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The changing sea

After an extensive multi-year study, researchers have some surprising insight into the critical role the Atlantic Ocean plays in regulating the Earth’s climate.

Dr. Brad deYyoung, professor, Department of Physics and Physical Oceanography, Faculty of Science, is the only Memorial scientist part of the international study that includes researchers from seven countries, including the United States, the United Kingdom, Germany, the Netherlands, France and China.

Their goal, happily successful, was to measure the deep circulation in the northern part of the Atlantic, from Newfoundland and Labrador to Greenland and from there to Europe.

“The ocean moves around most of the heat on the planet and this circulation is a key component of the global ocean climate transport system,” said Dr. deYoung, also a researcher with OFI and principal investigator on an OFI project focused on ocean data and technology and one focused on air-sea gas exchange in the Labrador Sea.

“The surprising result, shocking even, is that it turns out that the most of the transport is on the eastern side of the Atlantic. Very little total transport comes out of the Labrador Sea, much less than anyone expected. There is freshwater transported on our side, but not much deep circulation — the Meridional Overturning Circulation.”

Dr. deYoung says the research is important because the deep circulation of the ocean is a key regulator of the global climate system.

“There have been several predictions over the past couple of decades suggesting that this circulation is slowing down, because of human influences on the climate system,” he told the Gazette.

“If this circulation does slow, as is expected, it would have an enormous impact on both the climate and weather of our region.”

The new findings were recently published in Science.

Dr. deYoung was part of a team that included researchers from 16 global institutions. The group launched the research project, the Overturning in the Subpolar North Atlantic Program (OSNAP), in 2014.

N.L. fieldwork

Dr. deYoung was involved in the design and management of the project while leading studies off the province’s coast.

As an international project involving an enormous amount of field work, he says there was “a lot” of co-ordination required.

“Locally we contributed to the moorings here on the Newfoundland shelf, part of the whole observing array. We also deployed gliders along the arrays and in the Labrador Sea. Our interest was on the link between the deep winter convection in the Labrador Sea, which influences much of the oceanography in this region, and the deep circulation.”

‘Learn something new’

Armed with the new insight, the team of researchers will continue monitoring the deep ocean as well as try to figure out what is happening in the Labrador Sea during the winter when convection happens.

Dr. deYoung says there are links to the uptake of CO2 in the ocean basin and that it seems that the North Atlantic picks up more of the CO­2 from the atmosphere than do other parts of the ocean.

“We know that freshwater plays a key role in the oceanography of the Northwest Atlantic and now have new information about how freshwater transport influences the rest of the ocean,” he said.

“We have also seen other changes in our little corner of the ocean, declining nutrient supply and primary productivity. We would like to understand the links between all these changes. I would say that this proves something about the natural world that we keep having to relearn. New measurements always surprise us and lead to changes in our understanding.”