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Melting glacier threatens US
Source: Agencies |
May 29, 2009, Friday
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NEW York, Boston and other cities on North America's northeast coast could face a rise in sea level this century that would exceed forecasts for the rest of the planet if Greenland's ice sheet keeps melting as fast as it is now, researchers said on Wednesday.
Sea levels off the northeast coast of North America could rise by 30 to 50 centimeters more than other coastal areas if the Greenland glacier melt continues to accelerate at its present pace, the researchers reported.
This is because the current rate of ice-melting in Greenland could send so much fresh water into the salty north Atlantic Ocean that it could change the vast ocean circulation pattern sometimes called the conveyor belt. Scientists call this pattern the meridional overturning circulation.
"If the Greenland melt continues to accelerate, we could see significant impacts this century on the northeast United States coast from the resulting sea level rise," said Aixie Hu, lead author of an article on the subject in the journal Geophysical Research Letters.
"Major northeastern cities are directly in the path of the greatest rise," said Hu, a scientist at the National Center for Atmospheric Research in Boulder, Colorado.
This is an even bleaker assessment than an earlier study indicated. A March article in the journal Nature Geoscience said warmer water temperatures could shift ocean currents so as to raise sea levels off the northeast coast of the United States by about 20cm more than the average global sea level rise.
However, this earlier research did not include the impact of melting Greenland ice, which would speed changes in ocean circulation and send some 10cm to 30cm of water toward northeastern North America, on top of the average global sea level rise.
That could put residents of New York, Boston and other cities at risk since these cities and others lie close to sea level now, Hu said in answer to e-mailed questions.
Not only would coastal residents be at direct risk from flooding but drainage systems would suffer as salty ocean water would move back into river deltas, changing the biological environment, Hu wrote in an e-mail.
"In a flooding zone, because the higher sea level may impede the function of the drainage system, the future flood may become more severe," he wrote. If cities are prone to subsidence higher sea levels would also make that problem worse, according to Hu.
Sea levels off the northeast coast of North America could rise by 30 to 50 centimeters more than other coastal areas if the Greenland glacier melt continues to accelerate at its present pace, the researchers reported.
This is because the current rate of ice-melting in Greenland could send so much fresh water into the salty north Atlantic Ocean that it could change the vast ocean circulation pattern sometimes called the conveyor belt. Scientists call this pattern the meridional overturning circulation.
"If the Greenland melt continues to accelerate, we could see significant impacts this century on the northeast United States coast from the resulting sea level rise," said Aixie Hu, lead author of an article on the subject in the journal Geophysical Research Letters.
"Major northeastern cities are directly in the path of the greatest rise," said Hu, a scientist at the National Center for Atmospheric Research in Boulder, Colorado.
This is an even bleaker assessment than an earlier study indicated. A March article in the journal Nature Geoscience said warmer water temperatures could shift ocean currents so as to raise sea levels off the northeast coast of the United States by about 20cm more than the average global sea level rise.
However, this earlier research did not include the impact of melting Greenland ice, which would speed changes in ocean circulation and send some 10cm to 30cm of water toward northeastern North America, on top of the average global sea level rise.
That could put residents of New York, Boston and other cities at risk since these cities and others lie close to sea level now, Hu said in answer to e-mailed questions.
Not only would coastal residents be at direct risk from flooding but drainage systems would suffer as salty ocean water would move back into river deltas, changing the biological environment, Hu wrote in an e-mail.
"In a flooding zone, because the higher sea level may impede the function of the drainage system, the future flood may become more severe," he wrote. If cities are prone to subsidence higher sea levels would also make that problem worse, according to Hu.
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