[Vision2020] From "Nature Geoscience": Northeast US To Suffer Most From Future Sea Rise

[Ted Moffett]

Northeast US to suffer most from future sea rise By SETH BORENSTEIN, AP
Science Writer Seth Borenstein, Ap Science Writer Sun Mar 15, 2:04 pm ET

WASHINGTON – The northeastern U.S. coast is likely to see the world's
biggest sea level rise from man-made global warming, a new study predicts.

However much the oceans rise by the end of the century, add an extra 8
inches or so for New York, Boston and other spots along the coast from the
mid-Atlantic to New England. That's because of predicted changes in ocean
currents, according to a study based on computer models published online
Sunday in the journal Nature Geoscience.

An extra 8 inches — on top of a possible 2 or 3 feet of sea rise globally by
2100 — is a big deal, especially when nor'easters and hurricanes hit,
experts said.

"It's not just waterfront homes and wetlands that are at stake here," said
Donald Boesch, president of the University of Maryland Center for
Environmental Science, who wasn't part of the study. "Those kind of rises in
sea level when placed on top of the storm surges we see today, put in
jeopardy lots of infrastructure, including the New York subway system."

For years, scientists have talked about rising sea levels due to global
warming — both from warm water expanding and the melt of ice sheets in
Greenland and West Antarctica. Predictions for the average worldwide sea
rise keep changing along with the rate of ice melt. Recently, more
scientists are saying the situation has worsened so that a 3-foot rise in
sea level by 2100 is becoming a common theme.

But the oceans won't rise at the same rate everywhere, said study author
Jianjun Yin of the Center for Ocean-Atmospheric Prediction Studies at
Florida State University. It will be "greater and faster" for the Northeast,
with Boston one of the worst hit among major cities, he said. So, if it's 3
feet, add another 8 inches for that region.

The explanation involves complicated ocean currents. Computer models
forecast that as climate change continues, there will be a slowdown of
the great
ocean conveyor belt. That system moves heat energy in warm currents from the
tropics to the North Atlantic and pushes the cooler, saltier water down,
moving it farther south around Africa and into the Pacific. As the conveyor
belt slows, so will the Gulf Stream and North Atlantic current. Those two
fast-running currents have kept the Northeast's sea level unusually low
because of a combination of physics and geography, Yin said.

Slow down the conveyor belt 33 to 43 percent as predicted by computer
models, and the Northeast sea level rises faster, Yin said.

So far, the conveyor belt has not yet noticeably slowed.

A decade ago, scientists worried about the possibility that this current
conveyor belt would halt altogether — something that would cause abrupt and
catastrophic climate change like that shown in the movie "The Day After
Tomorrow." But in recent years, they have concluded that a shutdown is
unlikely to happen this century.

Other experts who reviewed Yin's work say it makes sense.

"Our coastlines aren't designed for that extra 8 inches of storm surge you
get out of that sea level rise effect," said Jonathan Overpeck, director of
an Earth studies institute at the University of Arizona.

While Boston and New York are looking at an additional 8 inches, other
places wouldn't get that much extra rise. The study suggests Miami and much
of the Southeast would get about 2 inches above the global sea rise average
of perhaps 3 feet, and San Francisco would get less than an extra inch.
Parts of southern Australia, northern Asia and southern and western South
America would get less than the global average sea level rise.

This study along with another one last month looking at regional sea level
rise from the projected melt of the west Antarctic ice sheet "provide a
compelling argument for anticipating and preparing for higher rates of sea
level rise," said Virginia Burkett, chief scientist for Global Change
Research at the U.S. Geological Survey.

Burkett, who is based in Louisiana, said eventually New Englanders could be
in the same "vulnerability situation" to storms and sea level rise as New
Orleans.

___

On the Net
Nature Geoscience: http://www.nature.com/ngeo
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Vision2020 Post: Ted Moffett
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