Canada's vast seabeds have emerged as a significant player in the battle against climate change, with new research revealing their potential to store billions of tonnes of carbon. As the nation with the seventh-largest exclusive economic zone (EEZ) globally, Canada could be central to efforts aimed at mitigating carbon emissions. Researchers estimate that the top one metre of seabed sediments alone hold around 2,300 billion tonnes of organic carbon. This figure is staggering when compared to the carbon stored in all coastal vegetation, being roughly 200 times greater.
The ocean's capacity to absorb carbon is diminishing due to climate change, amplifying the urgency of this discovery. Within Canada's EEZ, the upper 30 centimetres of sediment contain almost 11 billion tonnes of carbon. The study suggests that as Canada expands its marine conservation areas, it should prioritize protecting these carbon-rich seabeds, potentially as deep as 2,500 metres beneath the surface.
Researchers from the University of Victoria (UVic), Fisheries and Oceans Canada, and Oceans North collaborated on this study, emphasizing the often-overlooked value of muddy sea floors. They argue that traditional assumptions about oceanic carbon storage are significantly flawed. The ocean's biological pump plays a crucial role in cycling carbon dioxide deep into the world's oceans, storing it for up to thousands of years.
Approximately one-third of the sea-floor carbon originates from rivers that deposit organic matter into the ocean. This natural process highlights the seabed's potential to lock away up to 15 years' worth of global CO2 emissions. A recent feasibility study supports this claim.
The Solid Carbon project aims to leverage this potential by mechanically extracting carbon from the atmosphere and burying it in the seabed. Project proponents are currently seeking $60 million and regulatory approval for a large-scale demonstration in a protected marine area off Vancouver Island. The study identifies seabeds near New Brunswick, Nova Scotia, and Newfoundland and Labrador as prime candidates for protection.
Susanna Fuller, vice-president of conservation and projects at Oceans North, highlighted the importance of safeguarding these areas.
"Protecting important areas of seabed sediment will help to ensure that the carbon stays buried, rather than re-entering the carbon cycle and contributing to climate change," said Fuller.
Kate Moran, CEO of Ocean Networks Canada, acknowledged the challenges posed by human activities such as dredging.
"We are an imperfect species. We do things to keep populations safe. In some ways, dredging is important to prevent ships from going aground and spilling oil," said Moran.
Despite these challenges, Moran advocates for a careful assessment of such activities.
"But taking a precautionary approach, it would be useful to take a look at these activities and assess them for the risks and benefits — especially now that they’re identifying that we could be releasing carbon by some of these seafloor disturbances," she added.
Moran remains optimistic about the feasibility of seabed carbon storage.
“It’s feasible,” said Moran. “We’re putting it back where it belongs.”
Graham Epstein, a postdoctoral fellow at UVic’s department of biological sciences, warned about the potential consequences of disrupting these natural processes.
"It could slow the ocean’s abilities to continue to absorb carbon,” Epstein noted.
Epstein also highlighted the increasing popularity of "blue carbon" sinks among governments and businesses as a climate solution akin to forests.
"Blue carbon" sinks — including the world’s mangrove forests, salt marshes and sea grass beds — have become an increasingly popular climate solution for governments and businesses looking to pull carbon out of the atmosphere in the same way trees do," he explained.
With global average temperatures nearing and potentially exceeding 1.5 degrees Celsius above pre-industrial levels by 2024, the need for innovative climate solutions is pressing. Canada's seabeds could offer a crucial component in the broader strategy to combat climate change.
