Peace Magazine: Eating Seaweed

Peace Magazine

Eating Seaweed

• published Jul 06, 2024 • last edit Jul 11, 2024

Hey, Mom! There are two billion people coming for dinner! I’ll go get some seaweed!

Yes, there are expected to be two billion additional human beings by 2050, and all of us will want to eat. But, as we now realize, the production of food is affected by global warming. Extreme weather events are becoming more common, and this will reduce crop yields and the availability of food globally. What else can be produced to solve the expected shortfall?

Seaweed. At present, seaweed provides only a small fraction of the world’s food supply – primarily in Asian diets. But there are experimental projects to farm seaweed on a much greater scale.

Over the past fifty years, large areas of the ocean have become “deserts” for various reasons. Some zones do not receive enough oxygen, some are polluted by fertilizer run-off, and some zones lack sufficient nutrients to sustain animals or plants. The nutrients do exist in deeper areas but because the upper layers of the ocean are becoming warmer, it is harder to bring them up. To sustain organisms in the zone, some artificial “upwelling” device is required.

These experimental projects involve the construction of large floating grid platforms on which seaweed can grow, as well as pumps to bring up nutrient-rich deep water for the seaweed and the growing stocks of fish. The seaweed and fish will then provide many of the nine billion humans with a nutritionally rich diet. Many types of seaweed are highly nutritious, containing vitamins (like vitamin K, B vitamins, and vitamin C), minerals (including iodine, calcium, and iron), proteins, and antioxidants. They offer health benefits such as improved digestion, thyroid, brain and nervous system support, and anti-inflammatory properties, making them beneficial in a balanced diet.

There is also another advantage to this plan: Seaweed has the potential to be a carbon-negative resource, removing carbon from the atmosphere and sequestering it in the ocean depths. By photosynthesis, seaweed absorbs carbon dioxide from the air and converts it into biomass, so it is a carbon negative crop. It grows fast; giant kelp can grow 50 cm a day and reach 60 meters in length. Up to 25 percent of the seaweed will fall off the floating platform and sink, sequestering carbon in the depths of the ocean. If these experiments fulfill expectations, they will show how seaweed farming can contribute to carbon sequestration efforts, making it a valuable tool in combating climate change.

Seaweed farming is already growing anyway. Alaska, Maine, France, and Norway have each more than doubled their seaweed production since 2018.
Today an estimated 95 percent of the world production is farmed rather than gathered from wild seaweed forests. As of 2022 the main producers were China (59%) and Indonesia (29%); followed by South Korea (5%).World production in 2019 was over 35 million tonnes, representing about one-third of all marine aquaculture.


To anticipate the future of this trend, Project Save the World brought three seaweed researchers together to discuss the pluses and minuses of promoting seaweed worldwide as a food staple. In early May, we held a Zoom forum with the experts from three continents.

Dr. Flower Msuya is a senior researcher at the Zanzibar Seaweed Cluster Initiative. She works with seaweed farmers to help them bring innovations into the industry. She is proud of having introduced the habit of eating seaweed in Tanzania and has published a number of journal articles and books.

Professor Ole Mouritsen is a professor emeritus of gastro physics and food innovation at the University of Copenhagen in Denmark. He studies its chemical and physical properties – even the factors determining whether or not a recipe will produce a tasty dish.

In Australia, Dr. Paul Cornell is a senior lecturer at the Royal Melbourne Institute of Technology. His research aims to support government and non-government organizations to manage and rehabilitate marine, coastal and freshwater ecosystems.

Dr. Msuya develops technologies that help Tanzanian farmers produce more seaweed and higher-value species of seaweed, and to help develop the industry there connect it to the world market.

She reports that the most lucrative crops are not growing very well because of climate change. Unfortunately, Tanzania does not have many direct links to the markets, as do countries like the Philippines, and Indonesia, whose farmers can work closely with processing plants.

Tanzanian red seaweed is sometimes exported to companies in Europe that extract carrageenan, a valuable product that is widely used as a thickener, stabilizer, and gelling agent in ice cream, sauces, and desserts. It improves texture and solubility in foods without altering flavor, and is also used in some manufacturing other products, including pharmaceuticals, cosmetics, and cloth. However, almost all the profits go to the European companies that extract the carrageenan, not to the Tanzanian farmers, who use the seaweed to make lotion, hair oil, food and other products that they can use directly at home or sell in nearby markets.

Flower Msuya said that she is encouraging the farmers to farm in deeper waters because climate change is bringing about a lot of diseases and pests in the shallow waters. The price has actually doubled for one type of seaweed, but it is too sensitive to heat to grow there. Farms in deeper waters produce the higher value seaweed. However, Tanzania is in the Indian Ocean, where large waves mix the water and create a fortunate natural upwelling of nutrients, but where it is riskier to farm in deeper waters because of the roughness of the waves.


Noting that few people in their countries are accustomed to eating seaweed, the experts talked about how to get anyone to like any new food. Flower Msuya recalls a time when she first started promoting seaweed. A man replied to her, “Young lady, why would I eat seaweed when there is food available?”

Ole Mouritsen has been working for years in Danish kitchens, studying the sensory perception of taste. But he also goes into the community, working with children and young people to teach them the value of seaweeds and how to cook them. People often ask Mouritsen what seaweed tastes like. He replies, “What do plants taste like?” Carrots and tomatoes taste different, and so do the 1,000 kinds of seaweed. He advocates incorporating seaweed into everyday dishes subtly, suggesting it can be used as a spice or added to familiar dishes to gradually introduce it into diets.

But Mouritsen says that in his universe, the most critical taste is umami, which is called the “fifth basic taste” alongside sweet, sour, bitter, and salty. It is often described as a savory or meaty flavor. This taste is imparted by glutamate, an amino acid, and is found in foods like meat, cheese, and certain vegetables including mushrooms and ripe tomatoes. Mouritsen says that it was discovered in an extract from kombu, the kelp that is the main ingredient of Dashi, the Japanese soup. He advises cooking seaweed as a vegetable. Fortunately, it does not need to be fresh. Drying seaweed decreases its weight by 80 percent and when it is soaked in water, it will taste and look exactly as it did originally. So, it’s best to buy dried seaweed, which can be stored safely for ten years.

Paul Carnell works to preserve ecosystems, particularly in the coastal areas. He worries that if it becomes a popular food, wild seaweed may be over-harvested. He said, “It’s difficult to buy Australian seaweeds here. We do have the wakame species that grows in the wild, but that’s been introduced, so it’s actually a bit of a pest down here in Australia. In some cases, people are saying, ‘Well, maybe we should be trying to harvest it. That’s one way to get rid of it!”

Finally, the experts expect to see seaweed used to reduce the global warming effect of cows’ burps. A species called asparagopsis can reduce enteric methane emissions by 90 percent. Carnell says that the evidence suggests that as an industry, it has “borderline” profitability.

You can watch the forum here: Then you are welcome to discuss the topic here:

Published in Peace Magazine Vol.40, No.3 Jul-Sep 2024
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