Sea level rise guesstimates, 2 mm per year for Wilmington

by Kelly Corbett
Wednesday, November 21, 2012

Four speakers addressed the hot topics of sea level rise and climate change during the second session of the North Carolina Beach, Inlet and Waterway Association’s annual conference on Monday, Nov.19, in front of local officials and members of the general public at the Blockade Runner Beach Resort in Wrightsville Beach.

Asbury Sallenger, an oceanographer at the United States Geological Survey’s St. Petersburg Coastal and Marine Science Center, spoke first using his recently published research paper as background to discuss the increase of sea level rise throughout time.

The paper, co-written with Kara Doran and Peter Howard, explained the hot spots for sea level rise along the coast, particularly in a 1,000-kilometer range from Cape Hatteras to Boston, Mass.

“It’s a very localized phenomenon,” Sallenger said.

He said the question is not if acceleration of sea level rise is real, but how long it could last. As far as duration, Sallenger said sea level rise does not appear to be occurring in a cycle.

“The computer models seem to have done a really good job, but they are just computer models,” he said. “What we do is look at the data.”

The real data came from tide gauges ranging from 1950 to 2009.

“There’s more going on than just a uniform sea level rise around the world, a lot more,” Sallenger said.

Tancred Miller, a coastal policy analyst with the North Carolina Division of Coastal Management, shifted the lecture series to the controversy about House Bill 819 in the North Carolina General Assembly, commonly referred to as the sea level rise bill.

“This bill generated a lot of attention,” Miller said.

He said the North Carolina Coastal Resources Commission Science Panel put out its first SLR assessment in 2010 and will deliver its five-year assessment no later than March 31, 2015.

“That’s exactly the same timeline we were on,” Miller said.

The CRC must present reports by March 2016, which is a “seemingly” long time, Miller said, adding that it takes awhile to get together the information including public hearings and comments.

But, Roger Shew, a lecturer in the department of geography and geology at the University of North Carolina Wilmington, disagreed with Miller’s timeline.

“I think we need to be looking at the data very quickly for this,” Shew said.

The estimates of global SLR range from minimums of 20-80 centimeters to maximums of 57-200 centimeters by 2100, Shew said. The Wilmington trend is at 2 millimeters per year.

“Wilmington is different than the northeast,” Shew said. “You can’t have one size fits all.”

To help solve the SLR problem, Johnny Martin, a coastal engineer at Moffatt and Nichol, looked into whether beach renourishment and inlet restoration funding is worth the cost.

Annually, $19 to $20 million is spent on beach renourishment in North Carolina and $30 million is spent on inlet dredging.

The state and local shares range from $30 to $40 million spent annually and is estimated to grow to $70 to $80 million, with federal funds becoming less available for renourishment and dredging projects, he said.

“Is it worth the investment?” Martin asked. “I would say yes.”

With the maximum of $80 million spent in state and local funding and $4.9 billion in returns from beach recreation, private boating, commercial fishing and other factors, the return on investment is 60:1.

If nothing is done, a 50-percent beach width loss would cost $428 million and 5,600 jobs statewide annually.

One of the main potential funding strategies Martin posed was to increase sales tax by 1-2 percent to generate additional revenue.

“The additional money is there,” Martin said.

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