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Lying in plain sight and lapping against our shores is what scientists describe as an unsung hero that has been quietly absorbing heat and keeping the world's temperatures under control. And over the coming days, a group of Canadian researchers hopes to persuade the world that the ocean has a crucial role to play in fighting climate change. 

Prof. Anya Waite is leading a delegation from Dalhousie University's Ocean Frontier Institute to attend the 27th annual Conference of the Parties of the U.N. Framework Convention on Climate Change — better known as COP27 — in Sharm el-Sheikh, Egypt, starting Sunday. They plan to share ways the deep blue carbon sink acts as a buffer and impacts climate forecasts.

Waite said most people know that rainforests are the lungs of the planet, keeping temperatures down and filtering the air. 

"But oceans hold more carbon than all the rainforests on Earth," she said in an interview. "And deep blue carbon is carbon that's held by the deep blue sea. So the open ocean, the high seas, which go down to 4000 meters in depth … they hold most of the carbon on Earth. And that's something people really aren't aware of."

Scientists must understand the role oceans have played to date in mitigating climate change, she said, noting it's also important for coastal communities to know how they must adapt to shifting conditions. 

Oceans have absorbed 90 per cent of the earth's heat emissions so far, Waite said. She credits oceans for the fact the world has not yet blown through the goals set out in the Paris Agreement, the international climate pact that pledged to limit warming to below two degrees Celsius and curb it to 1.5 if possible.

But there is a danger that these carbon sinks will turn to emitters as the waters warm, melting caps of frozen methane and other greenhouse gases that lie scattered on the sea floor, she said.

"The capacity of the ocean to absorb carbon is gently declining," Waite said. "But then on top of that we're seeing that there's these … extreme events or rare events that can potentially release carbon in short notice. And we don't really understand those."

Scientists and communities are beginning to understand the importance of common shoreline features such as marshes, kelp forests and sea grass meadows that keep blue carbon rooted in the soil, she said.

Waite said such "blue carbon ecosystems" help retain emissions, in addition to enhancing biodiversity. But it is further offshore that the biggest carbon stores are to be found, she said.

Changes in ocean temperatures also change water currents, she noted, adding melting glaciers from the Arctic put fresh water into the ocean and force marine animals to either relocate or adapt to their changed environments. 

The endangered North Atlantic right whale, for instance, has moved from the Gulf of Maine it used to call home into the Gulf of St. Lawrence.

"There's a whole lot more shipping in the St. Lawrence, and those animals are now coming in contact with ships way more often, bringing an already endangered species to the brink of collapse," Waite said.

Shifts in ocean circulation and temperatures also change animal behaviour, sometimes causing them to move in search of more comfortable environs that ultimately put them at greater risk.

Canada is uniquely positioned to tap into the ocean's potential benefits, Waite said, noting the country is surrounded by wide open spaces of water on three sides. But though Canada has the luxury of using the deep blue to balance its carbon output, she said the issue has received limited attention and financial resources so far.

"Climate change is essentially a multi-billion dollar problem. And yet to observe and care for the oceans costs, way less than that," she said. "So a small investment can bring an enormous benefit for humankind. The problem we have is that the ocean is sort of out of sight, out of mind."

This report by The Canadian Press was first published Nov. 6, 2022.

Hina Alam, The Canadian Press