Sea Levels Spiked for Two Years on the Northeast Coast--And May Rise Again

It turns out that there was a four-inch increase in sea levels stretching from New York to Newfoundland in 2009 and 2010 due to a change in ocean circulation. The findings reveal that an extreme increase in sea level rise can last for years rather than just months.

"The thing that stands out is the time extent of this event as well as the spatial extent of the event," said Paul Goddard, one of the researchers, in a news release.

Although four inches may not seem like a lot, it's enough to cause floods. In fact, independent of any hurricanes or winter storms, the event caused flooding along the northeast coast of North America. Some of the sea level rise and the resulting flooding extended as far south as Cape Hatteras.

The scientists first detected this spike in sea levels by reviewing monthly tide-gauge records, some of which date back to the early 1900s, for the entire Eastern Seaboard. This revealed that the two years had a marked increase in levels.

So what caused this rise? It turns out the spike was due to a change in the ocean's Atlantic Meridional Overturning Circulation. It was also due to a change in part of the climate system known as the North Atlantic Oscillation.

"The negative North Atlantic Oscillation changes the wind patterns along the northeast coast, so during the negative NAO the winds push water onto the northeast coast," said Goddard.

As levels of carbon dioxide increase in the atmosphere, it's likely that these extreme events will actually occur more frequently. Even now, the sea level is still higher than before 2009.

The findings are published in the journal Nature Communications.

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