Arctic Ocean started warming decades earlier than expected – .

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Arctic Ocean started warming decades earlier than expected – .


Fram Strait in 2009. Source – Algkalv, CC SA 3.0.
The Arctic Ocean has been warming since the turn of the 20th century – decades earlier than records suggest – due to warmer water flowing through the delicate polar ecosystem of the Atlantic Ocean.

The rapid expansion of the Atlantic Ocean into the Arctic Ocean is indisputable proof of the rapid changes taking place in this region.

This so-called “Atlanticization” of the Arctic Ocean caused arctic water temperature in the study region. To increase by about 2 degrees Celsius since 1900, according to a new study published in the journal Science Advances on November 24, 2021.

Francesco Muschitiello, co-author of the study and assistant professor of geography at the University of Cambridge, said the results were concerning as early warming suggests there could be a flaw in the models scientists are using to predict how the climate will change.

“The Arctic Ocean has been warming for much longer than we previously thought,” Muschitiello told CNN. “And that’s something that’s a little unsettling for a lot of reasons, especially because the climate models we use to project future climate changes don’t really simulate these types of changes. “

The international team of researchers came to this conclusion after reconstructing 800 years of data from marine sediments in the Fram Strait, where the Atlantic meets the Arctic east of Greenland.

The precisely dated paleoceanographic records they used were based on organic biomarkers and benthic foraminifera data. Marine sediments are “natural records,” the researchers wrote, which record data on past climatic conditions.

The team’s results show that the Arctic Ocean began to warm rapidly at the turn of the last century, and that this change likely preceded the warming documented by modern instrumental measurements, with records dating back only to about 40 years.

During the study, the researchers found that temperature and salinity, the salinity of ocean water, remained fairly constant for the Arctic Ocean until the 20th century. Since 1900, the ocean temperature has risen by about 2 degrees Celsius, as sea ice has receded and salinity has increased, according to Phys.org.

“The reason for this rapid Atlanticization at the gateway to the Arctic Ocean is intriguing,” said Muschitiello. “We compared our results with ocean circulation at lower latitudes and found that there is a strong correlation with the slowing of dense water formation in the Labrador Sea. ”

“In a future warming scenario, the deep circulation in this subpolar region is expected to decrease further due to the thaw of the Greenland ice sheet. Our results imply that we might expect a further Atlantic Atlanticization in the future due to climate change. “

So what does this study have to do with the accuracy of today’s climate models? The researchers say the study may also reveal a possible flaw in climate models because they do not replicate this early atlantification at the turn of the last century.

Climate simulations generally do not reproduce this type of warming in the Arctic Ocean, which means that there is an incomplete understanding of the mechanisms behind atlantification, ”said Tommaso. “We rely on these simulations to project future climate change, but the absence of any sign of an early warming of the Arctic Ocean is a missing piece of the puzzle. “

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