Scientists call on Canada to study North Atlantic’s role in global climate

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Marine scientists in Canada are calling for a new initiative to study one of the most significant and least-observed elements in the global climate system – the North Atlantic Ocean.

If realized, the effort would bring together international partners to monitor the region, which, because of its unique characteristics, is one of the key areas where carbon is transferred from the atmosphere into the deep ocean.

Those advocating for the project – dubbed the North Atlantic Carbon Observatory – say Canada is well positioned to play a leadership role, and that without the data the project would gather, it will be impossible to know if international commitments to limit global warming can succeed.

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“We are one of the few countries for whom the critical parts of the carbon sink are literally in our backyard, within arm’s reach of our ships, so we can conduct this effort in a way that nobody else can,” said Anya Waite, scientific director and chief executive officer of the Ocean Frontier Institute, a federally funded research hub based in Halifax.

Dr. Waite, who presented the concept on Wednesday during a session at the United Nations climate conference in Glasgow, Scotland, said it would bring together separate efforts that are now under way around the globe and point the way toward a more sustained, long-term, ocean-observing program that supports international climate goals.

Since the beginning of the Industrial Revolution, the world’s oceans are estimated to have taken up more than 30 per cent of all the carbon that humans have released into the atmosphere. On its own, the North Atlantic has absorbed about one-third of that, making it one the most intense carbon sinks on the planet on a per-square-kilometre basis.

A big reason for this is called the Atlantic meridional overturning circulation – a pattern of ocean currents that brings warmer and saltier surface waters from the tropics to the North, where they sink down and help carry carbon dioxide absorbed by the water into the deep ocean.

A prime motivation for better understanding this process is that any significant shift in ocean circulation would affect the amount by which countries need to reduce their carbon emissions to meet the goal of net zero.

“The variability of the ocean carbon sink is a critical unknown,” Dr. Waite said. “If we don’t take it into account, we’ve got a changing baseline ... and it’s absolutely impossible to have a credible carbon dioxide reduction scheme.”

Climate scientists point to several unknowns that make it difficult to predict how steeply global warming will trend upward this century, the biggest being how individuals, companies and governments will choose to act on the problem. There are also questions about how carbon uptake is changing in the terrestrial environment because of land use, deforestation, wild fires and other effects.

From that perspective, the ocean is not quite as unpredictable, however, it remains extremely important, said Neil Swart, a research scientist at the Canadian Centre for Climate Modeling and Analysis in Victoria, who is not involved in the proposal.

Dr. Swart said that the North Atlantic is an ideal place to study the ocean’s role in the global carbon cycle because any uncertainties in the system that can affect the accuracy of climate models are magnified there.

“Having sustained, long-term, high-quality observations would really help us quantify those [uncertainties] and validate the models,” he said.

Brad deYoung, an oceanographer at Memorial University in Newfoundland and a supporter of the proposal, said that one of its key goals was to provide a reliable stream of data over many years, much like weather stations do on land, instead of relying on short-term observations by individual research teams with limited funding.

Such data would help scientists better interpret recent evidence that points to changes in the circulation system in the North Atlantic. This may have to do with the increase in freshwater flooding onto the surface waters, particularly in the Labrador Sea, because of the melting and break up of Arctic ice.

Dr. deYoung said that the effort requires probes that can automatically gather data without humans present, particularly during winter months, which are important from a scientific perspective but are notoriously challenging for ship-based measurements because of cold temperatures, extreme winds and treacherous seas.

“Nobody wants to be out there in a boat, but surface vehicles and autonomous underwater vehicles like gliders can carry sensors out there and can operate even in winter conditions,” he said.

Canada has already been moving in the direction of more autonomous data gathering in the ocean. Last year, a $9-million grant from the Canada Foundation for Innovation was awarded to Dalhousie University in Halifax for 40 autonomous probes, known as “Argo floats” that can periodically alter their buoyancy to dive deeply below the surface to make measurements and then come up again to transmit data.

Katja Fennel, an oceanographer who studies the effects of climate change on marine systems and is principal investigator for the project, said the effort would be a partial step toward the much larger vision of the North Atlantic Carbon Observatory.

“I’m a bit optimistic, at least about our ability to now finally observe what is happening in the ocean,” she said. “In order to take action, we have to know what’s happening ... and now there is a viable path to get that knowledge.”

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