The surface of the Atlantic Ocean has seen its hottest temperatures in nearly 3,000 years within the past decade, a potential indicator of future ice melt near the North Pole, according to Massachusetts and Canadian climate scientists.
A team of researchers from the University of Massachusetts Amherst and the University of Québec-INRS were able to extend the record of known Atlantic sea-surface temperatures from about 100 years to 2,900 years, the longest record available, the researchers said in a statement.
“Our unique data set constitutes the first reconstruction of Atlantic sea surface temperatures spanning the last 3,000 years and this will allow climatologists to better understand the mechanisms behind long-term changes in the behavior of the Atlantic Ocean,” author Pierre Francus from the University of Québec-INRS said in a statement.
The group’s study was published Monday in the journal Proceedings of the National Academy of Sciences.
The team, also led by Francois Lapointe and Raymond Bradley from UMass Amherst, looked at “perfectly preserved” annual layers of sediment from the bottom of Sawtooth Lake in the Canadian High Arctic, according to a statement released by UMass Amherst.
By measuring the concentration of titanium in these layers — deposited in the lake sediment from centuries of rock-weathering — the scientists were able to estimate the relative temperature and atmospheric pressure over a period of time.
The scientists say cooler temperatures over the North Atlantic are associated with a relatively low atmospheric pressure pattern over much of the Canadian High Arctic and Greenland. That pattern also causes slower snow melt in the region and higher titanium levels in the sediments. The opposite is true when the temperature over the ocean is warmer — atmospheric pressure is higher, snow melt is rapid, and sediment titanium levels are lower.
This makes studying this lake a good indicator, Lapointe said in a telephone interview.
“Using these strong links, it was possible to reconstruct how Atlantic sea surface temperatures have varied over the past 2,900 years, making it the longest record that is currently available,” Lapointe said in a statement.
The study also found that the coldest temperatures were found to be between about 1400 to 1600 A.D.
Other data backs up what they found: The researchers said that independent sediment records from other places around the Atlantic, such as the north of Iceland and off the shore of Venezuela, significantly correlate with what they found, confirming its reliability.
Changes in sea surface temperatures are connected to “major climate upheavals” such as droughts in North America and the severity of hurricanes, the researchers said, and run in 60- to 80-year cycles.
“Climate warming in the Arctic is now twice or three times faster than the rest of the planet because of greenhouse gas emissions from burning fossil fuels," the statement said. "Warming can be amplified or dampened by natural climate variability, such as changes in the surface temperature of the North Atlantic, which appear to vary over cycles of about 60-80 years.”
Lapointe said it’s been common in recent summers for there to be higher atmospheric pressure in the Canadian Arctic, with clear skies. Temperatures have often reached 68 degrees for days or even weeks at a time, as in 2019.
The surface waters of the Atlantic have been consistently warm since 1995, Bradley said, and scientists don’t know if conditions will shift to be cooler any time soon, which would provide some sort of relief for the “accelerated Arctic warming.”
If that change doesn’t come soon, conditions that would promote the melting of ice caps and ice sheets could continue. Bradley pointed to Greenland’s ice sheet, which lost a record more than 500 billion tons of mass in 2019.