Remarkably, the appearance does not reflect reality. In year 2000, the IPCC
knew that the GRACE satellite measurements were imminent, and so they had
scientists calculate how much ice change was expected from global warming. The
surprising result was that all the scientists predicted that global warming would
increase the ice of Antarctica, not decrease it. The reason for this is not hard to
see. Even with 1 or 2 degrees warming, most of Antarctica remains very cold.
Loss of ice mass comes not from melting but from calving, the breaking off of ice
as it flows to the sea. With additional warming, the main effect (according to the
calculations) was additional evaporation from the sea; warm weather evaporates
water. When this water vapor drifts over the continent of Antarctica, it results in 10-15
added snow, which compresses to ice – and the glaciers were expected to grow.
So global warming was predicted to increase the Antarctic ice mass, not decrease
it. Had they seen the ice mass increase, scientists might have concluded that their
prediction was verified, and that the increase was additional evidence for global
warming.
The opposite is what was observed. Does this disagree with the global
warming picture? Yes. Does it disprove global warming? No – the temperature
evidence is very strong. It does show that our current understanding of the
warming is not good enough even to predict huge ice changes in Antarctica.
from Physics For Future Presidents by Richard A. Muller