Ocean farming is featured as one of Drawdown’s “coming attractions”—climate solutions that weren’t ready for prime time when the book appeared, but could make a difference by mid-century. 

Ocean-based fish farms have drawn sharp public criticism for their harmful effects on local ecosystems and the poor quality of food they produce, but the scenario Drawdown presents is different from the industrial aquaculture so frequently in the headlines. These are small, sustainable farms where compatible crops are grown not just for use as food and fuel, but for their value in restoring the environment and reversing climate change.

“Environmentalists have long struggled with the perils of overfishing, climate change, and pollution. What if we have it backward?” the authors ask. “What if the question is not how we can preserve the wildness of our oceans, but how the oceans can be developed to protect them and the planet?”

Seaweed and shellfish both show early promise as anchor crops, especially when they’re cultivated in proximity to one another, Drawdown states. Oysters farms filter nitrogen from surrounding waters—and some forms of nitrogen are around 300 times more potent than carbon dioxide as greenhouse gases. Floating oyster reefs are also being explored as living barriers that protect coastal areas from hurricanes and sea level rise.

Seaweed is similarly useful. “Seaweed pulls carbon from the atmosphere and the water, with some varieties capable of absorbing five times more carbon dioxide than land-based plants,” Drawdown explains. “Seaweed farms also have the capacity to grow massive amounts of nutrient-rich food and provide a clean replacement for biofuels.”

Ocean farms don’t need fertilizers or fresh water, and they don’t prompt farmers to deforest land in order to cultivate crops. While developing the oceans may spark controversy, especially given the history of human interventions in wild spaces, proponents believe thoughtful, biodiverse aquaculture may do more to protect the planet than to harm it.