US East Coast is facing rising sea as crucial Atlantic current is slowing down

The demolition of a larger current in the Atlantic increases the sea surface and associated floods in the northeastern United States at the top of the already rising sea surface due to climate change. A total collapse of this Atlantic Meridional Ort -Duty Traffic (AMOC) as the planet heats could further raise the sea surface.

“If AMOC collapsed, this would dramatically increase the flood frequency along the US coast, even in the absence of strong storms,” ​​says Liping Zhang at Geophysical Fluid Dynamics Laboratory in the US National Oceanic and Atmospheric Administration (NOAA) in New Jersey. “Even partial weakening [of the current] Can already have significant effects. “

Melting ice plates and warmer water due to human-pussy climate change leads to an increase in the average sea surface, but the rise in sea level rise is not the same everywhere. For example, some coastal land is sinking, speeding up the relative rate of the sea sled in these areas. Local sea levels are also shaped by how heat, water and salt circulate in the sea, with warmer and fresher water that takes more space than colder, salter water.

The US northeast coast has the sea level increasing faster than the global anxiety in recent decades. In addition to sinking land, a slowdown in AMOC – which carries hot water from lower latitudes to the northern Atlantic, where it is cooled, has been salted and sinks – has long been suggested as a possible driver for this. When this overturning circulation is weakened, deep water is expected along the current to heat and expand and blow up more water on the shallow continental shelf.

Of course, AMOC varies in strength on different time scales, and climate change has contributed to a slowdown in recent decades as melting ice refreshes the northern Atlantic and its Waater’s warmth. But it was not clear where this slowdown made it very different from the sea surface.

Zhang and her colleagues used tidal measurements along the New England coast to rebontruck the local sea level that extends more than a century. On top of a steady increase due to climate change, they found a significant fluctuation pattern between low and high sea level every few decades. Years with a high sea level in line with years when Amoc was weak, and these years also had more frequent flooding of the coast.

The researchers then used two different sea models to quantify how much fluctuations in Amoc’s strength affected the local sea level. While the most important driving force for changes was the stable increase in climate change, they found that the weakening AMOC significantly increased the sea surface and associated floods. In different parts of the coast, they found that a slowdown in AMOC was behind 20 to 50 percent of flood sales 2005.

Becuse the natural cycles in Amoc’s strength are largely predictable, the results can enable researchers to predict which years will see lots of floods up to three years in advance, says Zhang. This can help make long -term decisions about infrastructure and emmergency readiness.

“It shows that Amoc really matters to [sea level rise]”Says Chris Hughes at the University of Liverpool, UK, who was involved in the research.” It’s not just there in models or theory, it’s actually there in the real world. “

It is not clear how much of the recent weakening of AMOC is due to climate change and how much is due to natural variations. However, the results add support to projections that much of the US East Coast could see an increase in sea level, IFOC should completely collapse in response to climate change – which, though unlikely, is possible.

An almost total collapse of the current could raise the sea level by about 24 centimeters, says Hughes. “It doesn’t sound very huge, but it doesn’t have to go up much to have a big effect.”