Calgary Herald

Atlantic current heating Arctic

Waters warmest in 2,000 years, say scientists

- MARGARET MUNRO

Anew study has found that water flowing from the Atlantic Ocean into the Arctic is warmer than it’s been in 2,000 years.

The increased heat input has “farreachin­g consequenc­es” and is likely helping fuel the remarkable change underway at the top of the planet, European-U.S. scientists report in the journal Science on Friday.

“We find that early–21st-century temperatur­es of Atlantic water entering the Arctic Ocean are unpreceden­ted over the past 2,000 years,” say the scientists. They studied the Fram Strait branch of the North Atlantic Current, the major ocean conveyor that carries heat north from the tropics.

It cuts between Greenland and Norway and is “by far the biggest input into the Arctic,” says team leader Robert Spielhagen, of Germany’s Academy of Sciences, Humanities, and Literature.

The water flows counterclo­ckwise around the Arctic Ocean and he says it is sure to be contributi­ng to the Arctic meltdown that has seen record ice retreat and warming in recent years.

Annual average air temperatur­es have climbed almost three degrees Celsius at the Eureka weather station in the Canada’s High Arctic since 1972, a trend seen across much of the North, which is breaking records again this winter. In December sea ice extent was the lowest on record since 1979, and temperatur­es were above average in much of the Arctic.

To understand what is happening scientists say they need a better read on the long-term natural variation in the currents flowing north.

Few records go back more than 150 years, so Spielhagen’s team pulled up sediments up from the sea floor, which contain the remains of organisms that have been living and dying in the water over the eons. By studying the tiny-shelled organisms called foraminife­ra, which grow best under specific conditions, they could chart temperatur­es going back 2,000 years. Their sampling site was 1,500 metres below the water surface and under the path of Atlantic water flowing to the Arctic Ocean.

They report the water has warmed about 2 C since late 1800s. The top couple of centimetre­s of sediment, representi­ng the last 10 to 20 years, correspond­s with a summer temperatur­e of 6 C, which matches what is now seen in the northbound current.

The scientists say the data indicates that the modern warming is not just the latest natural variation or swing.

 ?? Courtesy, Nicolas van Nieuwenhov­e ?? A research vessel cruises through melting sea ice northwest of Norway, where deep ocean currents are carrying warm water into the Arctic.
Courtesy, Nicolas van Nieuwenhov­e A research vessel cruises through melting sea ice northwest of Norway, where deep ocean currents are carrying warm water into the Arctic.

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