Cultivating grains in the ocean could help coastal regions grow food on land lost to rising seas.
As climate change causes sea levels to rise, farmland across the globe is at risk of becoming unusable. But scientists believe there may be a surprising solution growing underwater: cultivating grains in the ocean.
Researchers are now exploring how seagrass, a marine plant known for its ability to grow in salty water, could produce food even as traditional farmland floods. This approach could help the world prepare for future sea level rise while producing sustainable, low-emission food.
According to a recent study published in Ambio, sea levels could rise enough to flood over 620,000 square kilometres of land by the year 2100, even with strong climate action. That’s an area almost the size of Ukraine. Of that total, about 80,000 square kilometres could become the perfect zone for cultivating grains in the ocean.
The lead author of the study, Dr. Marieke M. van Katwijk of Radboud University in the Netherlands, believes farmers will need to adapt their methods to survive in this wetter world. Instead of fighting the water, they could work with it by growing grain underwater using seagrass meadows.
Seagrass is a marine plant found along coastlines around the world. Some species, such as eelgrass, produce small, edible seeds that resemble grains. These seeds are sometimes called “sea rice,” although their composition is closer to wheat than to actual rice.
For centuries, Indigenous groups such as the Seri people of Mexico have used this ocean grain to bake bread. It has a flavour similar to rye and is known to be a nutritious option. Now, scientists believe that cultivating grains in the ocean could provide a way to scale up this ancient food source in modern times.
Wild eelgrass already produces between 3 and 6.5 tons of edible grain per hectare—roughly equal to the 4.7 tons per hectare of modern rice farms. That means if seagrass were grown across the 80,000 square kilometres of land likely to be lost to rising seas, the world could produce up to 52 million tons of ocean-grown grain each year. That’s about 3 to 7% of the world’s current rice supply.
This potential makes cultivating grains in the ocean a real option for boosting food security, especially in coastal areas hit hard by climate change.
Unlike many traditional crops, seagrass doesn’t need chemical fertilizers to thrive. It naturally recycles nutrients in the water, making it ideal for eco-friendly farming. It also stores carbon at an impressive rate. Some seagrass meadows can trap up to 1,900 kilograms of carbon per hectare per year—much faster than tropical forests.
This makes cultivating grains in the ocean a promising zero-emission farming method. While transporting and harvesting the grain will still produce some emissions, these are likely to be offset by the carbon stored in the seagrass beds.
Seagrass meadows support biodiversity. They provide shelter and food for many species of fish, shellfish, and marine life. In this way, seagrass farms could boost commercial fishing by creating healthy habitats for young fish.
These ocean farms could also serve as natural barriers, reducing erosion, protecting coastlines from storms, and maintaining the strength of coastal ecosystems.
While cultivating grains in the ocean offers major benefits, it’s not without challenges.
Right now, no seagrass varieties have been domesticated for large-scale farming. Scientists are still working on identifying the best seeds and developing methods for planting, harvesting, and storing the grains.
There’s also a serious need to protect wild seagrass meadows. These natural habitats are shrinking globally due to pollution, dredging, and other human activities. Experts stress that seagrass farms must not damage wild ecosystems. Farms should never replace or harvest from wild meadows, and any new ocean agriculture should support—not harm—marine biodiversity.
Dr. van Katwijk argues that because ocean grain farming is still in early development, now is the time to build it the right way. She believes farmers can learn from the mistakes of land-based industrial agriculture by designing nature-friendly systems from the start.
Although farming the sea may sound futuristic, the time to act is now. Sea levels are rising. Saltwater is pushing into farmland. Coastal communities are being squeezed between climate threats and food insecurity.
By investing in research and pilot projects now, the world can prepare for a future where cultivating grains in the ocean becomes a regular part of food production. With careful planning, seagrass farms could support local economies, lower emissions, and provide a reliable food source for millions.
This isn’t just about food. It’s about adapting to the new climate reality while keeping people fed and the planet healthy.
