Catch and grow: A containment barrier to keep sargassum away from a beach. The idea is to cultivate the seaweed and extract useful materials to create products such as bioplastics and biofuel. — AFP
THERE’S a sea monster lurking in the Atlantic Ocean that could help save the planet.
Weighing about 4.5 million kg, this golden-brown creature is harmless enough floating in the sea – but if it lands on a beach, you’re in serious trouble.
Washing up as a thick, tangled mass of tentacles, it smothers delicate coral reefs and precious mangroves.
When it starts to rot, it scares away tourists, not only blocking access to pristine sandy beaches, but releasing a toxic gas called hydrogen sulfide, with an ungodly stench of rotten eggs.
The gas is irritating and can cause breathing problems.
The name of this monstrosity? The Great Atlantic Sargassum Belt. This 8,000km stretch of floating seaweed patches is getting a little out of control, to say the least.
Sargassum seaweed has existed for millennia in the Sargasso Sea, providing a habitat to ocean dwellers including tiny crabs and the grumpy-looking sargassum fish.
There, it’s such an integral part of the sea’s rich biodiversity that it’s sometimes referred to as the “golden floating rainforest.” But in the past decade or so, it has bloomed in terrifying proportions, becoming more of a threat than an oasis for coastal ecosystems and business owners alike in Florida and the Caribbean.
Hotel owners have seen drops in occupancy rates during beaching events, and fishermen are struggling both with the seaweed’s effect on local fish populations and on their equipment.
These huge blooms are likely an issue of our own making, as altered sea conditions caused by fertiliser runoff and environmental changes have allowed sargassum to metastasise. But some are seeing potential in the problem.
There is a lot of research and interest into seaweed cultivation as a carbon dioxide removal (CDR) method at the moment, but UK-based seaweed startup Seafields was attracted specifically to sargassum for a couple of reasons: Even though research shows its carbon uptake isn’t as high as other seaweed species, it grows rapidly, and it doesn’t need a surface to grow on.
Seafields’s ultimate ambition is to remove as much as one gigaton (Gt) of carbon dioxide annually – 40Gt of CO2 was emitted globally in 2022 – with 94,000 sq km of modular farms roughly the size of Portugal in the middle of the South Atlantic gyre, a large system of circulating ocean currents.
The idea is to cultivate sargassum and extract useful materials to create products such as bioplastics and biofuel or compress the seaweed into bales that will be sunk to the bottom of the ocean, storing the CO2 captured by the plants.
Achieving that vision will be years in the making.
In the meantime, Seafields wants to set up so-called “catch-and-grow” farms later this year to stop the sargassum from beaching in the first place.
The business will ultimately be funded by selling both sargassum-derived materials and carbon-removal credits for the sunken bales. But one challenge, along with the initial fundraising, is that the carbon-credit market as it exists today is too cheap and not trustworthy enough, as more carbon offsets prove to be little more than bunk. “It’s unfeasible to think that you can permanently remove a tonne of CO2 for US$5 (RM22), it needs to be closer to the International Monetary Fund’s US$75 (RM330.71)-per-tonne target,” John Auckland, co-founder and chief executive officer of Seafields, told me.CDR markets will need independent measurement, reporting and validation of each method as well as a robust understanding of the environmental impacts – something that’s particularly important when dealing with delicate natural ecosystems, which may not always act as expected.
Indeed, studies of both kelp and sargassum have suggested that their carbon-removal efficacy may be reduced once the whole ecosystem and feedback mechanisms are taken into account.
That’s why some scientists are concerned about the sudden influx of interest in seaweed-based CDR.
“Several companies are running before we can walk,” Ana Queiros, a senior marine and climate change ecologist at Plymouth Marine Laboratory, told me.
Queiros is part of a team finalising a review into the carbon benefits of seaweed farming and her conclusion is that, while seaweed does have great carbon uptake potential, aspects such as farm location, species and ecosystem-wide effects still need to be better understood before we can confidently claim any climate-mitigating effects.
For Seafields to be viable, it’ll have to ensure scientific rigour throughout the whole process.
That includes closely monitoring the potential impacts of large-scale farming on the high seas and dropping bales on the ocean floor.
Though the South Atlantic gyre is sometimes referred to as an oceanic desert due to low concentrations of phytoplankton, it’s still home to iconic migratory species including manta rays and baleen whales. The impression I got from talking to Auckland was that the company takes this seriously, aiming to become ocean “custodians.”
The company is working with an independent research firm INES, which specializes in studying the biodiversity and ecology of marine environments, and the National Oceanography Centre to provide an expansive environmental impact assessment.
Nature-based CDR methods can be controversial, but it’s important to recognise that we are living in the Anthropocene, and humans have been shaping the planet –intentionally or not – for centuries: the Great Atlantic Sargassum Belt and those huge garbage patches amassing in our ocean gyres are evidence of that.
With microplastics being found in deep-sea organisms, it seems that few places on the planet remain completely untouched by human activity these days.
The Intergovernmental Panel on Climate Change has acknowledged that CDR will play an important role in mitigating the climate crisis.
Therefore, we will need to harness our human power to influence the planet in order to start reversing the damage we’ve caused. Projects like Seafields can be part of that. We just need to ensure we take the time to invest in them responsibly. — Bloomberg
Lara Williams is a Bloomberg Opinion columnist covering climate change. The views expressed here are the writer’s own.
