Could Seaweed Help Save Us From Climate Catastrophe?

“A couple of years ago, I would never have believed it,” one scientist said. “I’ve never seen anything like this.”
Seaweed can be used for biofuels, fertilizer, biodegradable packaging, pharmaceuticals and food -- “and the list goes on,” says University of California, San Diego, marine biology Professor Jennifer Smith.
Seaweed can be used for biofuels, fertilizer, biodegradable packaging, pharmaceuticals and food -- “and the list goes on,” says University of California, San Diego, marine biology Professor Jennifer Smith.

When Albert Straus started running the family dairy farm in the 1990s, he converted it to organic, turning it into the first certified organic dairy farm west of the Mississippi River. He aims for Straus Dairy Farm and Creamery in Marshall, California, to be carbon neutral by the end of next year. To limit the farm’s other greenhouse gas emissions, he uses an anaerobic digester to capture the methane from manure and convert it to energy. Next, he hopes to tackle another main source of methane: his cows’ burps.

“Cows are essential to reversing climate change,” Straus said.

The global livestock sector accounts for 14.5% of man-made greenhouse gases, more than all of the world’s automobiles, the United Nations has reported. Of that, nearly 40% is methane gas produced by digestion in cattle. The rumen, the first of four parts of a cow’s stomach, contains bacteria that ferment the high-fiber grass, hay and grains they eat. During this process, a combination of gases forms methane, which the animals emit mostly by burping and exhaling, but also in their flatulence and manure.

Perhaps the most promising solution for reducing bovines’ release of this powerful planet-warming gas? Feeding cows seaweed.

The red seaweed species formally known as Asparagopsis taxiformis is a “complete game changer,” according to Ermias Kebreab, associate dean for global engagement in the College of Agricultural and Environmental Sciences at the University of California, Davis. In July, preliminary results from the latest study that Kebreab co-authored on the algae found that it reduces intestinal methane production in beef steers by more than 80% when added to their feed. Other research found reductions of up to 98%, without adverse effects on the cows’ weight or the quality of beef produced.

“A couple of years ago, I would never have believed it,” said Kebreab, who serves as a scientific adviser for Blue Ocean Barns, which is commercializing a red algae feed supplement. “I’ve never seen anything like this.”

Seaweeds are being investigated for a number of climate-saving uses, from reducing methane emissions in livestock to replacing plastic in packaging.
Seaweeds are being investigated for a number of climate-saving uses, from reducing methane emissions in livestock to replacing plastic in packaging.
A. Martin UW Photography via Getty Images

Red seaweed’s powerful ability to slash methane emissions from cattle has garnered extensive attention, prompting scientists across the globe to work on ways to scale up its production.

Proponents of seaweeds have lots of other plans, too.

“They can be used for biofuels, and seaweed biomass can be used to make fertilizer to make crops on land more productive,” said Jennifer Smith, a University of California, San Diego, marine biology professor in the Scripps Institution of Oceanography who also advises Blue Ocean Barns. “Seaweeds can be used to make plastics that are biodegradable, and that are a lot less harmful than the plastics that we currently use that stick around on the planet for hundreds of thousands of years.”

Seaweeds produce compounds that have been investigated for use in antibiotics, cancer drugs and anti-inflammatories. Seaweed is a nutritious, sustainable vegetarian food (if more Westerners would come around to eating it). Growing it can even clean up polluted waters. “And the list goes on,” Smith said.

Seaweeds and seaweed-based products have the potential to usher in enormous environmental benefits. By removing carbon dioxide from the ocean, seaweeds decrease harmful ocean acidification resulting from man-made carbon emissions. In fact, the brown seaweed kelp is estimated to absorb five times more carbon than land-based plants. Seaweeds also remove excess phosphorus and nitrogen that collects in waterways as a result of fertilizer runoff, a condition called eutrophication that can cause toxic algal blooms and wildlife dead zones.

