Abstract
Abstract. The southern Bellingshausen Sea (SBS) is a rapidly-changing part of West Antarctica, where oceanic and atmospheric warming has led to the recent basal melting and break-up of the Wilkins ice shelf, the dynamic thinning of fringing glaciers, and sea-ice reduction. Accurate sea-floor morphology is vital for understanding the continued effects of each process upon changes within Antarctica's ice sheets. Here we present a new bathymetric grid for the SBS compiled from shipborne multibeam echo-sounder, spot-sounding and sub-ice measurements. The 1-km grid is the most detailed compilation for the SBS to-date, revealing large cross-shelf troughs, shallow banks, and deep inner-shelf basins that continue inland of coastal ice shelves. The troughs now serve as pathways which allow warm deep water to access the ice sheet in the SBS. Our dataset highlights areas still lacking bathymetric constraint, as well as regions for further investigation, including the likely routes of palaeo-ice streams. The new compilation is a major improvement upon previous grids and will be a key dataset for incorporating into simulations of ocean circulation, ice-sheet change and history. It will also serve forecasts of ice stability and future sea-level contributions from ice loss in West Antarctica, required for the next IPCC assessment report in 2013.
Highlights
Contributions to sea level from 21st Century changes in the West Antarctic ice sheet (WAIS) will form a key part of the Fifth Assessment Report of the IPCC due in 2013
In May 2008 the Wilkins ice shelf dramatically disintegrated and recent satellite measurements of icesurface elevation have indicated that glaciers which drain into the southern Bellingshausen Sea (SBS) have undergone dynamic thinning related to warming delivered through the oceans (Rignot and Jacobs, 2002; Pritchard et al, 2009), and as a result of the southerly migration of regional isotherms
Oceanographic data have shown the SBS is a key area where warm Circumpolar Deep-Water (CDW; temperature ≥1.0 ◦C, salinity 34.7 psu) periodically floods onto the shelf (Talbot, 1988; Jenkins and Jacobs, 2008), and coupled thermodynamic models indicate that ice shelves in the SBS have been thinning rapidly as a result of basal melting, possibly for some decades (Holland et al, 2010)
Summary
Contributions to sea level from 21st Century changes in the West Antarctic ice sheet (WAIS) will form a key part of the Fifth Assessment Report of the IPCC due in 2013. In May 2008 the Wilkins ice shelf dramatically disintegrated and recent satellite measurements of icesurface elevation have indicated that glaciers which drain into the SBS have undergone dynamic thinning (thinning as a result of flow acceleration) related to warming delivered through the oceans (Rignot and Jacobs, 2002; Pritchard et al, 2009), and as a result of the southerly migration of regional isotherms (i.e. atmospheric warming; Cook and Vaughan, 2010). A major ice stream, Ferrigno Glacier, which drains into Eltanin Bay, thinned by more than 0.5 m yr−1 between 2003–2007 (Pritchard et al, 2009) and currently exhibits thinning rates of ca. It is of little surprise that a major focus of UK and US environmental research is the fast-changing SBS area
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