Collapse of key Atlantic currents may be held off by newly-discovered back-up system, study finds
The keys to the Atlantic Ocean currents which seem to slow down due to climate change Perhaps more resilient to global warming than scientists thought before – thanks to a secret rescue system, according to a new study.
The circulation of southern Atlantic (AMOC) is a network of currents that loops around the Atlantic as a giant treadmill belt. The cold and salty waters flow near Greenland and then travel south along the bottom of the ocean. Finally, these waters go up to the surface near the Antarctica and return north, bringing the more balm waters to the northern hemisphere. This system is crucial to reheating Europe, especially.
In recent years, experts have repeatedly sounded the alarm bellsuggesting step in which sier waters could stop completelyThis could lead to a massive drop in temperatures in northern Europe and exacerbate sea level elevation along the American east coast, Among other impacts.
Researchers think that this crucial step of the AMOC is in difficulty due to changes in the formation of dense water – the process by which the upper layer of the ocean is at the bottom. Cold and salty water is more dense than warmer and less salty water. Under normal conditions, surface waters lose a lot of heat when they travel through the North Atlantic, which makes them flow when they reach the end of their trip to the north.
This generally takes place in the Nordic seas – the seas of Greenland, the Norwegian and Iceland – Marius ÅrthunA physical oceanographer at the University of Bergen in Norway and the main author of the new study, told Live Science in an email.
But with climate change cooking the planet, the surface waters of this region no longer transfer as much heat in the air, while the rivers of the cast iron are also arctic And Filo Greenland In the ocean, dilute the salt content of surface waters and prevent them from flowing.
In relation: The key Atlantic current weakens much faster than scientists had predicted it
The formation of dense water in the Nordic seas has decreased since 1993, which has expressed problems for the entire Atlantic circulation system – without a newly found rescue system, said Årthun. The researchers published their results on Friday July 11 in the journal Scientific advances.
Arctic “Atlantification”
For the study, Årthun and his colleagues have fueled measures of density from the Subpolar North Atlantic, Nordic seas and the Arctic Ocean in a computer model. They compared the results with the observations available to verify that the simulation precisely reflected the processes in this region.
The simulation confirmed that the Arctic Ocean undergoes a process called “Atlantification”.
“Atlantation refers to the transition from the Arctic Ocean of a cold state and covered with ice to a warm and more ice -free state,” said Årthun.
The last decades have seen sea ice in the Barents Sea – an Arctic Ocean region located between Scandinavia and Svalbard – Retraite further and further in the northSaid Årthun. “We expect the Barent Sea to be the first Arctic region to become without ice,” he said, adding that Atlantic waters are now also broadcasting In the Eurasian basin, north of the Barents Sea.
The Atlantification of the Arctic Ocean means that the region creates denser water than it was before, said Årthun.
“We note that this decrease [in dense water formation] In the Nordic seas, was offset by a denser water formation in the Barents Sea and north of Svalbard, “he said.” These two regions have experienced a retired sea ice edge […]Hence the increase in the area on which dense waters can be produced. “”
The authors believe that this backup system could help support the Amoc. “There are processes that add resilience to amoc, which may make a weakening or a serious collapse,” said Årthun.
Additional research is necessary to determine if this backup system will last in a world of warming. There is also a question mark on how the Arctic Ocean can really replace the Nordic seas by forming extremely dense water, says Nicholas FoukalA physical oceanographer and assistant professor at the University of Georgia who was not involved in the study.
It would be interesting to explore whether the densest waters are still formed, said Foukal live in an email, because “the water masses that were formed historically in the Greenland Sea were incredibly dense”.
The Greenland Sea is a very deep ocean basin which is exposed to the icy gusts of the Greenland ice cap. “The Arctic does not have this type of adjustment,” said Foukal. “I doubt that these really dense waters are formed in the Arctic.”
