Next sea-level forecast will look only 30 years ahead

by Bruce Siceloff, News and Observer, May 16, 2014.

Hoping to avoid a repeat of the uproar sparked in 2010 when a state science panel warned of a possible 39-inch rise in sea level by the end of this century, the N.C. Coastal Resources Commission decreed Thursday that the next official forecast will look no farther than 30 years into the future.

“We could add credibility to the study if we limit the time frame we’re asking people to consider,” commission chairman Frank Gorham III said.

Many critics of the panel’s earlier forecast had attacked its premise that the recent slow rate of sea-level rise would begin a dramatic acceleration sometime later in this century. They ridiculed a “hockey stick” curve used to portray a rapid rise that would submerge much of the coast by 2100.

But there should be little disagreement next year, commissioners and scientists agreed Thursday, when the advisory panel of geologists and engineers issues a new forecast that is likely to show only a moderate increase for the next 30 years.

The commission will ask for a “rolling 30-year update” of the forecast every five years, Gorham said.

“If it turns out 10 years from now there is a hockey stick starting, we’re going to see that in five or 10 years,” Gorham said.

The science panel’s original report said the sea-level forecast for 2100 was uncertain, and it cited projections ranging from 15 inches to five feet. Asked to settle on one number, the panel concluded that the state should plan for a possible rise of 39 inches.

Developers and political leaders worried that the warning would chill the coastal economy. The state legislature in 2012 told the Coastal Resources Commission to develop a new forecast, and it ordered a moratorium on sea-level policy until 2016. The commission took up this assignment Thursday.

Commission member Bob Emory of New Bern agreed with Gorham that a 30-year focus will give the state a more solid base for making new regulations. But he argued that the scientists also should be allowed to consider a longer time horizon.

“I don’t see why we couldn’t do both,” Emory said. “We can make clear that, based on an 85- or 100-year forecast, we’re not calling for regulation. But we can provide it for the public as an informational and educational opportunity.”

Emory cast the only dissenting vote. Commission member Suzanne Dorsey abstained from voting but agreed with Emory that a longer-term forecast would “add value to individual, local and statewide decision-making.”

‘More practical’

Charles “Pete” Peterson, a scientist with the UNC Institute of Marine Sciences and a panel member, said later that it would be “crazy” to propose regulations based on a 100-year forecast, because scientists are not as confident as that single 39-inch number suggested.

A 30-year forecast “might be easy for us to do,” Peterson said. “It doesn’t carry an educational role, like the original one did. But it may be more practical.”

Gorham said he will fill vacancies on the science panel in a few weeks.

A parallel study ordered by the legislature, to assess the likely costs or benefits of any new policies related to sea level, will get under way later, Gorham said.

“I think we need to make some decisions about sea-level rise,” Gorham said. “If you have a 30-year period, people will take it more seriously.”