Mon. Dec 6th, 2021

The 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 temperatures in the region studied. to rise by about 2 degrees Celsius since 1900.

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

“The Arctic Ocean has been warming up for a much longer time than we previously thought,” Muschitiello told CNN. “And it’s something that’s a little disturbing for many reasons, especially because the climate models we use to project projections of future climate change do not really simulate this type of change.”

The researchers used marine sediments in the Fram Strait, where the Atlantic Ocean meets the Arctic east of Greenland, to reconstruct 800 years of data that paints a longer historical picture of how Atlantic water has flowed into the Arctic. The marine sediments are “natural archives,” wrote the researchers, who record data on previous climatic conditions.

Scientists found that temperature and salinity, the salinity of seawater, remained fairly constant until the 20th century – then they suddenly rose.

“The reconstructions indicate a significant increase in Atlantic heat and salt transport into the Nordic Sea in the early 20th century, which is not well simulated by (climate models),” said Rong Zhang, senior researcher at NOAA’s Geophysical Fluid Dynamics Laboratory. who were not involved in the investigation, CNN reported. “It is important to understand the reason for this rapid Atlantification, as well as the discrepancies between the model simulations and the reconstructions.”

Muschitiello said it is not clear how much of a role, if any, man-made climate change played in the early Arctic warming, and more research is needed.

“We are talking about the beginning of the 20th century, and by that time we have already left the atmosphere with carbon dioxide,” he said. “It is possible that the Arctic Ocean is more sensitive to greenhouse gases than previously thought. It will obviously require more research because we do not have a solid grasp on the actual mechanisms behind this early Atlantification.”

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The study notes that changes in the Atlantic Meridional Overturning Circulation (AMOC) – a system of currents that moderate temperatures in the northern hemisphere – could have played a role in Arctic warming. In particular, the AMOC weakened after a period of cooling ended in the mid-19th century in the North Atlantic region, which researchers suggest could have led to rapid Atlanticization along the eastern Strait.
A recent study showed that the AMOC, often described as a “conveyor belt” that transports hot water from the tropics and redistributes it to the north, is now showing signs of further instability due to man-made climate change. Researchers have warned that a collapse in circulation could lead to a sharp shift in weather patterns across the globe – colder winters in Europe, changes to monsoons and potentially permanent droughts in West Africa.

The rapidly warming temperatures in the Arctic have caused sea ice to melt, which in turn causes more warming – while light white sea ice reflects the sun’s energy, dark seas absorb the energy as heat.

James E. Overland, a NOAA Arctic scientist based at the NOAA Pacific Marine Environmental Lab in Seattle, said such long-term changes in the North Atlantic, combined with recent sea ice loss in the Arctic, threaten marine ecosystems.

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“Loss of sea ice and ocean currents has moved the buffer zone between the Atlantic and the Arctic Ocean to something closer to an arm of the central Atlantic,” Overland, who was not involved in the study, told CNN. “Major fisheries and marine mammals are vulnerable to ecosystem change from such an Atlanticization.”

A recent UN state-of-the-science report on the climate crisis showed that the Arctic will continue to heat faster than the rest of the planet as long as humans continue to burn fossil fuels and release greenhouse gases into the atmosphere. On top of that, Muschitiello said the Arctic Ocean could experience further warming due to Atlantification.

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

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

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