia, Sermeq Kujatdleq and Sermeq Avangnardleq glaciers in central West Greenland, as well as ice-front bathymetry and geographical positions. To model the forced convective flow into the fjord and derive its mass and heat budgets, we modified the method of Motyka and colleagues[9] In this two-layer approach, subglacial water discharge drives ocean convection, drawing deep, warm saline waters towards the near-vertical terminal ice face, where the two components turbulently mix and rise along the face to reach the surface and flow away from the terminus in an overflow plume (Fig. 2). In TOR, similar jets are found in the top 60 m to the north and
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