C11D-08
Direct evidence of warm water access to the Totten Glacier sub-ice shelf cavity
Monday, 14 December 2015: 09:45
3007 (Moscone West)
Stephen R Rintoul1,2, Alejandro Hector Orsi3, Alessandro Silvano4, Esmee van Wijk2, Beatriz Pena-Molino1 and Mark Andrew Rosenberg5, (1)Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), Hobart, Australia, (2)CSIRO Oceans & Atmosphere Flagship, Hobart, Australia, (3)Texas A & M University, College Station, TX, United States, (4)University of Tasmania, Quantitative Marine Science Program, Hobart, Australia, (5)Antarctic Cooperative Research Centre, CSIRO, Hobart, Australia
Abstract:
The Totten Glacier holds enough ice to raise global sea level by 3.5 m, is thinning according to (some) satellite data, and is grounded well below sea level on a retrograde bed and hence is potentially unstable. Basal melt driven by ocean heat flux has been linked to ice shelf thinning elsewhere in Antarctica, but no oceanographic measurements had been made near the Totten. In January 2015 the RSV Aurora Australis was the first ship to reach the Totten calving front. Observations from ship-board CTD, moorings and profiling floats provide direct confirmation that warm water reaches the ice shelf cavity. Warm water is present near the sea floor at every station deeper than 300 m depth, with maximum temperatures at mid-shelf >0.5°C. Mooring data confirm that the warm water is present year-round. A deep (>1100 m) channel at the calving front allows warm water (-0.4°C, >2°C above the local freezing point) to access the ice shelf cavity. The contrast between the oceanographic conditions near the Totten and near the Mertz Glacier is stark, although they are separated by only 30 degrees of longitude. East Antarctic ice shelves have often been assumed to behave in a similar manner and to be invulnerable to ocean change; these measurements suggest these assumptions need to be reconsidered.
