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Characterising ice sheets during the Pliocene: evidence from data and models

Climate models reveal a smaller, but persistent Antarctic ice sheet during Earth’s last major warm period

According to new research by BAS Ice Sheet Modeller Daniel Hill and colleagues, the last time global temperatures were higher than they are today the East Antarctic Ice Sheet was significantly smaller than it is now, but did not disappear completely.

The Pliocene epoch (5.3 to 1.8 million years ago) is the last period of geological time when global temperatures were generally warmer than they are presently. In this paper, new models suggest that climate variations (2.1ºC higher than today) were not sufficient to trigger a major deglaciation of East Antarctica during this period. There was, however, a smaller, persistent ice-sheet, with the main reduction in ice over the Wilkes and Aurora subglacial basins (Wilkes Land).

The models show that even the largest reconstructed extents of the East Antarctic Ice Sheet during the Pliocene are smaller than today, with at least an 8% reduction in ice cover. This suggests that previous theories of a stable, unchanging ice sheet cannot be extended to the entire continent.

Studying the East Antarctic Ice Sheet during the warmer conditions of the past is essential to aid our understanding of the future behaviour of Earth’s ice sheets in a warmer world. The climate of the mid-Pliocene draws parallels with those predicted for the year 2100 by the Intergovernmental Panel on Climate Change (IPCC). This paper reinforces Antarctica’s key role in predicting the global effects of future climate change.

Read this paper in the NERC Open Research Archive.

Authors

Dan Hill (BAS), Alan Haywood (Univ. of Leeds), Richard Hindmarsh (BAS) and Paul Valdes (Univ. of Bristol)

Publication

Deep-time perspectives on climate change: marrying the signal from computer models and biological proxies. Williams, M., Haywood, A.M., Gregory, F.J. & Schmidt, D.N., eds. Micropalaeontological Society Special Publications, The Geological Society, London, 517-538, 2007.