NASA is already planning for the day when parts of the Kennedy Space Center, on Florida’s Cape Canaveral, will be underwater.
According to the Intergovernmental Panel on Climate Change, sea levels could rise by more than three feet by the end of this century. The United States Army Corps of Engineers projects that they could rise by as much as five feet; the National Oceanic and Atmospheric Administration predicts up to six and a half feet. All these projections are probably low.
Many geologists, are looking at the possibility of a ten-to-thirty-foot range by the end of the century.
The amount of water on the planet is fixed (and has been for billions of years). Its distribution, however, is subject to all sorts of rearrangements. In the coldest part of the last ice age, about twenty thousand years ago, so much water was tied up in ice sheets that sea levels were almost four hundred feet lower than they are today. At that point, Miami Beach, instead of being an island, was fifteen miles from the Atlantic Coast. Sarasota was a hundred miles inland from the Gulf of Mexico, and the outline of the Sunshine State looked less like a skinny finger than like a plump heel.
As the ice age ended and the planet warmed, the world’s coastlines assumed their present configuration. There’s a good deal of evidence—much of it now submerged—that this process did not take place slowly and steadily but, rather, in fits and starts.
As temperatures climb again, so, too, will sea levels. One reason for this is that water, as it heats up, expands. The process of thermal expansion follows well-known physical laws, and its impact is relatively easy to calculate. It is more difficult to predict how the earth’s remaining ice sheets will behave, and this difficulty accounts for the wide range in projections.
