Question

At about what time will the polar caps melt and when they do will it flood the earth?

Melting of polar ice is one of the worst potential consequences of global warming. First, global warming is affecting the high latitudes most, with rises of several degrees happening there. Second, as the ice melts it exposes darker land or ocean underneath, and that increases the absorption of sunlight. This is a positive feedback effect that can accelerate global warming. There are some predictions that within a decade or two the Artic Ocean will be ice-free in summer. Third, the melting of polar ice caps on land will raise the level of the ocean. Melting of sea ice in the Arctic Ocean will not raise sea levels, so the places we worry about are Greenland and the Antarctic continent. If most of the Greenland and Antarctic ice melted, the rise in sea level would flood out most coastal cities, from Los Angeles and Miami and New York to Shanghai, Mumbai, and London, displacing at least a billion people. But no amount of melting would flood the Earth, just the coastal regions. Also, scientists cannot predict how fast the ice will melt, since we are only beginning to make the measurements of ice loss in Greenland and the Antarctic.

David Morrison
NAI Senior Scientist
August 25, 2009