ABSTRACT
One million years of paleoclimatic data tell a consistent and convincing story – a warmer Earth contains less ice. Given that the IPCC Fourth Assessment Report predicts a temperature increase of 1.1–6.4°C over the next century, we can expect the amount of ice on the planet to decrease. Just how fast this decrease will occur, however, is still not well established as scientists are working to understand the mechanisms that control how fast the ice sheets will melt. What we do know is that records of sea level in ancient coral show that, as the ice sheets retreated at the end of the last glaciation, sea level rose at a rate up to 30 times faster than the present rate of rise, suggesting that once ice sheets begin to melt, extended episodes of ice loss can be relatively rapid. Understanding what this would mean for the Antarctic Ice Sheet, particularly the West Antarctic Ice Sheet that is grounded below sea level, is the focus of this chapter.
