PP12B-04:
Antarctic contribution to meltwater pulse 1A from reduced Southern Ocean overturning
Monday, 15 December 2014: 11:05 AM
Nicholas R Golledge1, Laurie Menviel2, Lionel Carter1, Christopher Joseph Fogwill2, Matthew H England3, Giuseppe Cortese4 and Richard H Levy4, (1)Victoria University of Wellington, Antarctic Research Centre, Wellington, New Zealand, (2)University of New South Wales, Climate Change Research Centre, Sydney, NSW, Australia, (3)University of New South Wales, Sydney, Australia, (4)GNS Science, Lower Hutt, New Zealand
Abstract:
During the last glacial termination, the upwelling strength of the southern polar limb of the Atlantic Meridional Overturning Circulation varied, changing the ventilation and stratification of the high-latitude Southern Ocean. During the same period, at least two phases of abrupt global sea-level rise - `meltwater pulses' - took place. Although the timing and magnitude of these events have become better-constrained, a causal link between ocean stratification, the meltwater pulses, and accelerated ice loss from Antarctica has not been proven. Here we simulate Antarctic ice sheet evolution over the last 25 kyr using a data-constrained ice-sheet model forced by changes in Southern Ocean temperature from an Earth system model. Results reveal several episodes of accelerated ice-sheet recession, the largest being coincident with meltwater pulse 1A. This resulted from reduced Southern Ocean overturning following Heinrich Event 1, when warmer subsurface water thermally eroded grounded marine-based ice and instigated a positive feedback that further accelerated ice-sheet retreat.
