Kelp and seaweed are powerful plants in many ways—they can offer a home to millions of sea creatures, protect coastlines, and could one day be used as biofuel. They’ve even been shown to make cow farts less environmentally lethal.

In Island waters, kelp nurseries are replenishing lost forests and the seaweed aquaculture industry is starting to take off. But it’s the forests’ potential to absorb and trap carbon that’s making the biggest waves in climate research.

Now, local scientists are gathering the full picture of Canada’s sprawling kelp forests, which grow near the ocean’s surface and far below the waves. They’re also beginning to understand how much carbon these marine plants capture and whether Canada can count on them on the road to net-zero emissions.

In a study released this week, a team of researchers from 14 institutions—including UVic—used aerial and satellite maps of kelp forests on the water’s surface (like BC’s bull kelp) and below the surface. Through this, the team built a national kelp forest database to calculate the carbon that gets absorbed, stored, and exported deep in the ocean.

The study aims to address gaps in data that make it difficult to confirm the potential of a country’s kelp forests to sequester carbon. The study offers “a blueprint for Canada and other countries to follow when assessing their kelp forests," says Jennifer McHenry, lead investigator and post-doctoral student at UVic.

McHenry has worked with Blue Carbon Canada, a multi-institute research group that studies the ability of salt marshes, seagrass, and seabed sediments to act as natural climate solutions. These marine environments have been shown to sequester two to 10 times more carbon from the atmosphere than forests on land, but they’re also more vulnerable to degradation and need stronger protections.

“Our group has been trying to understand if kelp could be a part of that solution portfolio,” McHenry told Capital Daily. She says that, in addition to capturing carbon, these forests have other benefits as a food source and habitat for multiple species. 

“So, we really see this as a potential win-win solution as long as the numbers bear out.”

Until recently, there wasn’t enough data or tools available to calculate these benefits—this study is the first step in understanding all of Canada’s kelp potential.

“This particular study is really the first time that anyone's tried to estimate, at a national scale, how much carbon kelp forests in Canada might be capturing, and then how much of that might be stored long term in the ocean,” McHenry said.

The team’s research suggests Canada’s kelp forests could capture between 40,000 and 400,000 metric tonnes of carbon—which ends up stored in the deep ocean—per year. What the team is still unsure of is whether that carbon stays in the ocean floor—and out of the atmosphere—long-term. 

Further research is needed to understand whether Canada can rely on the carbon-capture value of these forests, but researchers with Blue Carbon Canada say these plants are worth protecting for other environmental benefits.

McHenry says the next steps in research should be to increase the kelp forest mapping and monitoring programs and gain a better understanding of where the captured carbon goes in the ecosystem. 

Preliminary data show that when kelp and other seaweeds are pulled to the deep ocean, they carry the trapped carbon with them. The plants eventually get buried under the seafloor, storing the carbon geologically. But understanding what this could mean Canada-wide will take more time.

Other climate scientists at UVic and beyond have urged governments not to rely too heavily on carbon accounting to alleviate climate change without ending fossil-fuel extraction. This is especially true for Canada, as devastating wildfire seasons lead to more extreme carbon emissions, making it imperative to cut down on human-caused emissions. McHenry echoes this point.

She says cutting out fossil fuels “must continue to be a top priority for Canada.” 

“Natural climate solutions really aren't a silver bullet, and they're certainly not an excuse to delay getting off fossil fuels,” McHenry urged. But she says that “every small contribution matters” when working toward net zero. Natural sinks are part of the toolkit for getting there. 

“The beauty of kelp is that you're not just protecting their [carbon-capture] functions. You're also protecting biodiversity, supporting fisheries, and supporting coastal communities that depend on that.

“I think there's a real synergy between protecting kelp for carbon purposes and for other purposes.”

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Correction: A previous version of this story claimed Blue Carbon Canada studied mangroves. While mangrove forests are an important marine carbon sink, they do not grow in Canada and aren't currently studied by BCC.