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New research shows that the Arctic Ocean began to warm up decades earlier than previously thought



He to study, published Wednesday in the journal Science Advances, found that the expansion of warm water from the Atlantic Ocean flowing into the Arctic, a phenomenon known as “Atlantification,” has caused Arctic water temperature in the region studied. a increase by about 2 degrees Celsius since 1900.

Francesco Muschitiello, author of the study and assistant professor of geography at Cambridge University, said the findings were worrisome because early warming suggests there may be a flaw in the models scientists use to predict how it will change. the climate.

“The Arctic Ocean has warmed for much longer than we thought,” Muschitiello told CNN. “And that’s something that’s a little disturbing for a lot of reasons, especially because the climate models we use to make projections of future climate change don’t really simulate that kind of change.”

Researchers used marine sediments in the Fram Strait, where the Atlantic meets the Arctic in eastern Greenland, to reconstruct 800 years of data that draw a longer historical picture of how the water in the ‘Atlantic has flowed into the Arctic. Marine sediments are “natural archives,” the researchers wrote, which record data on past weather conditions.

Researchers found that temperature and salinity, the salinity of ocean water, remained fairly constant until the 20th century, and then suddenly increased.

“Reconstructions suggest a substantial increase in heat and salt transport from the Atlantic Ocean to the North Sea in the early 20th century, which is not well simulated by (climate models),” said Rong Zhang, a senior scientist in fluid dynamics. NOAA geophysicists. Laboratory, which did not participate in the study, told CNN. “It is important to understand the cause of this rapid Atlanticization, as well as the discrepancies between model simulations and reconstructions.”

Muschitiello said it is unclear what role, if any, human-caused climate change played in early Arctic warming, and more research is needed.

“We’re talking about the early 1900s, and by then we’ve already been supercharging the atmosphere with carbon dioxide,” he said. “The Arctic Ocean may be more sensitive to greenhouse gases than previously thought. This will require more research, of course, because we do not have solid control over the actual mechanisms behind this early Atlantification.”

The study notes that changes in the South Atlantic Investment Circulation (AMOC) —A system of currents that moderates temperatures in the northern hemisphere — could have played a role in warming the Arctic. In particular, the AMOC weakened after a cooling-off period that ended in the mid-1800s in the North Atlantic region, which researchers suggest could have led to rapid Atlanticization along the East Fram Strait.
A recent study found that AMOC, often described as a “conveyor belt” that transports warm water from the tropics and redistributes it northward, now shows signs of greater instability due to human-induced climate change. Scientists have warned that a collapse in traffic could lead to a sudden change in weather patterns around the world: colder winters in Europe, changes in monsoons and potentially permanent drought in West Africa.

Rapid warming temperatures in the Arctic have caused sea ice to melt, which in turn causes more warming, while bright white sea ice reflects the sun’s energy, the dark ocean absorbs energy. as heat.

James E. Overland, a NOAA Arctic scientist based at the NOAA Pacific Marine Environment Laboratory in Seattle, said these long-term changes in the North Atlantic, along with the recent loss of sea ice in the Arctic, threaten marine ecosystems.

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“The loss of sea ice and ocean currents has shifted the damping region between the Atlantic Ocean and the Arctic Ocean to something closer to an arm of the central Atlantic,” said Overland, who did not participate. in the studio, on CNN. “Important fisheries and marine mammals are vulnerable to the reorganization of ecosystems from this Atlantic.”

A recent one UN State of Science Report On the climate crisis, it was found that the Arctic will continue to heat up faster than the rest of the planet as humans continue to burn fossil fuels and release greenhouse gases into the atmosphere. In addition, Muschitiello said the Arctic Ocean may experience additional warming due to Atlanticization.

“When I talk to my students I always try to make them aware that the Arctic is warming up very, very quickly and much faster than any other area on the planet,” Muschitiello said. “It’s very disturbing and very worrying, especially because we still don’t have a full understanding of the comments at stake.”

“We’re still slowly learning how the whole system works,” he said. “And my fear is that by the time we solve the problem, it will be too late.”