Seaweed’s significance was brought to my attention by two different climate-education programs at once: AirMiners Boot Up, a free, five-week course on carbon removal, and Terra.do’s Learning for Climate Action, a twelve-week class on all things climate change. As an ocean lover, advocate of nature-based climate solutions, and human invariably blown away by the awesomeness of our natural world, the fact that seaweed was a powerful tool for sustaining a happy and healthy planet immediately piqued my interest.
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💡 Check out AirMiner’s primer on Coastal Blue Carbon & Seaweed Cultivation – HERE – that got me started. It's an excellent selection of articles, podcasts and short videos – all accessible and totally interesting.
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The AirMiners and Terra intros were followed by my participation in a three week “climate-sprint” to explore means of scaling seaweed production for climate purposes. With a team of fellow oceans enthusiasts, I began interviewing macroalgae experts, reading everything I could find on the matter, and diving to the abyss of an aquatic rabbit hole.
Defining Seaweed
Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae, that grow in the ocean as well as in rivers, lakes, and other water bodies.The term includes some types of Rhodophyta (red), Phaeophyta (brown) and Chlorophyta (green) macroalgae.
Uses / Benefits / Cool Facts
Seaweed has myriad uses and benefits; here are some greatest hits. I’ll keep it short and offer links to resources that I’ve dug along the way.
- Food, Pharmaceuticals & More – While a novel cuisine in most places outside of Asia (where ~98% of seaweed is farmed), seaweed has been eaten by humans for thousands of years. It’s a nutritious and flavorful ingredient, whose use can be expected to grow to feed a rapidly growing global population. Moreover, seaweed extracts/polysaccharides – such as carrageenan, algin and agar – are in countless products, edible and not: from ice cream and shampoo to textile dyes and heartburn medicine.
- Bioremediation – Seaweeds absorb nitrogen (N) and phosphorus (P) during growth. N and P are also nutrients that, unfortunately, flood into riverways and coastal waters from agricultural and urban wastewater. Their excess spells disaster, stimulating cyanobacteria that chokes the oxygen out of the water. Seaweed cultivation can mitigate the problem by absorbing these discharged nutrients. In China, seaweed aquaculture annually removes ~75,000 tons of N and 9,500 tons of P.
- Carbon Sequestration – We must reduce our emission of greenhouse gasses AND pull CO2 out of the atmosphere. Seaweed, like all plants, sequesters C02 through photosynthesis. And it’s really good at it – drawing down more CO2 from the atmosphere by area than land-based rainforests do. According to the World Bank, farming seaweeds in less than 5% of U.S. waters could absorb 135 million tons of carbon.
- Ecosystem Restoration – The last century of overfishing, bottom trawling, polluting, and emitting greenhouse gasses has dealt serious damage to marine ecosystems. Rebuilding these ecosystems helps restore stressed species and food chains/food sources, clean up our waters, and stabilize environments that serve as natural erosion control.
- Methane Reduction – Methane is a brutal greenhouse gas with a warming potential more than 25 times that of carbon dioxide. Cows emit a crazy amount of methane, we’ve got a crazy amount of cows (~1.5 billion), and this livestock is responsible for approximately 4% of global greenhouse gas (which may not sound like much but is arguably a crazy amount). Turns out, adding small amounts of a specific seaweed – asparagopsis taxiformis – to cow feed reduces the animals methane output by upwards of 70%.
- Job Creation – New and growing industries create new workforce demands, and the wide range of applications for seaweed highlights impressive opportunities to scale. According to a World Bank study, farming seaweed in just .1% of the world’s ocean (about 100 million acres) could create 50 million jobs.
- Plastic/Materials Alternative – Seaweed extracts can be a key ingredient in bioplastics: sustainable and biodegradable alternatives to the synthetic, toxic plastic currently used for just about everything and polluting just about everywhere (~8 million tons of plastic end up in our oceans every year). Also, this Dupont cellophane ad from the 1950’s is terrifying: HERE
The list above covers the biggies but is non-exhaustive. Seaweed is being studied as a promising biofuel that’s less intensive to cultivate than terrestrial biomass. Seaweed has been shown to reduce the effects of local acidification in seawater. Seaweed may be a useful wave-damping tool for coastal protection in the face of rising sea levels and frequent storms/surges.
Seaweed is not a panacea but is versatile and undoubtedly compelling.
Note: As suggested above, certain seaweed uses/benefits are proven while others are still being determined. Considering the stakes – an increasingly unstable climate with communities and economies hamstrung by unsustainable practices – and the opportunity – a inhabitable climate with sustainable and prosperous communities and economies – I’ll argue that benefits/uses in nascent stages are worth attention, research and investment. Not hype.
