Last major retreat of Antarctic ice sheets forced by sea level rise and ocean warming.

• Main Authors: Mackintosh, AN, Domack, E, Golledge, NR, Dunbar, R, Leventer, A, White, D, Fink, D, Gore, DB, Lavoie, C
• Format: Conference Object
• Language: English
• Published: 2009
• Subjects: Antarctica; Ice; Quaternary period; Sea level; Greenhouse effect; Climatic change; Antarctic; East Antarctic Ice Sheet; East Antarctica; Mac.Robertson Land; Weddell; Weddell Sea; Antarc*; Ice Sheet
• Online Access: http://apo.ansto.gov.au/dspace/handle/10238/2745

The retreat of Antarctic ice sheets during the transition from the last glacial period to the Holocene provides the most recent example of ice sheet response to major climate forcing and thus allows rates of ice sheet decay and coupling to sea level rise to be quantified. We observe through a combination of land- and marine-based geochronology and ice sheet modelling, a highly-resolved temporal record of deglaciation of the East Antarctic Ice Sheet across the Mac.Robertson Land shelf. Our reconstruction demonstrates that deglaciation of deep-shelf troughs and lowering of the ice sheet surface occurred in two phases, from 14 - 12 and 12 - 7 ka before present (BP). Our consideration of possible mechanisms for the observed retreat of the marine ice margin of Mac.Robertson Land favours rapid rates of eustatic sea level rise associated with Meltwater Pulse 1a (MWP-1a) at ~14 ka BP and warming of the marginal oceans and atmosphere to nearmodern levels ~2 ka later. In support of this interpretation is the comparison of our land-marine sequence to other well-constrained marine deglacial events from both West and East Antarctica, including the Ross and Weddell Sea embayments. Our results show that periods of rapid sea level rise can initiate instability in Antarctica’s ice masses, including the margins of East Antarctica, and indicate that a combination of sea level rise and oceanic warming is a powerful driver of ice retreat.