Coastal infrastructureN.C. panel releases much-anticipated draft of sea-level rise forecast

Last week, the North Carolina Coastal Resources Commission advisory science panel released its draft copy of sea-level rise forecast for several regions along the North Carolina coast over the next thirty years.

The state’s General Assembly rejected a similar report in 2010 after coastal developers and some Republican legislators claimed that the report was biased. That report warned the state to prepare for a 39-inch sea-level rise by 2100, and it was based mainly on sea-level rise projections from the northern part of the state.

The revised forecast was limited by the General Assembly to thirty years – and it must be updated every five years — and reflects sea-level rise at five tide gauges along North Carolina’s coast (see “N.C. panel to issue sea-level rise forecast to guide coastal, infrastructure development,” HSNW, 15 December 2014; ”N.C.‘rolling’ 30-year sea level rise report gaining support from both sides,” HSNW, 27 June 2014; and “Conflicting views hamper N.C. preparation for sea level rise,” HSNW, 26 March 2014).

The differences between sea levels in the northern and southern coasts of North Carolina are due to shifting geologic masses which are descending at a faster rate in the north. The tectonic shifts are the result of melting glaciers in the last ice age, and the gradual compression of glacier sediments deposited on the state’s northern coast. According to the report, by 2045, the seas will rise between 6.5 and 12.1 inches at Duck, between 4.8 and 11.6 inches at the Oregon Inlet Marina, between 4.9 and 9.3 inches at Beaufort, between 4.1 and 8.5 inches at Wilmington, and between 4.0 and 8.5 inches at Southport.

East Carolina University geologist Stan Riggs, a science panel member, wants state leaders and private developers to begin planning infrastructure projects with the effects of climate change in mind, but a 2012 state law bans state agencies from taking any action based on the sea-level forecast until 1 July 2016.

“If you’re going to build sewage plants or hospitals or highways, you’d better be thinking about the longer term,” Riggs said last Wednesday. “How many mom-and-pop businesses out there [on the Outer Banks] have failed this year because Highway 12 has been broken or under water? It has been happening more frequently, under less-stormy conditions.”

The northern Outer Banks are slowly sinking, notes the News Observer.

The 18-months wait untilstate agencies may take sea-level rise forecast into account may put North Carolina behind other East Coast states which have already begun to adapt to sea-level rise by updating their zoning laws, construction elevation requirements, and major infrastructure plans. Analysts say it will also delay investments in infrastructure, as private businesses may be wary about investing large amounts of money according to current building and zoning codes which will change in summer 2016, when sea-level rise forecasts are factored in, resulting in expansive reconstruction and retrofitting.

As planned, the draft forecast is subject to comments from the public, and a peer review period by two out-of-state sea-level experts, Robert G. Dean, a former civil engineering professor at the University of Florida, and James R. Houston, a former research director with the U.S. Army Corps of Engineers.

In addition to the sea-level forecast report, the Coastal Resources Commission, chaired by Frank Gorham III, is expected to order another report investigating the economic and environmental effects of adopting coastal regulations based on the final sea-level forecast.