The coring device has to be lowered blindly through 100 meters of water—too deep for divers to navigate—and land vertically at the right speed, rather than bouncing off a rock or tipping over in the currents, in order to capture a good slice of the soft sediment below.
The sampling is part of Ostrom Climate Solutions’s effort to help fill in the giant scientific blanks about kelp, the group of large brown algae that make up the oceanic “forests” of Canada’s west coast.
That work is needed to back the global push to make the aquatic resource eligible for carbon credits—a sometimes-controversial scheme whereby people can earn credit for stopping carbon dioxide from reaching the atmosphere, and sell that credit on to companies aiming to counteract their own emissions.
CFN is keen on the idea: if seaweed qualifies for carbon credits, then they could earn hard cash for restoring or farming kelp.
Like Ostrom Climate Solutions, they too are in the midst of their initial research into just how much carbon is stored under seaweed—and how much credit someone would deserve for helping seaweed to do that job.
Cascadia Seaweed, a three-year-old endeavor that has kelp farms in Barkley Sound, on the west coast of Vancouver Island, is Oceans 2050’s sole representative on the west coast of North America.
In the future, Duarte envisions a world plastered with four million square kilometers of seaweed farms globally , creating a thriving ecosystem for fish and collectively earning farmers billions of carbon credits a year.
Some credits have, for example, perversely incentivized companies to raze one forest in order to plant another, or to avoid decarbonizing their own business.
COP26, the United Nations climate meeting in Glasgow, Scotland, this past November gave a huge boost to the voluntary carbon-credit market by adopting new rules allowing nations to partially meet their emissions targets by buying these offsets.
So far, Verra has certified more than 855 million carbon credits, almost entirely for land-based projects including avoided deforestation and reduced emissions from manufacturing—sectors that were better understood scientifically and had larger-scale projects already underway in the market’s early days.
That’s because companies are willing to pay more for carbon credits that have side benefits for local populations and ecosystems, and that come with publicity-friendly stories and photos that buyers can paste into their advertisements and annual reports.
In many countries, seaweed farming is an accessible occupation for women.
Admittedly, quite a lot of the uptake is only temporary: seaweeds don’t have roots to channel carbon underground; they often bloom and decline seasonally and can be wiped out by occasional storms or surges of predators like sea urchins; algae that are eaten by fish or decay release carbon back into the atmosphere; and bits that fall to the seafloor can be kicked up again by trawling.
In 2016, Duarte and colleague Dorte Krause-Jensen pulled together the available evidence and estimated that seaweeds worldwide sequester a nontrivial amount of carbon.
The same Ocean Panel report states that the global area covered by seaweed is holding relatively steady at about 3.5 million square kilometers of coast but instead with farming.
That’s still just a tiny sliver of less than one percent of global emissions, which are on the order of 50 billion tonnes of CO2 equivalents a year.
Plus, Duarte and others note, seaweed has a host of side benefits: it can improve water quality, promote biodiversity, and reduce local ocean acidity for shellfish farms by soaking up CO2.
So far, however, the profit margins on selling seaweed for sushi, seaweed snacks, and other products are too small to support the scale needed to help save the planet from global warming.
Around 2012, CFN made headlines by starting to sell carbon credits earned by avoiding deforestation and planting in the Great Bear Rainforest in their territory on the northern BC coast.
Despite the challenges of trying to core the seafloor 100 meters down in often-bad weather during a pandemic, they managed to get seven good samples from five sites around the northern tip of Vancouver Island and the mainland coast farther north.
As of the end of 2021, Oceans 2050 had full data for five farms. The results, Duarte says, roughly match his calculated estimate of three tonnes of CO2 being stored in sediments per hectare—but with a huge range, depending on everything from the type of seaweed to the local ocean currents and whether the seafloor is rocky or not.
Individual farmers could use default values for carbon credits based on models that are fed with data such as seaweed type and water depth, or they could do some of their own coring to prove their particular potential for carbon storage.
Extrapolating from Duarte’s rough figures, that means they could eventually earn on the order of 10,000 credits a year, with a value of about $100,000 at prices around $10 per credit.
That’s a whole other way that seaweeds might qualify for carbon credits—but, in this case, it would be the cattle farmers, not the seaweed producers, claiming those credits and getting that cash.
“I’m pretty sure our ancestors would have seen the value.” Each First Nation in their alliance, she notes, has their own plans for how they might incorporate kelp carbon credits into their coastal management, but all are excited about the opportunities for jobs, for expanding productive coastal ecosystems, and for a possible novel cash stream.
For now, though, the real excitement is happening in the labs, as Rindt and Duarte comb through the data they need to introduce seaweed into the carbon-credit market.