And unlike conventional agriculture, seaweed farming doesn’t require fresh water, fertilizer or external inputs, so there’s no need to clear land to cultivate it. The sustainability of seaweed is why researchers and entrepreneurs are investigating ways to scale up its production for a variety of goods — including food, fuel, pharmaceuticals and packaging — that can reduce greenhouse gas emissions and replace some of the plastic products that pollute oceans.

In Ermias Kebreab's research, red seaweed is pulverized, mixed with molasses and added to cattle feed to test how the supplement can reduce methane emissions from dairy cows.
In Ermias Kebreab's research, red seaweed is pulverized, mixed with molasses and added to cattle feed to test how the supplement can reduce methane emissions from dairy cows.
Gregory Urquiaga/UC Davis

Two years ago, Kebreab led the world’s first study to test red seaweed on live cattle. (Previous research on Asparagopsis mostly happened in lab settings or on other ruminant animals.) He hoped to help California dairy farmers lower the methane produced by their nearly 2 million cows, after lawmakers passed regulations in 2016 to reduce the state’s greenhouse gas emissions to 40% below 1990 levels by 2030.

“We are trying to find solutions, because farmers need to reduce emissions,” Kebreab said. “And we hope that in the next two or three years, we will have not just one but two or three different solutions that could be available to farmers.”

Blue Ocean Barns’ red seaweed supplement stops hydrogen from binding to carbon atoms during digestion, which produces methane. It makes up less than 0.3% of the cattle’s feed. With headquarters in Redwood City, California, and production operations mostly in Hawaii, the company plans to make the red seaweed it farms commercially available by the end of 2021, CEO Joan Salwen said.

“It’s now gotten past where a lot of additives have failed,” Salwen said. Some potential supplements worked in the lab, but not in the field. For instance, coriander and turmeric can reduce animal methane emissions, but it turns out cows don’t like curry spices. The microbes in animals’ stomachs adapted to other supplements, such as the antibiotic monensin, making them less effective. “The farmers who do know about what [Asparagopsis] can do are really excited.”

Albert Straus wants to prove the potential of red seaweed on his dairy farm.
Albert Straus wants to prove the potential of red seaweed on his dairy farm.
Straus Dairy Farm and Creamery

Straus recently received a U.S. Department of Agriculture National Organic Program waiver to use Blue Ocean’s additive for a six-week experiment on his farm. “My hope is to be the first commercial trial in the United States for this red seaweed,” Straus said. “We already add vitamins and minerals to the rations for the cows. This could be part of that expense. It shouldn’t be a financial burden on farms. I think it’s a minor change that can be really beneficial.”

He expects his seaweed trial to begin in the next few months.

Food and Drug Administration approval to use an Asparagopsis additive in livestock feed could take up to three years, Kebreab estimates. Since Australia and the European Union don’t face the same regulatory hurdles, he anticipates they will lead the way in bringing Asparagopsis to scale. Efforts are already underway.

In Australia, red seaweed technology developer CH4 Global is partnering with the Narungga Nation Aboriginal Corporation to commercially produce red seaweed, an undertaking designed to create employment, training and leadership opportunities for Indigenous peoples in the fight against climate change.

Australia’s national science research agency is working to mass-produce red seaweed via a startup called FutureFeed, and expects its products to be commercially available to the Australian beef industry in 2021 (and to the U.S. market in 2022).

An estimated 35,000 tons of dried seaweed must be produced to reach just 30% of the Australian market annually, which is why FutureFeed is working to develop a global seaweed supply chain, an effort that could boost economies worldwide.

Traditionally, people have hand-collected or foraged for naturally growing seaweed. This can be time-consuming and labor-intensive, but it remains a popular form of collection. Smith points out, however, that not only is this method of gathering seaweed not scalable, it can lead to overharvesting. “Most large-scale commercial production of seaweed takes place in Asia in ocean-based farms where seaweeds are ‘seeded’ onto suspended lines that are anchored to the bottom of the sea floor,” she said. It can also be cultivated on land, in tanks of seawater. This approach is especially useful for species that are sensitive to environmental fluctuations, or for those too delicate for open-ocean farms.

