Farms of the future face rising sea levels, flooding of fertile land, and increasingly saline soils that will undermine yields. But what if farmers could work with this changing landscape?
A new perspective published in Ambio explores how growers in some landscapes could switch to seagrass in an increasingly marine future. Cultivated at scale, seagrass meadows could produce grain in quantities equivalent to 7% of global rice production, with potentially zero emissions, the new perspective says.
Plants in this large marine family, such as eelgrass, produce plump seeds tucked inside underwater shoots. Colloquially known as ‘sea-rice’, this oceanic grain has long been a source of food in Indigenous cultures. Despite the name, the grain is actually similar to wheat, and for centuries has been used by the Seri people of Mexico to make bread, with flavors that are reportedly similar to rye. “The novelty in this paper is to combine [that knowledge] with sea level rise and the solutions we need to adapt our landscapes,” says lead author Marieke M. van Katwijk, who studies seagrass restoration and ecology at Radboud University in the Netherlands, a country that itself is vulnerable to sea level rise.
Her paper shows that even with the most ambitious climate action, there will be global warming of at least 1.5 to 2 C that will leave 620,000 square kilometers of land vulnerable to flooding by 2100. Compared to today, that will increase the current area of sea-influenced land by 80,000 square kilometers, which could hypothetically support seagrass cultivation.
Eelgrass has not been domesticated, yet even wild varieties can currently produce between 3 and 6.5 tons of edible grains per hectare—comparable to the 4.7 tons per hectare produced on average by domesticated rice. Meanwhile, breeders could use its broad genetic diversity to develop higher-yielding cultivars. Eelgrass’s wide distribution, with meadows stretching from North Africa, to Europe, Asia and North America, means it’s also tolerant to ranging levels of salinity and temperature differences, which equips sea rice for a changing world.
The perspective goes on to say that due to the nutrient-cycling abilities of seagrass, high grain yields wouldn’t require chemical fertilizers. And, farmers could lean into the natural strengths of this marine plant as a significant carbon store. Depending on species and location, meadows can sequester between 50 and 1900 kilograms of carbon per hectare each year, doing so dozens of times faster than tropical forests.
While the process of seeding, harvesting, and transporting sea rice could produce greenhouse gas emissions like other types of agriculture, van Katwijk notes that combined with the future decarbonization of these processes, the carbon reserves beneath seagrasses would very likely fully offset those outputs.
That’s not to mention the wider ecosystem benefits that seagrasses provide, including as harbors of biodiversity that also help shore up commercial fisheries. Overall, if eel grasses were cultivated across the 80,000 square kilometers of the new coastal seascape that will be engineered by future rising oceans, farmers could produce up to 52 million tons of grain annually—that’s about 3 to 7% of all the rice the world farms each year. This is “such an elegant solution—when applied in a balance between food production and ecosystem services,” van Katwijk says.
Seagrass farming is still in its infancy: there aren’t yet the right seed cultivars available to make it a commercial reality. But being at this early stage also gives us a chance to avoid the mistakes of conventional agriculture, van Katwijk believes.
It’s critical first of all that seagrass cultivation doesn’t eclipse the need to protect wild meadows, which are declining worldwide and whose restoration should be the priority, she says. Farms shouldn’t encroach on wild meadows, nor should wild meadows be used to harvest sea-rice commercially. Meanwhile, by designing farms with nature in mind, these landscapes could welcome in wildlife and support marine biodiversity. They could even incorporate carefully-managed donor schemes to help restore natural meadows and support their wild ancestors. And at the same time, sea rice would be boosting food security, by adapting to our changing world.
While seascape agriculture might seem far off, it’s something we can start preparing for now, van Katwijk says. “There are fascinating win-win opportunities for sustainable food production with zero carbon emissions that we should invest in today, to apply in the far future, when the sea level rises more.”
Van Katwiik, M. “Grain fields in sea-landscapes.” Ambio. 2025.
Photo by Daniel Von Staats/NERRS Science Collaborative
