A weaker Gulf Stream, combined with overall global warming, could mean a lot of trouble for the coast of New England, according to this well-documented story from Weather Underground meteorologist Bob Henson. The New England coast already has been hit hard by storms and surging high water (see the picture of Scituate, Massachusetts, above) in the past few months. Two nor’easters earlier this month produced two of the three highest water levels ever recorded in Boston Harbor, and things could get worse.
A basic problem is that the sea level along the Northeast coast is rising faster than it is elsewhere, largely because of a weakening Gulf Stream. The Stream moves well away from the coast before it reaches Massachusetts, separating the colder water along the coast from warmer water farther offshore. As it slows down, that contrast will weaken and sea levels in New England will rise, in addition to any other increase caused by global warming and melting polar ice. Waters in the Northwest Atlantic are already warmer than normal this year.
Another problem is that climate change can make nor’easters even stronger, apart from anything that’s happening with the sea level. Storms in the northern hemisphere have tended to be more frequent and more intense since 1950. Still, scientists thought the ferocity and frequency of this winter’s nor’easters would be decades away.
The threat to New England will only continue to grow as the sea level supporting any storm surge gets higher over time. Indeed, another 1 ½ inch of surge on top of what hit Boston in Winter Storm Grayson in January would flood 6 percent of the city.