circulation Atlantic Meridian Current (AMOC)English), an oceanic flow system that carries warm water from the tropics to the North Atlantic and cold water from the northern hemisphere to the south, This is a fundamental mechanism for regulating the Earth’s climate.. This ‘conveyor belt’ has come to a standstill in the distant past due to natural factors, with serious global consequences. In fact, the most recent collapse played an important role in reducing the last glaciation. Now, AMOC is now threatened by global warming, the scientists showed. The consequences for the climate could be significant.
The study was carried out by German researchers and Brazilian paleoclimatologist Cristiano Mazur Chiessi, a professor at the University of São Paulo (EACH-USP) in Brazil, and the results are published in the journalism. Nature Communication.
This giant conveyor belt carries warmer surface water from the South Atlantic to the North Atlantic. There, this surface water does two things: it gives heat to the cold atmosphere, and it also gets heavier and sinks deeper into the ocean. The deeper it goes, the colder and denser the water becomes, and then it flows south again, traversing nearly the entire planet until it reaches around Antarctica. There this enormous flow rises to the surface again, where it heats up, loses its density and completes the circulation.
But the South Atlantic Current not only carries large volumes of water, about 18 million cubic meters per second. It also carries a huge amount of energy.That’s roughly 100,000 times the equivalent of what Itaipu, the world’s second largest hydroelectric power station on the border of Brazil and Paraguay, produces. The spatial distribution of this energy affects the climate in various parts of the planet.
While the strong and stable circulation of AMOC maintains the global climate as we know it, its slowdown causes a marked shift in energy, upsetting global climatology.
It’s already happened in the past
In fact, you can see what the consequences of this slowdown will be by looking at what happened in the past.
The AMOC came to a standstill several times during the last glacial period, between 71,000 and 12,000 years ago.. Studies based on analysis of marine sediments collected between the Venezuelan coast and northeastern Brazil show that these depressions caused a drastic increase in precipitation in northeastern Brazil and a drastic drop in precipitation in Venezuela and the extreme north of the Amazon. A decrease in precipitation was also reported in the tropics of North Africa and Asia.
It was also discovered that After the North Atlantic seafloor warmed at high latitudes, a massive release of icebergs into the sea occurred. in Canada and the USA. This allowed the researchers to establish the sequence of events responsible for the collapse of AMOC.
The enormous amount of fresh water added to the sea by the melting of icebergs changed the composition of the ocean at the high latitudes of the northern hemisphere. This has had a tremendous impact on the global climate, as the region between Canada and Greenland is a particularly sensitive part of the AMOC.
This is what happens when the AMOC current is slowed down
“The process begins with a seemingly insignificant weakening of the AMOC causing submarine warming in the high latitudes of the North Atlantic. This warming is melting the seawater mouths of the glaciers, moving them rapidly out to sea and releasing huge fleets of icebergs. As the icebergs melt, the salinity of the surface waters in the region decreases. Surface water is not dense enough to sink, so AMOC settles.“Mazur Chiessi explained.
And indeed, monitoring of AMOC in recent years shows that it has weakened. There are three main causes: intensification of precipitation in the high latitudes of the North Atlantic; melting of the ice sheet over Greenland; and warming of the planet’s surface. But whatever the reason, these three possibilities are relates to increased levels of greenhouse gases in the atmosphere due to human activity.
This latest discovery shows that a weaker AMOC would cause abnormal warming of the seafloor in the high latitudes of the North Atlantic, which would melt glaciers in Greenland. As a last resort, this could lead to the collapse of AMOC, which will exacerbate the climate crisis. Scientists are coming to a conclusion that has important repercussions.
Reference work: https://www.nature.com/articles/s41467-022-31754-x#Fig1
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