N.C. coast called vulnerable

Scientist says storms and a rising ocean could change the look of the Outer Banks

North Carolina's low-lying coastline -- much of it just above the ocean -- is vulnerable to rising oceans caused by climate change, scientists speaking at N.C. State University and the Museum of Natural Sciences said Wednesday.

The Outer Banks barrier islands that fringe the coast are especially fragile and could break into small isolated islands if a hurricane packing the power of Katrina slammed into them, said Stephen Culver, a geologist at East Carolina University, during a pair of discussions about climate change.

Culver said the Outer Banks looked very different as recently as 500 to 600 years ago and could change its profile again in the not-too-distant future.

"It's likely future hurricanes will be more intense in North Carolina," Culver said. "We've got to have a realistic disaster recovery plan in place."

Higher temperatures are expected to further raise sea levels by expanding ocean water, melting mountain glaciers and causing portions of Greenland and the Antarctic ice sheets to melt, federal scientists say. An international panel has projected that sea levels could rise from about 7 inches to 2 feet in the next century.

Those predictions don't include recently observed increased rates of melting glaciers and ice sheets because scientists aren't confident in their ability to project them.

The average temperature increased about 1 degree between 1900 and 2000, and the rate of warming has accelerated over the past 30 years. Scientists say that much of the temperature change in the past 50 years has likely been caused by human activities such as burning coal and oil. That has raised the levels of heat-trapping carbon dioxide gases in the atmosphere, creating the greenhouse effect.

Waleed Abdalati, head of NASA's science branch that studies ice-covered regions, cited the retreat of ice sheets in portions of Greenland and Antarctica and the shrinking of glaciers around the world as warning signs. He said the ice sheets were responding dramatically to temperature change.

"We're perturbing the system in a big way, and I think the ice is showing that," Abdalati said Wednesday at NCSU's Millennium seminar series.

He said an ice-free Arctic Sea during summertime is a real possibility by the end of the century, which could affect climate.

Ice in the polar regions affects the ocean's circulation patterns, which in turn influence climate. Because of the warm Gulf Stream, for instance, Great Britain enjoys warmer temperatures than other countries at similar latitudes.

Abdalati said that the levels of carbon dioxide in the Earth's atmosphere are higher than ever before.

"Climatologically, we're in uncharted territory," he said.

Abdalati said scientists can't say for sure that the West Antarctic ice sheet is in a state of decay, but he said the melting that scientists are observing suggests that.

"There is an instability that we are watching carefully," he said.

Fred Semazzi, a professor of Earth and Atmospheric Sciences at NCSU, said many of the current computer models that predict climate change are mainly useful on a large global scale. He said future models would be more predictive of climate changes at the regional and state scale.