Author:
Budd W. F.,Coutts B.,Warner Roland C.
Abstract
The future behaviour of the Antarctic ice sheet depends to some extent on its
current state of balance and its past history. The past history is primarily
influenced by global climate changes, with some small amount of local feedback,
and by sea-level changes generated primarily by the Northern Hemisphere ice-sheet
changes, again with a small amount of feedback from the Antarctic ice sheet. An
ice-sheet model which includes ice shelves has been used to model the Antarctic
region and the whole Northern Hemisphere high-latitude region through the last
ice-age cycle. For the climate forcing, the results from the global energy-balance
model of Budd and Rayner (1990) are used. These are based on the Earth's orbital
radiation changes with ice-sheet albedo feedback. Additional sensitivity studies
are carried out for the amplitudes of the derived temperature changes and for
changes in precipitation over the ice-sheets. For the Antarctic snow-accumulation
changes, the results from the Voslok ice core are used with proportional changes
over the rest of the ice sheet. For the sea-level variations, the results
generated by the Northern Hemisphere ice-sheet changes provide the primary
forcing, but account is also taken of the feedback effects from bed response under
changing ice and ocean loading and from the Antarctic changes.
The results of the modelling provide a wide range of features for comparison
with observations, such as the margins of maximum ice extent. For the Northern
Hemisphere the results indicate that the peak mean temperature shift required for
the ice-edge region is about -12°C, whereas outside the ice-sheet region this
change is smaller but over the ice sheets it is larger. For the Antarctic region
during the ice age the interior region decreases in thickness, due to lower
accumulation, while the grounding-edge region expands and thickens due to the
sea-level lowering. As a result, the derived present state of balance shows a
positive region over most of inland East Antarctica, whereas coastal regions tend
to be nearer to balance, with some slightly negative regions around some of the
large ice shelves and coastal ice streams which are still adjusting slowly to the
post-ice-age changes of sea level and accumulation rates.
Publisher
International Glaciological Society
Cited by
22 articles.
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