The Coming Green Wave: Ocean Farming to Fight Climate Change

Seaweed farms have the capacity to grow huge amounts of nutrient-rich food, and oysters can act as an efficient carbon and nitrogen sink


For decades environmentalists have fought to save our oceans from the perils of overfishing, climate change, and pollution. All noble efforts -- but what if environmentalists have it backwards? What if the question is not how to save the oceans, but how the oceans can save us?

That is what a growing network of scientists, ocean farmers, and environmentalists around the world is trying to figure out. With nearly 90 percent of large fish stocks threatened by over-fishing and 3.5 billion people dependent on the seas as their primary food source, these ocean farming advocates have concluded that aquaculture is here to stay.

But rather than monolithic factory fish farms, they see the oceans as the home of small-scale farms where complementary species are cultivated to provide food and fuel -- and to clean up the environment and fight climate change. Governed by an ethic of sustainability, they are re-imagining our oceans with the hope of saving us from the grip of the ever-escalating climate, energy, and food crises.

The Death and Rebirth of the Ocean Farm

Ocean farming is not a modern innovation. For thousands of years cultures as diverse as the ancient Egyptians, Romans, Aztecs, and Chinese have farmed finfish, shellfish, and aquatic plants. Atlantic salmon have been farmed in Scotland since the early 1600s; seaweed was a staple food for American settlers.

Unfortunately, what was once a sustainable fishery has been modernized into large-scale industrial-style farming. Modeled on land-based factory livestock farms, aquaculture operations are infamous for their low-quality, tasteless fish pumped full of antibiotics and polluting local waterways. According to a recent New York Times editorial, aquaculture "has repeated too many of the mistakes of industrial farming -- including the shrinking of genetic diversity, a disregard for conservation, and the global spread of intensive farming methods before their consequences are completely understood."

Unsurprisingly, once information got out among the general public, "aquaculture" quickly became a dirty word. Industry responded with a strategy of mislabeling seafood and upping their marketing budgets, rather than investing in more sustainable and environmentally benign farming techniques.

But a small group of ocean farmers and scientists decided to chart a different course. Rather than relying on mono-aquaculture operations, these new ocean farms are pioneering muti-tropic and sea-vegetable aquaculture, whereby ocean farmers grow abundant, high-quality seafood while improving, rather than damaging, the environment.

One example is Ocean Approved in Maine, which cultivates seaweed that doubles as a nutrient-rich food source and a sponge for organic pollutants. Farmers in Long Island Sound are exploring diversifying small-scale organic shellfish farms with various species of seaweed to filter out the pollutants, mitigate oxygen depletion, and develop a sustainable source for fertilizer and fish meal. In southern Spain Veta La Palma designed its farm to restore wetlands, and in the process created the largest bird sanctuary in Spain, with over 220 species of birds.

Seaweed farms alone have the capacity to grow massive amounts of nutrient-rich food. Professor Ronald Osinga at Wageningen University in the Netherlands has calculated that a global network of "sea-vegetable" farms totaling 180,000 square kilometers -- roughly the size of Washington state -- could provide enough protein for the entire world population.

The goal, according to chef Dan Barber -- named one of the world's most influential people by Time and a hero of the organic food movement -- is to create a world where "farms restore instead of deplete" and allow "every community to feed itself."

But here is the real kicker: Because they require no fresh water, no deforestation, and no fertilizer -- all significant downsides to land-based farming -- these ocean farms promise to be more sustainable than even the most environmentally-sensitive traditional farms.

Ramping up food production without increasing greenhouse gas emissions is vital if we are to survive the coming decades. But land-based food production is entering an era of crisis. The U.N. estimates that global grain production will plummet by 63 million metric tons this year alone mainly because of weather-related calamities like the Russian heat wave and the floods in Pakistan.

Bun Lai, world-renowned sustainable seafood chef, believes that:

If done right, this new generation of green aquaculture is poised to become the most sustainable form of farming on the planet. We need healthy food that protects rather than harms our climate and Earth. It is a key piece of the puzzle for building a sustainable future.

Nature's Climate Warriors: Seaweed and Shellfish

Rather than finfish, the anchor crops of the emerging green ocean farms are seaweed and shellfish -- two gifted organisms that might well be mother nature's secret weapons to fight climate change.

Considered the "tree" of coastal ecosystems, seaweed uses photosynthesis to pull massive amounts of carbon from the atmosphere -- with some varieties capable of absorbing five times more carbon dioxide than land-based plants.

Seaweed is one of the fastest growing plants in the world; kelp, for example, grows up to 9-12 feet long in a mere three months. This turbo-charged growth cycle enables farmers to scale up their carbon sinks quickly. Of course, the seaweed grown to mitigate emissions would need to be harvested to produce carbon-neutral biofuels to ensure that the carbon is not simply recycled back into the air as it would be if the seaweed is eaten. The Philippines, China, and other Asian countries, which have long farmed seaweed as a staple food source, now view seaweed farms as an essential ingredient for reducing their carbon emissions.

Oysters also absorb carbon, but their real talent is filtering nitrogen out of the water column. Nitrogen is the greenhouse gas you don't pay attention to -- it is nearly 300 times as potent as carbon dioxide, and according to the journal Nature, the second worst in terms of having already exceeded a maximum "planetary boundary." Like carbon, nitrogen is an essential part of life -- plants, animals, and bacteria all need it to survive -- but too much has a devastating effect on our land and ocean ecosystems.

The main nitrogen polluter is agricultural fertilizer runoff. All told, the production of synthetic fertilizers and pesticides contributes more than one trillion pounds of greenhouse gas emissions to the atmosphere globally each year. That's the same amount of emissions that are generated by 88 million passenger cars each year.

Presented by

Brendan Smith is an oysterman, co-founder of Voices for a Sustainable Future, and senior fellow at the Progressive Technology Project. His writing has appeared in the Los Angeles Times, The Guardian, Grist, and

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