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East Coast Vulnerable to Sea Level Rise

21 Jan

A recent feature article in the New York Times (here) documents just how vulnerable the U.S. East Coast is to flooding from sea level rise. This hazards come not only from the gradual rise of ocean levels connected to global warming but also because large areas from southern Maine to the Chesapeake Bay region are actually sinking.

The U.S. East Coast is increasingly vulnerable to flooding because the combination of sea level rise associated with global warming and also because large areas of the region are actually sinking as underlying sediments compress. (AP Photo)

The U.S. East Coast is increasingly vulnerable to flooding because the combination of sea level rise associated with global warming and also because large areas of the region are actually sinking as underlying sediments compress. (AP Photo)

Here are excepts from the NY Times article:

“Much of the population and economy of the country is concentrated on the East Coast, which the accumulating scientific evidence suggests will be a global hot spot for a rising sea level over the coming century.The detective work has required scientists to grapple with the influence of ancient ice sheets, the meaning of islands that are sinking in the Chesapeake Bay, and even the effect of a giant meteor that slammed into the earth.

The work starts with the tides. Because of their importance to navigation, they have been measured for the better part of two centuries. While the record is not perfect, scientists say it leaves no doubt that the world’s oceans are rising. The best calculation suggests that from 1880 to 2009, the global average sea level rose a little over eight inches. That may not sound like much, but scientists say even the smallest increase causes the seawater to eat away more aggressively at the shoreline in calm weather, and leads to higher tidal surges during storms. The sea-level rise of decades past thus explains why coastal towns nearly everywhere are having to spend billions of dollars fighting erosion. The evidence suggests that the sea-level rise has probably accelerated, to about a foot a century, and scientists think it will accelerate still more with the continued emission of large amounts of greenhouse gases into the air. The gases heat the planet and cause land ice to melt into the sea. The official stance of the world’s climate scientists is that the global sea level could rise as much as three feet by the end of this century, if emissions continue at a rapid pace. But some scientific evidence supports even higher numbers, five feet and beyond in the worst case…..

Scientists say the East Coast will be hit harder for many reasons, but among the most important is that even as the seawater rises, the land in this part of the world is sinking. And that goes back to the last ice age, which peaked some 20,000 years ago. As a massive ice sheet, more than a mile thick, grew over what are now Canada and the northern reaches of the United States, the weight of it depressed the crust of the earth. Areas away from the ice sheet bulged upward in response, as though somebody had stepped on one edge of a balloon, causing the other side to pop up. Now that the ice sheet has melted, the ground that was directly beneath it is rising, and the peripheral bulge is falling. Some degree of sinking is going on all the way from southern Maine to northern Florida, and it manifests itself as an apparent rising of the sea. The sinking is fastest in the Chesapeake Bay region. Whole island communities that contained hundreds of residents in the 19th century have already disappeared. ”

Again, you can read the complete article, as well as see the maps and photos, here.

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Posted by on January 21, 2014 in Global Environment, North America

 

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