All the melting going on the Arctic has some researchers wondering what the world's coastlines would look like if, say, all of Greenland's ice were to melt, or all of Antarctica's. No expert expects either of these scenarios to happen anytime soon, certainly not in the next century. But as a kind of visual thought experiment, the late Bill Haxby of the Lamont-Doherty Earth Observatory at Columbia University created the striking graphics we present below. In these images, see how the coastlines of four regions—the mid-Atlantic U.S. states, Florida, northern Europe, and Southeast Asia—would change if the planet's seas rose 17 feet and 170 feet, respectively.
Why did Haxby choose these two figures? Well, according to Dr. James White (see Ask the Expert), estimates on how much sea levels would rise given certain major ice sheets melting vary depending on the assumption made about rebound of land once the ice disappears, and on the fact that some ice is below sea level. But given these variables, White says, current widely accepted estimates include sea-level rises of about 23 feet if all of Greenland's ice vanished (or about 20 feet if West Antarctica's ice sheet disintegrated), and about 180 feet if the great ice dome of East Antarctica melted away.
So Haxby was being conservative, but as you'll see, the results are unsettling enough. For good measure, Haxby also threw in sea levels 400 feet lower than they are today, showing how coastlines would have looked 20,000 years ago at the height of the Ice Age.—Peter Tyson
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