Global warming scenario sobering

Geologist calls it N.C.'s biggest issue

If the Earth warms another two or three degrees, the sea level along North Carolina's coast is projected to rise by as much as two feet, accelerating erosion, destroying recreational beaches and possibly inundating parts of the Outer Banks.

"I think this issue is probably the most pressing issue to North Carolina as well as the other coastal states," Jeffress Williams, a coastal marine geologist with the U.S. Geologic Survey, said Friday to a state panel studying the effects of global warming.

The panel is working on recommendations to be presented to the General Assembly, including some that might be ready for the coming session.

Sea level rose about eight inches on North Carolina's coast during the 20th century, Williams said. As temperatures warm two to three degrees and glaciers melt, the ocean is projected to rise more than twice that much -- from 18 inches to two feet -- by 2100, based on projections by an international panel of climate change experts established by the United Nations. The average temperature increased about one degree between 1900 and 2000.

"We in North Carolina need to pay a lot more attention to the potential impacts of sea level rise and do a lot more planning than we are doing," said Rep. Joe Hackney, co-chairman of the state Commission on Global Climate Change and the likely speaker of the House.

For example, Hackney said, information such as rising sea level projections needs to be taken into account when considering where to build roads in coastal areas. A number of scientists have discussed sea level rise, but state lawmakers have yet to incorporate it into decisions about roads, coastal development and other major issues.

Williams said there is scientific consensus that climate change is occurring, though scientists disagree about how much is natural variability and how much humans contribute to the change. Gases such as carbon dioxide and methane -- which occur naturally but are more abundant as a result of industrial activities -- get caught in the atmosphere, creating a greenhouse effect that is warming the planet.

"We ought to be discussing how we adapt to the changes coming along," Williams said.

Williams said that sea level had varied greatly in the distant past. About 120,000 years ago, the ocean was 15 feet higher than it is today. And as recently as 20,000 years ago, when the world was much colder, the ocean was 400 feet lower, such that land creatures could have walked along the edge of the continental shelf.

The ocean began rising as glaciers melted.

If ice in Greenland and Antarctica melts more quickly than projected -- and there are some troubling recent reports of that, Williams said -- that could accelerate sea level rise and the pace of erosion.

Erosion rates vary along North Carolina's coast and even on the same beach because of wave patterns. About a fifth of the coast has severe erosion of more than five feet a year while about two-thirds of the coast is eroding at two feet or less a year, a 2003 state study showed.

How much erosion occurs is a major issue for development. The state's oceanfront setback policy hasn't changed since the 1970s. It places houses a minimum of 60 feet from the ocean, which assumes that the house will be safe for 30 years based on an average erosion rate of two feet per year.

Courtney Hackney, a UNC-Wilmington research scientist, said many houses built during the building boom of the 1980s now stand at the edge of the ocean and are vulnerable to destruction in a big storm.

"This idea that the ocean is coming up does not seem to penetrate into government decisions, at the local level in particular," Hackney said. "There are an awful lot of houses that will be sliding into the ocean, or a lot of money will be spent on beach renourishment."

Hackney said the state needs to develop policies that ban rebuilding of roads and houses in vulnerable areas after major storms. He noted that the state had rushed to plug an inlet and rebuild a section of coastal N.C. 12 on the Outer Banks sliced through by Hurricane Isabel in 2003.

"We should have policies in place so we aren't driven by emotion after big storms to repeat the dumb things we've done before," Hackney said. "There is an awful lot of pressure to relax that setback policy."