New study offers more fodder for sea-rise debate

By on June 27, 2012

By Frank Tursi
Coastal Review Online

With state legislators still wading through the issue of rising seas, a new federal report seems to further muddy the water.

Contrary to what we heard from some legislators the past few weeks, not only does the sea seem to be rising along the state’s northern coast, but it’s doing so at a rate three or four times faster than anyplace else in the world.

That, at least, is one of the conclusions of a new study of sea-level rise that the U.S. Geological Survey published Sunday in the journal Nature Climate Change.

Analyzing information from tide gauges along the north and mid-Atlantic coasts, agency researchers found that sea level along a 600-mile stretch, from Cape Hatteras to north of Boston, has increased 2 to 3.7 millimeters a year, starting around 1990. That’s as much as 2.75 inches during that span. The average global increase over the same period was 0.6 to 1.0 mm. a year, or about three-quarters of an inch total, the study notes.

If global temperatures continue to increase this century because of global warming, the Atlantic Ocean in this region is expected to continue to rise at a faster rate than it will elsewhere, the researchers said. The sea along this stretch of coast, which contains some of the country’s largest metropolitan areas and most densely populated coastal landscapes, could rise 8 to more than 11 inches higher than the global average by 2100, the research showed.

It’s not just a faster rate, but at a faster pace, like a car on a highway “jamming on the accelerator,” Asbury Sallenger Jr., an oceanographer at the agency and the study’s lead author, told the Associated Press.

Seas will rise gradually over time, noted Peter Howd, an oceanographer under contract with the USGS and one of the paper’s other authors, but greater flooding from winter storms will be the first signs.

“People are starting to recognize that winter storms that used to pass by without producing any flooding, all of sudden they are getting flooding,” Howd said in an interview last week. “Where it’s really going to hit home is that the storms that we get 3 or 4 times a winter will start looking like the storms that we get every 3 or 4 years.”

Science and politics

The new research seems to counter arguments made by backers of a bill that passed the N.C. Senate a couple of weeks ago. The bill was widely interpreted as preventing the state from using the latest scientific modeling when planning for future sea-level rise because of global warming.

Warming atmospheric temperatures in the future are expected to push up sea levels by melting ice sheets in Greenland and west Antarctica. Because warmer water expands, climatologists use sophisticated computer models to predict how high the seas could get under different warming scenarios.

After reviewing the consensus of those models, a panel of scientific advisers told the state Coastal Resources Commission in 2010 to prepare for a sea-level rise of 39 inches by 2100, or more than triple the historic rate. Though the new research suggests adding a few more inches to that total, the forecast was in line with those made by major scientific organizations around the world and by several countries and other states.

But the state report immediately came under fire from development interests and some coastal counties. They feared that regulations to protect against such a drastic rise in sea level would stifle economic growth on the coast.

Critics also questioned the science behind the report. That was echoed by sponsors of the Senate bill. The science of sea-level rise was unsettled, they said, and the models were speculative at best. Credible evidence exists, they insisted, that indicates sea levels haven’t risen appreciably in the past 100 years.

The bill that passed the Senate would have forced the state to use those historic rates when planning for what the ocean might do in the future. Those long-term average rates of historic sea-level rise, when extrapolated into the future, indicate the ocean might rise only 8 inches this century, not 39.

After being lampooned by commentators, scientists and writers around the world, the bill died last week when the N.C. House refused to vote on it. Representatives from both chambers are trying to devise a compromise.

The names of Robert Dean and James Houston came up often in the debate. They are well-respected coastal engineers who studied data from tide gauges and determined that long-term average sea-level rise for the past 80 years has been negligible even though temperatures have risen.

The USGS researchers tried to replicate Dean and Houston’s findings by using the same tide information from across North America, Howd noted. To determine if the rate of rise has recently accelerated, though, they analyzed smaller time segments of tide gauge data and in a way that removed long-term trends associated with vertical land movements.

“Dean’s numbers are correct for what he calculated, the long-term average acceleration over the last 80 years,” Howd explained. “That’s a very different answer as to whether there’s any recent acceleration. We just asked a different question.”

AMOC and you

This is the Atlantic meridional overturning circulation, or AMOC.This great conveyor belt could be affected by global warming, causing among other things rising seas along the northern N.C. coast.

The answer they got has everything to do with the Atlantic meridional overturning circulation, called AMOC by those who study such things. It’s part of the oceans’ conveyor system, which constantly redistributes heat and cold. AMOC carries warm water from the tropics to high northern latitudes near the surface and returns cold water from the north Atlantic in the deep ocean to the Southern Hemisphere. In that way, a balance is achieved. The Gulf Stream is AMOC’s main highway north.

How AMOC does all this is complicated, involving water temperature, salinity and density in the subpolar north Atlantic, but scientists have long thought that a warming climate could affect the circulation. The USGS study, though, may be the first to indicate that might be happening already. The report shows that the sea-level rise “hotspot” north of Cape Hatteras is consistent with the slowing of AMOC, Howd said.

So much water is flowing north in the Gulf Stream and at such a quick pace that the core of the stream is two meters higher than the water at the shoreline, Howd explained. “When the current slows down, the Gulf Stream falls and the water levels increase at the coast. That’s the simple answer, but it’s pretty complicated.”

The magnitude of this see-saw affect will be greater farther from the Gulf Stream, Howd said. The Stream hugs the N.C. coast before veering east across the Atlantic north of Cape Hatteras. Howd and the other researchers saw no evidence of accelerated sea-level rise above the global average for much of the state’s coast. It became evident north of the cape, he said, but the rate there was lower than it was farther north.

Because of its proximity to the Gulf Stream, the northern N.C. coast could expect to see seas rise at the low end of the study’s estimates, about 8 inches above the global average by 2100, Howd said.

