The last house on Holland Island, Maryland, where 360 people lived before tides took over (file picture). Photograph by Astrid Riecken for the Washington Post/Getty Images

Sea level rise on the U.S. East Coast has accelerated much faster than in other parts of the world—roughly three to four times the global average, a new study says.
Calling the heavily populated region a sea level rise hot spot, researchers warn that cities such as Boston, New York, Philadelphia, and Baltimorecould face a more flood-prone future.

(Also see "New York, Boston 'Directly in Path' of Sea Level Rise.")

Sea levels worldwide are expected to rise as global warming melts ice and causes water to expand. Those levels, though, are expected to vary from place to place, due to factors such as ocean currents, differences in seawater temperature and saltiness, and the Earth's shape.

Now it seems scientists have pinpointed just such a variance.

Analyzing tide-level data from much of North America, U.S. Geological Surveyscientists unexpectedly found that sea levels in the 600-mile (1,000-kilometer) stretch of coast from Cape Hatteras (map), North Carolina, to the Boston area climbed by about 2 to 3.8 millimeters a year, on average, between 1950 and 2009.

Global sea level rise averaged about 0.6 to 1 millimeter annually over the same period.

"If you talk with residents of this hot spot area in their 70s or 80s who've lived there all their lives, they'll tell you water is coming higher now in winter storms than it ever did before," said study co-author Peter Howd, an oceanographer contracted with the USGS.

"We're now finally getting to the point where we can measure their observations with our highfalutin scientific instruments."

(Sea sea level rise pictures.)

Flood of Data

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