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Will sea levels rise 20 feet as Gore predicts?

By Dennis T. Avery
web posted July 17, 2006

Al Gore's movie An Inconvenient Truth. says human-emitted CO2 will boost the earth's temperatures enough to melt the Arctic ice cap -- and suddenly raise sea levels by 20 feet.


First of all, let's understand just how cold the Antarctic is. Winter temperatures on its high, cold interior plateau range from 40 to 95 degrees F below zero! In the summer (December) it "warms," with temperatures dipping only to 49 degrees F below zero -- and sometimes rising within 25 degrees F of the melting point (32 degrees F). But even then, the ice reflects virtually all of the sun's rays back out into space.

However, the world's warming in the past 150 years has produced a change in Antarctica. The huge East Antarctic ice sheet, which contains nearly 90 percent of the world's ice, has been thickening. European satellites measured the ice sheet's thickness 347 million times between 1992 and 2003, and found it is gaining about 45 billion tons of water per year because the planet has warmed enough for snow to fall at the coldest place on earth.

The study, "Snowfall-driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-level Rise." was led by Curt Davis of the University of Missouri, and reported in Science on June 24, 2005.

Thickening ice in the Antarctic, in fact, is just about offsetting the meltwater being released from the edges of the Greenland ice sheet -- which has also been thickening in its center. This leaves us with a global warming sea level gain of about 1.8 millimeters per year -- or 4 inches per century. The rise has remained constant during the 20th century despite the moderate 0.6 degree C warming of the planet.

In the movie, a whole Antarctic ice sheet shatters on Gore's computer screen. In the real world, that isn't happening. It is only the Antarctic Peninsula -- 2 percent of the continent's land area that sticks up toward the far-off equator -- that is warming. It recently earned headlines by calving an ice floe as big as Rhode Island, not an unusual event.

But the East Antarctic ice sheet is more than 2,000 times bigger than Rhode Island, and the ice is two miles thick! John Stone of the University of Washington, reporting in Science on January 3, 2003 says the West Antarctic ice sheet has been retreating so slowly for the past 10,000 years that it still has not fully accommodated the end of the last Ice Age, and apparently still has about 7,000 years of ice to melt -- and the East Antarctic ice sheet is melting even more slowly than that.

So. Al Gore says Antarctic melting will suddenly raise the sea levels by 20 feet, and the experts say 4 inches per century. Seth Borenstein, an AP science writer, did a column on June 27 headlined, "Scientists OK Gore's Movie for Accuracy." The dean of environmental studies at Duke is quoted as saying "He got all the important material and got it right."

Were they talking about the same movie I saw? Gore overstated the impact of global warming on the Antarctic glaciers by about 50-fold. Or did he mean that 7000 years was "sudden"? How can so-called scientists applaud his accuracy either way?

Dennis T. Avery was a senior policy analyst for the U.S. State Department, where he won the National Intelligence Medal of Achievement. He is the co-author, with atmospheric physicist Fred Singer, of the forthcoming book Unstoppable Global Warming -- Every 1500 Years, due in October from Rowman & Littlefield.





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