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Stability of Larsen C Ice Shelf in a Warming Climate


Significant glaciological and ecological changes are occurring along the Antarctic Peninsula in response to climate warming that is proceeding at 6 times the global average rate (King et al., 1994; Vaughn et al., 2003). Floating ice shelves, the extension of outlet glaciers, are responding rapidly and have lost ~28,000 km2 in the last 50 years, including the catastrophic collapse of Larsen A in 1995, Larsen B in 2002 and the Wilkins ice shelf in 2008-09 (Cook and Vaughn, 2009). Following ice shelf collapse, the outlet glaciers that nourished the ice shelves have accelerated and thinned in response to the removal of the backstress that the ice shelf provided. In the case of Larsen B, an additional -27 km3 yr-1 of ice was discharged due to the removal of this backstress (Rignot et al., 2004).

The significance of ice shelf collapse and subsequent acceleration of outlet glaciers is amplified by the fact that 40% of the Antarctic continent is ringed in ice shelves and that 80% of ice flux from the continent passes through these gates (Drewy, 1982; Jacobs et al., 1992). The climatic regime of the Antarctic Peninsula and the latitudinal changes in ice shelf stability provide a unique opportunity to study the full spectrum of ice shelf stability—from recently collapsed to fully stable—in order to gain a broader understanding of the climatic conditions and physical processes that result in ice shelf stability and instability. This understanding is essential to future estimates of ice sheet contributions to global sea level rise.

This project focuses on Larsen C, the largest remaining ice shelf on the Antarctic Peninsula. Larsen C has a surface area of ~55,000 km2 and is composed of 12 major flow units fed by outlet glaciers (Glasser et al., 2009). Average ice thickness is ~300 m but ranges from ~500 m near the grounding line to ~250 m near the ice edge (Griggs and Bamber, 2009).

Source: Cooperative Institute for Research in Environmental Sciences CIRES