Eight Asian nations produce about 99% of the world’s seaweed, but Europe could ramp up local production of seaweed in its nutrient-dense waters — from 300,000 tons at present to 8 million tons in the next decade, according to a recent report from the Seaweed for Europe Coalition, which includes seaweed businesses, academics and scientists. By 2030, the seaweed sector in Europe could grow to a $9 billion industry and create 115,000 jobs, particularly in low-income coastal areas, according to the report.

“If aquaculture is developed the right way, it can be a huge win for conservation and a huge win for providing sustainable food for future generations.”

- Robert Jones, the Nature Conservancy

It identified seaweed-based animal feed, food for human consumption and biostimulants — biologically derived substances that boost crop productivity without causing the groundwater contamination and marine life destruction that chemical fertilizers doas the areas likely to see the most growth.

Maria Damanaki, Seaweed for Europe co-chair and former European commissioner for Maritime Affairs and Fisheries, calls the use of thin layers of seaweed in food packaging a particularly cutting-edge breakthrough. The Indonesian startup Evoware, founded in 2016, is a pioneer of this innovation. In 2017, it received the New Plastics Economy’s $1 million Circular Design Challenge award for replacing the conventional plastic packets and sachets that contain food products, like flavoring for instant noodles, with edible and dissolvable seaweed-based material.

Public awareness about seaweed’s sustainability may be growing, but getting more Westerners to eat the aquatic vegetables will require changing perceptions about them. Damanaki said that people question whether algae will taste good, even though seaweeds are staples of many Asian cuisines and have a wide range of health benefits.

“[Seaweeds] are one of the world’s biggest superfoods in terms of their ability to produce vitamins, minerals, protein and fiber,” Smith said. With respect to minerals like sodium, potassium and iron, “they’re 10 times more nutritious than any leafy green vegetable we can grow.”

Seaweed salad, seaweed soup and seaweed crisps are just some of the algae-based menu items found in restaurants and supermarkets across the world. The sea vegetables are also found in poke bowls and sushi. Many people reluctant to try seaweeds may already be eating them without knowing it, since food companies use seaweed as an additive, for example replacing animal-based products in gelatin.

In addition to the challenges of cultivating consumer confidence and building infrastructure and investment in a nascent industry, Damanaki worries that strict licensing requirements to farm seaweed will hold back development. “We want [politicians] to understand how it is different from the other aquaculture projects, which are sometimes very controversial because people think they’re a burden to the environment,” she said. “Seaweed production is restorative to the environment.”

That is, when it’s done right.

Seaweed aquaculture can improve human well-being and the health of oceans, said Robert Jones, the Nature Conservancy’s global lead for aquaculture, but he stressed how important it is that commercialization unfolds with care.

Invasive algae can overrun marine ecosystems.
Invasive algae can overrun marine ecosystems.
Algefoto via Getty Images

“If aquaculture is developed the right way, it can be a huge win for conservation and a huge win for providing sustainable food for future generations,” Jones said — particularly in how it can reduce the climate impact of meat production.

“If it’s not, we will continue to be plagued by some of the historical challenges associated with the aquaculture sector,” he added, including changes in the nutrient balance of water that can affect wild fish, disease spread in seaweed farms, and the proliferation of invasive species and habitat degradation. “The stakes are high.”

In countries such as Indonesia, China and the Philippines, the seaweed industry grew exponentially without many licensing or regulatory systems in place, according to Jones, who said that lack of oversight has sometimes resulted in natural seagrass beds being replaced by seaweed farms. Many of these concerns can be mitigated with guidelines that limit where seaweeds can be grown for commercial purposes (which needn’t add onerous regulatory burdens).

