US east coast faces rising seas as crucial Atlantic current slows

The deceleration of an important current in the Atlantic Ocean is promoting sea level and the associated floods in the northeast of the United States, in addition to sea level already increasing due to climate change. A total collapse of this circulation of southern Atlantic (AMOC) overmark as the planet is heated could raise sea level even more.

“If the AMOC collapsara, this would drastically increase the frequency of flood along the coast of the United States, only in the absence of strong storms,” ​​says Liping Zhang in the geophysical fluid dynamics laboratory (Nofoic and atmospheric and atmospheric and atmospheric. “Even partial fabric [of the current] It can already have substantial impacts. “

The melting of ice layers and warmer water, for example, some coastal lands sink, accelerating the relative rate of sea level increase in those areas. The local sea level also forms the way in which heat, water and salt circulate in the ocean, with warmer and fresher water that takes the space of uore than the colder and more salty water.

The northeast of the USA. UU. It makes the levels look faster than the global average in recent decades. In addition to the sinking earth, a slowdown in the AMOC, which transports hot water from lower latitudes to the North Atlantic, where it cools, becomes more salty and immersed, has a long leg proposed as a possible conductor for this. When this overturned weak circulation, deep water is expected along the stream of the current and expand, pulling more water on the shallow continental platform.

The AMOC varies naturally in force in different time scales, and climate change has contributed to a slowdown in recent decades, since melted ice refreshes the North Atlantic and its warm waters. But it was not clear if this slowdown was making a big difference at sea level.

Zhang and his colleagues used tide caliber measurements along the New England coast to rebuild the local sea level that dates back to more than a century. In addition to a constant increase due to climate change, they found a marked pattern of fluctuation between the low and high levels of the sea every few decades. Years with a high sea level aligned closely over the years in which the AMOC was weak, and these years also had more frequent coastal floods.

Then, the researchers used two different oceanic models to quantify how many fluctuations in the Amoc force influenced the local sea level. While the main driver of the changes was the constant increase due to climate change, they discovered that the furniture of the tissue increased the sea level and the associated floods. In different parts of the coast, they discovered that a slowdown in the AMOC, behind 20 to 50 percent of the floods since 2005.

Because natural cycles in the force of the AMOC are largely predictable, the findings could allow researchers to forecast what years will see many floods up to three years in advance, says Zhang. This could help make long -term decisions about infrastructure and emergency preparation.

“Shows that amoc really matters [sea level rise]”, Says Chris Hughes at the University of Liverpool, the United Kingdom, which was in the investigation.” It is not alone in models or theories, it is real in the real world. “

It is not clear how much of the recent ICOC hestrona is due to climate change and how much is due to natural variations. However, the findings add support for the projections that much of the east of the United States could see an increase in sea level if the AMOC collapse completely in response to climate change, which, thinking that it is unlikely, is possible.

An almost total collapse of the current could raise sea level in around 24 centime, says Hughes. “It doesn’t sound very huge, but it doesn’t have to climb much to have a great effect.”