Gulf Stream is the weakest in 1,000 years; that could drive more Jersey Shore flooding

A slowdown in the Gulf Stream and large Atlantic Ocean currents could bring as much as 2 feet of sea level rise to New Jersey's coast, according to researchers.

Scientists are watching this slowdown in ocean currents, called the "Atlantic meridional overturning circulation," or AMOC, because of the potential for future catastrophic changes to the world, such as precipitously colder western European winters, and major changes in Atlantic-dependent fisheries markets. 

Responsible for warming western Europe and modulating temperatures around the world, AMOC is unlikely to come to a complete stop in the next century, scientists said.

However, recent research indicates an important driver of AMOC, the Gulf Stream, is the weakest it has been in 1,000 years.

"This (ocean currents change) is a factor that will make sea level rise in our region, (but it is) one of a couple of factors that makes sea level rise in our region somewhat higher than the global average," said Robert Kopp, a climate scientist and geobiologist at Rutgers University. "What we most need to be concerned about … is simply that seas, oceans are rising at an accelerating rate. And we're already seeing the effects of that."

Even though there is no evidence the currents will stop any time soon, New Jersey's coastal communities still need to prepare for rising sea levels, Kopp and other experts said.

"If you look at the Jersey Shore, the sort of flooding that happened once every couple years in the 1950s now happens for a week or more in a typical year," added Kopp. "A majority of that can be tied to the effects of … human-caused climate change on sea level rise."

A slowdown in the currents could add another foot of sea level rise rise on top of current sea level rise projections in the coming century, Kopp said. If AMOC stops completely, it could add 2 feet to sea level rise, he said.

That is on top of Rutgers University projections expecting at least 1.3 feet of sea level rise by the end of the century, though moderate projection models predict more than 3 feet of water level increases. Worst-case modeling suggests waters could rise 5 to 8.8 feet from 2000 water levels by the end of the century, according to the university's Climate Change Resource Center.

What will not happen is a "The Day After Tomorrow"-like freeze of the mid-Atlantic states, Kopp said, referring to the 2004 doomsday action movie that portrayed an extreme, fictional global cataclysm resulting from the shutdown of the North Atlantic currents.

"AMOC is not likely to shut down completely in this century… But there is evidence that it may be slowing down now," said Kopp. "Most projections indicate that it will slow down in a warming climate."

Jianjun Yin, an associate professor of geosciences at the University of Arizona who studies ocean currents, sea level rise and climate change, said AMOC appears to be vulnerable to Earth's warming conditions. He, like Kopp, also said a slowdown in the Atlantic currents would raise sea level along the Jersey Shore.

"When the currents along the U.S. Eastern Seaboard move fast and northward, waters are deflected away from the coast due to Earth’s rotation," he said in an email to the Asbury Park Press. "When the currents slow down, this deflection lessons and waters pile up along the coast, causing regional sea level rise. According to model simulations and projections, the slowdown of the AMOC could cause about 20 centimeters (nearly 8 inches) additional sea level rise along the mid-Atlantic over the 21st century."

A slowdown in the currents also could cause New Jersey's coastal waters to warm more quickly, Yin said.

Warm water expands compared to cold water, leading to additional sea level rise, according to the National Oceanic and Atmospheric Administration.

The warming could also harm the Atlantic's marine ecosystem and fisheries off the Jersey Shore, Yin said.

Josh Kohut, a professor of marine and coastal sciences at Rutgers University, said New Jersey's recreational and commercial fishing communities benefit from the biodiversity brought to the region by ocean currents mixing along the state's continental shelf.

Along this shelf, cold New England water currents interact with the Atlantic's warm Gulf Stream and occasionally swirl off into long-lasting water eddies, or circular currents, Kohut said. Those eddies provide nutrient-rich feeding grounds that attract fish and New Jersey's fishing community, he said.

"It's just a really dynamic area, because these eddies can be there. Sometimes they're not there. It just depends on what the Gulf Stream is doing," Kohut said.

Ocean eddies in the North Atlantic play a strong role in concentrating plankton, attracting fish and feeding various species of sharks, according to a 2019 study by the Massachusetts Institute of Technology and the University of Washington.

The eddy boundary zones between warm and cold water are also attractive feeding grounds to marine animals such as tuna, swordfish and squid, according to the Woods Hole Oceanographic Institution, a Massachusetts-based nonprofit organization dedicated to ocean research and exploration.

"If the Gulf Stream were to slow down, as the studies suggests, then that might change the way eddies are formed and how often they form," Kohut said. 

Amanda Oglesby is an Ocean County native who covers Brick, Barnegat and Lacey townships as well as the environment. She has worked for the Press for more than a decade. Reach her at @OglesbyAPP, aoglesby@gannettnj.com or 732-557-5701.