Aquaculture may be booming along Asian shores, but the U.S. is far from competitive in the industry, due in large part to complicated licensing processes. About a fifth of U.S. seafood production comes from aquafarms on the West, East and Gulf Coasts and Hawaii, which mostly produce shellfish and salmon. Off the Southern California coast, where the anti-methanogenic seaweed Asparagopsis grows, marine experts would like to see more commercial aquafarms open.

“Aquaculture should be given even more of a fair shake in California, because it’s an incredible coastal state,” said Peter Kareiva, president and CEO of the Aquarium of the Pacific in Long Beach, California. Given the state’s tight regulations, Kareiva thinks it could take years to launch and develop an aquaculture business there.

Humboldt State University in Arcata, California, is partnering on a pilot project to develop the state’s first commercial, open-water seaweed farm in Humboldt Bay. Called HSU-ProvidenSea, the half-acre farm is a collaboration between Rafael Cuevas Uribe, an associate professor in Humboldt State’s Department of Fisheries Biology, and Karen Gray, California reef manager at GreenWave, a nonprofit that specializes in regenerative aquaculture. The farm will grow Palmaria mollis, or dulse, a native red seaweed that is widely known for having a bacon flavor when fried and can be used in soups, breads, salads and other foods. Researchers have also studied its potential to fight obesity in animals.

Uribe and Gray planned to produce dulse to be used as a soil additive on a local farm, but they have received inquiries from people interested in buying the seaweed to develop new products ― for example, extracting a protein from the algae that could be incorporated into the Impossible Burger.

Getting the operation up and running has been difficult. “Existing policy and regulations in California make it challenging for a new small-scale farmer to start up operations and run a profitable business,” Gray and Uribe said in an email. “It’s a huge barrier to entry.” They noted that the regulatory process varies from state to state and is more straightforward on the East Coast and in Alaska.

Joan Salwen (left) and Smith look at seaweed specimens.
Joan Salwen (left) and Smith look at seaweed specimens.
Blue Ocean Barns

At its production facilities in Hawaii, Blue Ocean Barns cultivates seaweed in tanks on land. Although some argue that growing seaweed in the ocean works better and saves more money, land-based seaweed farms circumvent many of the problems that can occur in open waters.

“We’re producing seaweed in a way that scales up economically and protects ocean ecosystems while promoting really high-quality plants,” Salwen said. Growing seaweed in a carefully controlled environment can improve the algae’s growth rate and quality while minimizing threats — such as plastic pollution, mammal entanglement risks, and nutrient imbalances — to the marine habitat.

Some people are skeptical that enough seaweed can be produced to significantly reduce climate change. With roughly 1 billion cows in the world, Kareiva questions whether a sufficient amount of Asparagopsis can be cultivated to lower cattle methane emissions: “If we’re going to claim this is going to be world-changing as a supplement, and small-scale experiments show this is really a possibility, then what would the production need to be? Where are we going to get enough seaweed?”

Salwen said Blue Ocean’s land-based seaweed cultivation technology could feed nearly a million head of cattle in the United States. FutureFeed CEO Andrew Gatenby has said scaling up to commercial levels is the biggest challenge. The Australian startup is working with potential suppliers around the world, and Gatenby emphasized that Asparagopsis can be grown in tropical or temperate climates, as far north as San Francisco and the Mediterranean Sea.

Although commercialization of Asparagopsis and other seaweeds is still a work in progress, Jones expressed optimism about these aquatic plants. “What excites me is the potential to see seaweed aquaculture as a solution to many of the challenges affecting our ocean and the communities that rely upon it,” he said.

Not only does it offer alternatives to conventional methods of production that yield climate-damaging emissions, but it combats coastal pollution, supports fish, and creates jobs in coastal communities where there might be few options, he added. “There is so much to like about this.”

HuffPost’s “Work In Progress” series focuses on the impact of business on society and the environment, and is funded by Porticus. It is part of the “This New World” series. All content is editorially independent, with no influence or input from Porticus. If you have an idea or tip for the editorial series, send an email to

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