April 25 2018
Scientists believe that currents flowing through the Atlantic have never been so weak and unpredictable since the fifth century. The phenomenon is also added to the melting of the pack ice, which pours millions of tons of fresh water into the sea.
These two combined effects have an influence on the Atlantic Ocean and call into question the circulation of waters between the hemispheres. North and South.
Because of the increasingly violent confrontation between bodies of water whose salinity and temperature are more and more different, a part of the warm waters moves towards the depths and returns to the South, a phenomenon the scientists call "the returning meridian circulation of the Atlantic".
According to researchers at the origin of these studies, it is because of this phenomenon that the Gulf Stream is weakening: it is in fact no longer sufficiently cooled and its salt density decreases.
These problems have been noted for several years now, but as Stefan Rahmstorf, a researcher at the Polish Institute in Potsdam, explains, "we now have certainties [...] We have analyzed all the temperature data sets of the surface of the sea available, including data from the late nineteenth century to the present day. The model we found in the measurements looks exactly like what is announced by computer simulations, namely a slowdown in the Gulf Stream."
The authors of the second study, conducted by David Thornalley's team at the University of London College, explain that the Gulf Stream and other currents important to global equilibrium have changed in the last fifty years, "certainly, during the twentieth century, with a notable decline from 1950 [...] This evolution is surely linked to human factors."
David Thornalley also believes that the change in currents, including the Gulf Stream, "represents a decrease of 3 million cubic meters of water per second, the equivalent of a dozen rivers like the Amazon. And I think that's very bad news. "