Whatever the they do in the future, the oceans won’t do it at the same rate in every location, noted Marcia McNutt, the director of the USGS. Differences in land movements, strength of ocean currents, water temperatures and salinity can cause regional and local highs and lows in sea level.

“Many people mistakenly think that the rate of sea-level rise is the same everywhere as glaciers and ice caps melt, increasing the volume of ocean water, but other effects can be as large or larger than the so-called ‘eustatic’ rise,” she said. “As demonstrated in this study, regional oceanographic contributions must be taken into account in planning for what happens to coastal property.”

And it may not take years to feel the effects of rising seas, Sallenger said.

“Cities in the hotspot, like Norfolk, New York and Boston already experience damaging floods during relatively low-intensity storms,” he said in a press release. “Ongoing accelerated sea-level rise in the hotspot will make coastal cities and surrounding areas increasingly vulnerable to flooding by adding to the height that storm surge and breaking waves reach on the coast.”

This story is provided courtesy of Coastal Review Online, the coastal news and features service of the N.C. Coastal Federation. The Outer Banks Voice is partnering with Coastal Review Online to provide readers with more stories of interest in our area. You can read other stories about the N.C. coast at www.nccoast.org.

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Comments

ComfortablyBum

July 5, 2012 8:56 pm

If publishing articles like this removes the Glen Beck trolls from the comment section, then I say publish more.

We are already seeing the results of climate change, the only people who don’t see it have their heads in the sand or in the echo chamber that is the conservative internet. Between Drudge Report and e-mail forwards, they never have to hear someone they disagree with. Then they just keep yabbering on like they know what they are talking about and insulting anyone who isn’t fooled by the same garbage they are.

ekim

June 30, 2012 11:26 am

Peeps dont let these LIBERALS bring you down! MORRIS is a true believer in this CRAP! thats why he runs these stories if you look at the history of the Voice Morris has supported every tax hike that comes our way!

B.ill

June 29, 2012 9:04 am

I don’t mind the article, I mind that most people seem to read the head lines not the article. This survey is not fodder… fodder is something bulls can eat. This article came from the other end of the bull.

It also bothers me that sound science is seemingly being trumped by any fool with an agenda and a “computer model”. I see these “studies” as yet another climatologist on the on ramp of life holding a piece of cardboard… “will science for food”.

junkman

June 29, 2012 8:19 am

“…a new federal report seems to further muddy the water.”
WHAT ? This report seems to further confirm the prevailing science on this issue and should be yet another wake up call,although the NC Senate is obviously sound asleep.

The only muddy water we’ll see will be in our living rooms.

Ekim

June 29, 2012 7:35 am

Anyone that believes this bull*!%# please sell me your prop an head to high ground!

Sue

June 28, 2012 9:26 pm

Prince, why not read from a multitude of different news sources? It’s really the only way to look at all facets of a situation and draw your own conclusions. By the way, this particular story has been “hot” all over the place for the past week now. Anyway, the same holds true with these comment sections that actually act more like forums sometimes. Multiple viewpoints are presented, giving people more to think about. How boring it would be if everybody agreed on everything!!

Rob Morris

June 28, 2012 3:38 pm

Prince — I think your objection should be with the U.S. Geological Survey. Every paper in the country wrote about this report. Reporting what it says doesn’t equate with agreeing with it.

chaser

June 28, 2012 3:11 pm

simpleman…conspiracy much?

Prince of Peeps

June 28, 2012 2:39 pm

This will be my last visit and post to the Voice. I didn’t start coming here to read Coastal Review biased BS.

simpleman

June 28, 2012 11:42 am

Sea level rise and climate change.The scientist are split on it.More storms probably.But take a look at the big picture.Check out “weather as a force multiplier:owning the weather in 2025″.And “weather modification”.There is more to it than global warming.Your Meteorologist will not tell you the whole truth on the record.But off record is a different story.They are doing “solar radiation management” spraying on the OBX today.Painting our skies white.To reduce sunlight by 30%.The scientist do not know the problems or reactions in might cause down here on our sandy shores.Anything you put in the big swimming pool {ocean}will make the level rise.Lot of stuff in the oceans now from Japans mega storm.By the way trillions of gallons of water are removed from the ocean everyday for consumer water use.That will increase as inland fresh water disappears.Be more worried about the air pollution you breathe.From the chemicals those tankers are spraying.

chaser

June 28, 2012 8:09 am

And the rest of the world looks at the US and says no wonder you guys are ranked in 27th in the world in science and math.

MichaelAP5

June 28, 2012 8:07 am

I don’t know. There’s a lot of “science” here. I think we should ignore the science of actually measuring something and just “say” that that the sea level is not rising. Better yet, let’s “say” that the sea level in N.C. is actually receding. The Senate will surely back us up. Think what that will do for real estate values!

B.ill

June 27, 2012 10:39 pm

Jeeze Louise, what are these “scientists” thinking? The dikes protecting one property cause another property to flood. Ask the people in the Mississippi flood plain… they know.

The same works for the ocean, Mirlo would had not have flooded near as bad as it did if the dunes were not artificially built up into dikes. What would have been a couple of inches every where turned into a new inlet where the dike blew out.

Was I the only person that saw that the level of the water did not increase appreciably but the flooding did?

Relevant quote is “…determined that long-term average sea-level rise for the past 80 years has been negligible even though temperatures have risen.”

Apparently global warming is causing land to sink. Relevant quote is “…they analyzed smaller time segments of tide gauge data and in a way that removed long-term trends associated with vertical land movements.”

Someone needs to grab these agenda 21 yahoos by the scruff of their necks and toss them out on their keisters.

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