The Heat Is Online

Rate of Sea Level Rise Doubles


The Seattle Times, July 10, 2005


WASHINGTON -- Melting ice and warming waters have raised average sea levels worldwide by more than an inch since 1995, new data from space satellites and robotic submarines have revealed.


That's twice as fast as the rate the oceans rose during the previous 50 years, ocean experts said yesterday. If the current rate continues or accelerates, as they say is likely, the world's seas will rise at least a foot by the end of this century, causing widespread flooding and erosion of islands and low-lying coastal areas.


"Even a small change will matter to a whole lot of coastal people," said Richard Alley, a geoscientist at Penn State University in State College. "If 15 percent of Greenland ice sheet were to melt, much of South Florida would be underwater."


More than half the sea rise was caused by a recent speedup in the melting of glaciers and ice sheets, especially in Greenland and Antarctica, according to Laury Miller, chief of the Laboratory for Satellite Altimetry at the National Oceanic and Atmospheric Administration.


Glaciers in Alaska and South America "are shrinking faster now than 10 years ago, and two to three times faster than they did over the last century," Rignot said. Mountain glaciers in Europe, Asia and Africa also are contracting rapidly.


Even more dramatic melting is going on in the much larger glaciers and ice sheets of Antarctica. A chunk of ice as large as Rhode Island collapsed off the coast of the frozen continent three years ago.


Particularly worrisome is an area called Pine Island Bay. "There's enough ice in that sector alone to raise the sea level by 1 full meter," or 39 inches, Rignot said.


The remaining increase in sea level is mostly the result of higher water temperatures, because water naturally expands as it warms.


A sea-level rise of one-eighth inch per year -- about a 1.2-inch rise every 10 years -- may not sound like much, Miller said. But by the end of the century, that a foot, bringing not only higher seas but also more widespread erosion.


"The problem at the coastline is more than just the vertical rise of the water," Miller said. "The erosion effect over a century could be as much as 50 to 100 feet of coastline eroded, just with the numbers that we're seeing today."


The new evidence of rising seas comes from NASA satellites launched in the last two or three years, and deep-sea subs.


Copyright 2005 The Seattle Times Company