Futur of Antartic

Future changes in the size of the Antarctic ice sheet

There has been much speculation that climate change could lead to a collapse of the polar ice sheets. Future ice sheet predictions must be based on reliable predictions of climate and an understanding of the controls on the ice sheet. The Intergovernmental Panel on Climate Change (IPCC) predicted that global mean temperatures will rise by between 1°C and 3.5°C by the year 2100; their "best" estimate is 2.0°C. However, local changes may be quite different to the average. In polar regions precipitation will increase, and Antarctica will probably experience less warming than the Arctic. A few meteorological records from Antarctica have shown more warming than predicted, whilst others have shown no change at all.

While ice shelves are not a direct influence on sea level because they are already floating, it has been argued that the Ross and Ronne-Filchner ice shelves help to stabilise the ice sheet in West Antarctica and so indirectly help to control sea level. Scientists are still unsure if the ice sheet would collapse if these ice shelves retreated. A total loss of the West Antarctic ice sheet would raise sea level by an average of 6m. Fortunately, these ice shelves are a long way south of the Antarctic Peninsula, and the West Antarctic climate is much colder so the local ice sheet is unlikely to be threatened by melting in the next 200 years. The authoritative Intergovernmental Panel on Climate Change (IPCC) says the likelihood of a major sea level rise by the year 2100 due to a collapse of the West Antarctic ice sheet is considered low. For planning purposes, however, the low likelihood must be balanced against the severity of its impact.

Ironically there is an opposing effect that scientists are more confident in predicting. If the southern hemisphere climate warms, warmer air will transport more moisture to Antarctica. This will give more precipitation, and the ice sheet will respond by becoming thicker. So over the next century changes in Antarctica may oppose sea level rise, although they are unlikely to be sufficient to completely counteract the thermal expansion of the oceans and the melting of glaciers outside the Antarctic region