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See inside a seaweed farm as it grow its carbon-sequestering crops

Seaweed serves as an excellent carbon sink, and so farming more of it to use in food could be an important step in the fight against climate change.

See inside a seaweed farm as it grow its carbon-sequestering crops
[Photo: GimMe]
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Off the southwest coast of South Korea, nets held together by buoys float in the ocean. But these nets aren’t there to catch any marine life, they’re instead scaffolding for seaweed, making up a seaweed farm for snack company gimMe Snacks.

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Unlike other vegetable farms, seaweed farms don’t need any additional water to grow, nor do they need soils or nutrients like nitrogen fertilizer. Instead, seaweed farms suck up nitrogen and phosphorus, along with carbon dioxide. The farms can be a powerful carbon sink: Seaweeds pull more CO2 out of the water than mangroves, salt marshes, and eelgrass combined.

[Photo: gimMe]
GimMe chose South Korea for its seaweed farm because of the silt and minerals in the water there that make for a nutrient-rich seaweed, the company’s cofounder Annie Chun says via email, and because the country already has seaweed farming and production infrastructure established. (South Korea is one of the world’s top seaweed producers).Chun was born and raised in Seoul, about an hour from South Korea’s west coast. “I wanted to do something to connect with my heritage,” she says.

[Photo: gimMe]
The gimMe farm grows a type of seaweed called Porphyra yezoensis, a red seaweed better known as nori. While some conventional seaweed farms use citric acid to prevent other species from growing on the seaweed, the company says, gimMe doesn’t. Instead, buoys that connect the nets rotate to periodically bring the seaweed out of the water and into the sun, which kills off the invaders.

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[Photo: GimMe]
In the water, there are no nets or barricades cutting off the farm from the rest of the ocean. “Nothing exists to prevent marine life from the farm—fish and shellfish are in the waters where we grow our seaweed,” says Chun. There’s no need, she adds, because the harvesting process poses no threat to marine life. While there may be an environmental impact related to shipping the seaweed snacks around the world or from its packaging (Chun says there are initiatives in the works that will “bring our sustainability to the next level”) as a whole, seaweed farms are a big environmental benefit.

The company works with several farms for its supply (the one pictured is about 3,000 square meters large), and while it hasn’t measured how much CO2 its farm has sequestered, J.D. Park, gimMe’s resident scientist in South Korea, says that 1 ton of seaweed can sequester about 1 to 4 tons of carbon dioxide per year. The company says it harvests 6,600 pounds of seaweed every three to four weeks from just this farm.

[Photo: gimMe]
Because it doesn’t need any fresh water, fertilizer, pesticides, or soil in order to grow, seaweed has been called a “zero-input” food. Seaweed farms can also improve water quality and even “buffer the effects of ocean acidification,” according to the National Oceanic and Atmospheric Administration (NOAA). And it’s getting more popular: since 1970, NASA says, farmed seaweed production has increased by about 8% per year. 

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Seaweed grows in the winter, its season beginning when water temperatures dip below 40 to 50 degrees Fahrenheit, and it’s harvested from the end of October to April. It grows quickly, too. On gimMe’s farm, the red seaweed grows 15 to 20 centimeters in three to four weeks, at which point it’s harvested by boat and taken to a facility to be rinsed, dried, and roasted into seaweed snacks and sushi nori.