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Laboratory experiments investigating the influence of fjord circulation on outlet glacier melting

Arctic Research Initiative
2009 Funded Project

Abstract

Beginning in 1996, Greenland’s outlet glaciers rapidly retreated and accelerated, increasing their discharge to the ocean and contributing more noticeably than in the past to sea-level rise. A similar trend has also been observed around the Antarctic ice sheets. The magnitude of the acceleration of these glaciers was unexpected to many glaciologists, whose numerical models of large ice sheets have variations in ice mass on millennial–timescales. Clearly, this highlights our lack of thorough understanding of the dynamics regulating the motion of glaciers. In particular, the boundary conditions regulating the interaction of glaciers with surrounding sediments, rock and water are poorly understood. As highlighted by the Intergovernmental Panel on Climate Change (IPCC) in 2007, today the largest uncertainty in predicting sea-level rise comes from the lack of a correct representation in climate models of the rapid changes observed in outlet glaciers. 

Recently, a new mechanism has been identified as a possible candidate to explain the recent acceleration in glacial discharge into the ocean. Greenland’s largest outlet glaciers terminate at tidewater in deep fjords and additional heat delivered by subsurface waters may be melting the submarine bases of these glaciers. The recent warming of the ocean around southeast and western Greenland and the recently observed warm waters in Greenland’s fjords are the supporting evidence for this mechanism. This scenario highlights the possibility for the ocean to play a significant role in the recent increase of glacial discharge. Hence the need to better understand the interaction between the ocean and the ice. Several questions then arise: What is the influence of the fjord circulation on the ice-ocean interface melting rates? Can one circulation be more efficient than another in delivering the heat from the open ocean to the base of the outlet glaciers? 

In order to answer these questions I propose to use a set of idealized laboratory experiments to investigate the efficiency of various fjord circulations in transporting heat to the outlet glaciers.  Furthermore, I will investigate the influence of upstream surface meltwater coming out at the base of the glacier on the melting of the ice-ocean interface and the fjord circulation. The product of this study will be an improved understanding of the influence of: a) the fjord circulation on glacier’s melting rates; and b) the upstream basal meltwater flow and distribution in the fjord. 

If funded, this study will give me the unique opportunity to expand my research to a new and exciting field that is growing fast and addressing questions of great societal impact. The amount of glacial discharge has a direct impact on sea-level rise and the change in the amount of fresh water in the open ocean can cause drastic changes to the ocean circulation with consequent climate changes. This study will foster interdisciplinary collaboration since it is complementary to the recent work that Drs. Straneo (PO) and Das (G&G) are conducting in Greenland glaciers. 

This collaboration will initiate an interdisciplinary group on “ocean-ice sheet interaction” expertise here at WHOI that will surely benefit the scientific community and WHOI in the foreseeable future. Finally, this study will allow me to become experienced enough to submit a larger study to NSF.

Last updated: September 14, 2010