Projects to study Labrador Sea's role in Earth's climate system

Sep 23rd, 2014

Kelly Foss

Projects to study Labrador Sea's role in Earth's climate system

Memorial University is at the centre of two international, multi-million dollar projects to get a better understanding of the role of the Labrador Sea in the Earth’s climate system.

The Ventilation, Interactions and Transports Across the Labrador Sea, or VITALs, is a pan-Canadian initiative, which includes scientists from 11 Canadian universities, multiple federal government laboratories, and industrial and foreign partners.

The research network is attempting to understand and model the functioning and vulnerability of the Labrador Sea including its uptake of oxygen, carbon and heat exchange with the atmosphere. These interactions are poorly understood and actively evolving under changing climate conditions. Researchers believe new observations and modeling will help determine what controls these exchanges and how they interact with varying climate, providing better information for future climate prediction.

“The Labrador Sea is one of the three areas on the planet where deep water forms,” explains Dr. de Young. “Which means it’s where the deep ocean breathes the atmosphere. We want to measure how that happens and what the scale of it is.”

Memorial’s role is focused on the deployment of instruments and numerical modeling. This summer, Dr. de Young lead a team, including Dr. Ralf Bachmayer (Engineering and Applied Science) and Dr. Evan Edinger (Department of Geography), to the region to deploy moorings along the shelf and into the deep ocean. These moorings and mobile platforms will remain in place and collect data over a period of at least four years. They also flew ocean gliders across the shelf break, collecting real-time data, which will help other teams, including Dr. Entcho Demirov, also of the Department of Physics and Physical Oceanography, during the numerical modeling phase.

Dr. de Young is also the only Memorial researcher involved in the international Overturning in the Subpolar North Atlantic Program, or OSNAP, which is also partly occurring in the Labrador Sea.

This program is designed to provide a continuous record of the full-water column circulation, which sees surface currents taking warm water in one direction while the deeper colder water circulates in another. Understanding these currents and their impacts on weather and climate in the North Atlantic will begin this summer with the deployment of array of sensors and floats which will collect data over the next several years.

“This project is looking at deep circulation in the North Atlantic. There is a circulation called the meridional overturning circulation, which is the large-scale climate driven circulation that has a hundred year timescale,” said Dr. de Young. “We want to measure the variability of this circulation over the years and decades to see if climate related influences can be measured from that circulation.”

Dr. de Young says the two projects are complimentary. While one looks at the very large scale circulation character of the North Atlantic, the other focuses on what happens in this particularly intense region of convection - convection being where the water cools at the surface to such an extent that it sinks down to the near bottom part of the ocean.

“It doesn't reach the very bottom in the Labrador Sea,” he explained. “There's nowhere in the North Atlantic where water reaches the bottom. Bottom water is formed in the Antarctic. That then percolates through the global ocean.

“The ocean is not like a lake where typically everything turns over. Because it is so much deeper, many kilometers deep, and stratified with temperature and salt, the ocean is more complicated. The overturning only happens in particular places: Greenland, Antarctica and the Labrador Sea. That’s why we are doing research there, because it’s relatively unique.”

He says that makes the Labrador Sea a logical place to try and understand what regulates CO2 exchange between the ocean and the atmosphere in one of the places where it’s most dynamic.

“Clearly CO2 is tied to the whole climate change question, because carbon dioxide levels continue to rise in the atmosphere, and over the last 100 years the ocean has taken up a fair bit of the CO2,” said Dr. de Young. “About a third of the C02 that's emitted anthropogenically goes into the ocean.

“There's evidence now the uptake by the ocean is slowing down. The ocean can't continue to take up C02 at the same rate. The question will logically be what happens to global climate change warming if the atmospheric concentrations increase more quickly because the uptake by the ocean slows down? And that's the expectation. The rate of increase of C02  in the atmosphere does seem to be speeding up, but we cannot say why for sure.  So far we don't understand enough to say why with any confidence. ”

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