Research shows that the rate of sea level rise along a portion of the East Coast—from Halifax, Nova Scotia to Norfolk, Virginia—is accelerating more rapidly than previously calculated, said Boon. Earlier NOAA estimates gave a constant rate of rise of 4.44 millimeters per year at Norfolk, which would result in an increase of .8 foot in mean sea level there by 2050, said Boon.
However, a review of existing data that applies a quadratic curve to the rate of rise shows an acceleration that’s equivalent to twice that rate, which could result in a two-foot or more increase in Norfolk sea levels by 2050.
Areas farther north than Halifax and farther south than Norfolk don’t show an equivalent change in the rate of acceleration, said Boon. He attributes the difference to a change in ocean circulation—specifically, the Atlantic Meridional Overturning Circulation—that affects the northeast coast of the U.S. and parts of Canada, but that doesn’t extend farther north or south.