The primary effects of global warming on the Antarctic ice sheet can involve
increases in surface melt for limited areas at lower elevations, increases in net
accumulation, and increased basal melting under floating ice. For moderate global
wanning, resulting in ocean temperature increases of a few °C, the
large- increase in basal melting can become the dominant factor in
the long-term response of the ice sheet. The results from
ice-sheet modelling show that the increased basal melt rates lead to a reduction
of the ice shelves, increased strain rates and flow at the grounding lines, then
thinning and floating of the marine ice sheets, with consequential further basal
melting.
The mass loss from basal melting is counteracted to some extent by the
increased accumulation, but in the long term the area of ice cover decreases,
particularly in West Antarctica, and the mass loss can dominate. The ice-sheet
ice-shelf model of Budd and others (1994) with 20 km resolution has been modified
and used to carry out a number of sensitivity studies of the long-term response of
the ice sheet to prescribed amounts of global warming. The changes in the ice
sheet are computed out to near-equilibrium, but most of the changes take place
with in the first lew thousand years. For a global mean temperature increase of
3°C with an ice-shelf basal melt rate of 5 m a−1 the ice
shelves disappear with in the first few hundred years, and the marine-based parts
of the ice sheet thin and retreat. By 2000 years the West Antarctic region is
reduced to a number of small, isolated ice caps based on the bedrock regions which
are near or above sea level. This allows the warmer surface ocean water to
circulate through the archipelago in summer, causing a large change to the local
climate of the region.
Supplementary material to "Long-term response of oceanic carbon uptake to global warming via physical and biological pumps"
