Size of the West Antarctic ice sheet at the last glacial maximum: new constraints from the Darwin-Hatherton glacial system in the Transantarctic Mountains

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dc.contributor.authorStorey, BCen_AU
dc.contributor.authorHood, Den_AU
dc.contributor.authorFink, Den_AU
dc.contributor.authorShulmeister, Jen_AU
dc.contributor.authorRiger-Kusk, Men_AU
dc.date.accessioned2010-10-25T05:57:19Zen_AU
dc.date.available2010-10-25T05:57:19Zen_AU
dc.date.issued2009-07-01en_AU
dc.date.statistics2009-07-01en_AU
dc.description.abstractAn understanding of how the Antarctic ice sheet has reacted to natural global warming since the last glacial maximum (LGM) 18 to 22 thousand years ago (kya) is essential to accurately predict the response of the ice sheets to current and future climate change. Although global sea level rose by approximately 120 metres since the LGM, the contribution from and rate of change of the Antarctic ice sheets is by no means certain. Mackintosh et al (2007) have suggested that the East Antarctic Ice Sheet (EAIS) made an insignificant contribution to global sea-level rise between 13 and 7 kya raising interesting questions about the initial extent and response of the West Antarctic Ice Sheet (WAIS) during that time frame. Terrestrial evidence of these changes is restricted to a few ice-free areas where glacial landforms, such as moraines, show the extent of former ice advances. One such area is the Darwin-Hatherton glacial system where spectacular moraines preserve the advance and retreat of the glacial system during previous glacial cycles. Previous researchers have suggested that the WAIS was more than 1000 metres thicker than it is today at this location at the LGM. As part of the Latitudinal Gradient Project, we mapped the moraines of the Lake Wellman area bordering the Hatherton Glacier and collected samples for cosmogenic nuclide dating, a technique that is widely used to calculate the exposure history of the glacial landscape and the amount of time that the glacial debris has been exposed to cosmic rays and not covered by ice or other glacial debris. While the technique is very successful in mid latitudes, it is more challenging in Polar Regions. Our mapping has shown that ice in the past was at least 800 metres thicker than current ice levels in this area. Our cosmogenic data suggest that this was at least 2 million years ago but for the most part our data record, as expected, a complex history of exposure and re exposure of the ice free regions in this area in accordance with advance and retreat of the ice sheets. However, a cluster of ages of 35 to 40 thousand years record a single exposure event and indicate that the ice in this area was not as thick as previous estimates for the extent of ice at the LGM. These ages are recorded from moraine boulders that are located below a prominent moraine feature mapped as representing the LGM. These results raise further questions about the size of the Antarctic ice sheets at the LGM, their contribution to global sea level change and how the Antarctic ice sheets respond to global warming.en_AU
dc.identifier.citationStorey, B., Hood, D., Fink, D., Shulmeister, J., & Riger-Kusk, M. (2009). Size of the West Antarctic ice sheet at the last glacial maximum: new constraints from the Darwin-Hatherton glacial system in the Transantarctic Mountains. Presentation to the Annual Antarctic Conference 2009 - "Sustaining the Gains of the International Polar Year", 1st – 3rd July 2009. In Proceedings of the Annual Antarctic Conference 2009, (p. 14). Auckland, New Zealand: University of Auckland.en_AU
dc.identifier.conferenceenddate3 July 2009en_AU
dc.identifier.conferencenameAnnual Antarctic Conference 2009 - 'Sustaining the Gains of the International Polar Year'en_AU
dc.identifier.conferenceplaceAuckland, New Zealanden_AU
dc.identifier.conferencestartdate1 July 2009en_AU
dc.identifier.govdoc2926en_AU
dc.identifier.issn1176-5798en_AU
dc.identifier.pagination14en_AU
dc.identifier.placeofpublicationAuckland, New Zealanden_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/2747en_AU
dc.language.isoenen_AU
dc.publisherUniversity of Aucklanden_AU
dc.subjectAntarcticaen_AU
dc.subjectGreenhouse effecten_AU
dc.subjectIceen_AU
dc.subjectClimatic changeen_AU
dc.subjectSea levelen_AU
dc.subjectGlaciersen_AU
dc.titleSize of the West Antarctic ice sheet at the last glacial maximum: new constraints from the Darwin-Hatherton glacial system in the Transantarctic Mountainsen_AU
dc.typeConference Presentationen_AU
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