A new study by the Woods Hole Oceanographic Institution (WHOI) clarifies what influence major currents in the North Atlantic have on sea level along the northeastern United States. The study, published June 13 in the journal Geophysical Research Letters, examined both the strength of the Atlantic Meridional Overturning Circulation (AMOC)—a conveyor belt of currents that move warmer waters north and cooler waters south in the Atlantic—and historical records of sea level in coastal New England.
“Scientists had previously noticed that if the AMOC is stronger in a given season or year, sea levels in the northeast U.S. go down. If the AMOC weakens, average sea levels rise considerably,” says Chris Piecuch, a physical oceanographer at WHOI and lead author on the paper. “During the winter of 2009-2010, for example, we saw the AMOC weaken by 30 percent. At the same time, sea level in our region rose by six inches. That doesn’t sound like a lot, but a half-foot of sea level rise, held for months, can have serious coastal impacts.”
“But, it’s been unclear whether those two things—coastal sea level and the AMOC—are linked by cause and effect,” adds Piecuch. Although the study confirmed that AMOC intensity and sea level seem to change at the same time, it found that neither directly causes changes in the behavior of the other. Instead, both seem to be controlled simultaneously by variability in major weather patterns over the North Atlantic, such as the North Atlantic Oscillation (NAO).
Read more at Woods Hole Oceanographic Institution
Illustration by Natalie Renier, Woods Hole Oceanographic Institution