An international group of researchers reconstructed the history of ocean warming in the Fram Strait, which leads to the Arctic Ocean, and found that the ocean has been warming for longer than previously thought. Credit: Sara.
Since the beginning of the 20th century, the ocean has been getting warmer due to warmer water flowing into the polar ocean from the Atlantic Ocean.
A group of researchers reconstructed the history of ocean warming in the Fram Strait, which is the gateway to the Arctic Ocean.
The researchers found that the warming of the Arctic Ocean began at the beginning of the last century as warmer and saltier waters flowed in from the Atlantic, and that this change likely preceeded the warming documented by modern instrumental. Since 1900, the ocean temperature has risen by 2 degrees Celsius, while sea ice has retreated and salinity has increased.
The first historical perspective on Atlantification of the Arctic Ocean and a stronger connection with the North Atlantic has been reported in the journal Science Advances. The connection is capable of shaping the climate variability in the north, which could have important implications for sea-ice retreat and global sea level rise as the polar ice sheets continue to melt.
Climate change is warming all of the world's oceans, but the smallest and shallowest is warming the fastest.
The rate of warming in the northern part of the planet is double the global average due to feedback mechanisms. We know that the ocean has been warming over the past 20 years, but we wanted to place the recent warming into a longer context.
The process oflantification is one of the causes of warming in the northern part of the planet, however instrumental records that can be used to monitor this process, such as satellites, only go back 40 years.
Researchers have found that the ocean began to warm rapidly at the beginning of the last century as warmer and saltier waters flowed in from the Atlantic. Credit: Sara.
The melting of the ice in the polar region is caused by the warming of the ocean. The ocean's surface is exposed to the sun, releasing heat and raising air temperatures. The melting of the permafrost will be more damaging to the environment than carbon dioxide is.
The researchers used data from the ocean to reconstruct the water column properties over the past 800 years. They looked for signs of Atlantification, like a change in temperature, using a combination of methods.
"Our temperature and salinity records look pretty constant when we look at the whole 800-year timescale," said co-lead author Dr. Tesi Tommaso from the Institute of Polar Sciences of the National Research Council in Bologna. At the start of the 20th century, you get a marked change in temperature and salinity.
Muschitiello said the reason for the rapid Atlantification of at the gate of the ocean is intriguing. We found a correlation between the ocean circulation at lower latitudes and the slowdown of dense water formation in the Labrador Sea. The deep circulation in this subpolar region is expected to decrease in a future warming scenario because of the thaw of the Greenland ice sheet. Our results suggest that we might expect more of the same in the future because of climate change.
The researchers say that their results expose a flaw in climate models because they don't reproduce the early Atlantification.
Tommaso said that climate simulations don't reproduce the kind of warming in the Arctic Ocean. The lack of any signs of an early warming in theArctic Ocean is a missing piece of the puzzle, as we rely on these simulations to project future climate change.
Tommaso Tesi, Rapid Atlantification along the Fram Strait at the beginning of the 20th century, was published in Science Advances. Science.org has an article titled "Sci Adv. abj2946."
Science Advances has journal information.
The study found that the ocean started getting warmer decades earlier than we thought.
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