The American East Coast faces the height of the seas, as the decisive Atlantic current stream slows down

The slowdown in the Atlantic Ocean enhances sea level and its associated floods in the northeastern United States, as well as already high sea level due to climate change. A complete collapse of this transmitted blood circulation (Amoc) where the planet’s temperature can raise sea level to the sea level.

“If the Amoc collapses, this will greatly increase the frequency of the flood along the American coast, even in the absence of strong storms,” ​​he says. Pits Chang In the geophysical fluid dynamics laboratory in the National Administration and Air Country (NOAA) in New Jersey. Even partial weakness [of the current] It can already have significant effects. “

The melting of the most warmer ice and water panels due to the climate change that a person causes leads to a high sea level, but the average sea level level is not the same everywhere. For example, some coastal lands are drowned, which speeds up the relative rate of sea level rise in those areas. Local sea level is also formed by how to rotate heat, water and salt in the ocean, with warmer water and livelihood of colored cold water.

He saw the northeastern coast Sea surface levels rise faster From the global average in recent decades. In addition to the drowning of the Earth, a slowdown in Amoc – which transports warm water from the lower latitude to the North Atlantic Ocean, has been suggested, and it has become more salty and drains – long ago as a possible engine for this purpose. When this blood circulation weakens, the deep water is expected to heat and expand the current, and slide more water on the shallow continental shelf.

Amoc naturally differs in strength at different time periods, and climate change has contributed to slowing in recent decades with ice melting in the North Atlantic Ocean and its warm waters. But it was not clear whether this slowdown made a big difference in sea level.

Zhang and its colleagues used the tidal scale measurements along the New England coast to rebuild the local sea level that extends to more than a century. In addition to a fixed height due to climate change, they found a remarkable pattern of fluctuations between low and high sea levels every few decades. Years with sea level rise in line closely with years when Amoc was weak, and these years were also more frequent coastal floods.

Then the researchers used two different models of the oceans to determine the amount of fluctuations in the Amoc power that affected the local sea level. While the main engine of changes was the steady height due to climate change, they found that Amoc has greatly strengthened sea level and the floods associated with them. In different parts of the coast, they found that the slowdown in Amoc was behind 20 to 50 percent of the floods since 2005.

Since the natural courses in the Amoc power can be largely predictable, the results can enable researchers to predict the years that will witness many floods three years ago, says Zhang. This can help take long -term decisions about infrastructure and emergency preparedness.

It explains that amoc is really important [sea level rise]He says Chris Hughes At the University of Liverpool, the UK, which has not participated in the research. “Not only there in models or theory, they are already in the real world.”

It is not clear the last weakness of Amoc due to climate change and the amount of natural changes. However, the results add support to expectations that a lot of the American eastern coast can see an increase in sea level if Amoc has completely collapsed in response to climate change – which is possible, although it is unlikely.

Hughes says that the almost currently based on the surface -based collapse can raise the sea level by about 24 cm. “This does not seem very huge, but it is not necessary to have a great effect.”

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