Jiwei Li still remembers the satellite image that changed everything—a patch of vibrant green seagrass glowing beneath the turquoise waters off Papua New Guinea, a detail so small on the map but enormous in meaning. For the first time in history, scientists have produced a complete, high-resolution global map of seagrass ecosystems, revealing not only where these vital plants thrive but also where they’re vanishing—and where they’re coming back. Led by Arizona State University’s Center for Global Discovery and Conservation Science, this breakthrough fills a decades-long blind spot in marine conservation and could redefine how we protect coastlines, fight climate change, and sustain ocean life.
Seagrass is often overlooked, mistaken for seaweed or simply invisible beneath the waves. But it’s a powerhouse: a flowering plant with roots that stabilize seabeds, filter pollutants, and shelter countless marine species—from juvenile fish to sea turtles. It’s also a climate champion. The new data reveals that seagrass stores an estimated 640 teragrams of carbon in the top 30 centimeters of sediment alone—equivalent to the annual emissions of 500 million cars. "When we're talking about seagrass, you can think about it as a rainforest underwater," says Li, an assistant professor in the School of Ocean Futures. "It's foundational for all the food webs in coastal regions."
Until now, global seagrass monitoring has been hampered by patchy data and inconsistent methods. The team’s solution was groundbreaking: they trained an AI model using thousands of underwater “ground truth” observations collected by divers worldwide, who confirmed the presence of seagrass, coral, sand, and other seabed features with precise GPS tags. This data trained the model to identify seagrass in satellite imagery at a resolution of just 10 square meters—fine enough to detect small meadows and track changes over time. Powered by ASU’s supercomputers Agave and Sol, the system analyzed millions of images to produce the first consistent, high-resolution map of seagrass across the planet.
The results are both alarming and hopeful. The study found that seagrass is being lost at a rate of 1% per year—a significant decline—but it also identified areas where seagrass is recovering, offering real-world blueprints for restoration. These recovery zones could become models for conservation strategies, especially as coastal development and climate change accelerate habitat loss. With precise locations now known, policymakers and local communities can target protection efforts more effectively, from limiting boat anchoring to restoring degraded areas.
This map isn’t just a scientific achievement—it’s a tool for action. As part of the Allen Coral Atlas project, it will be used to guide marine protection policies, carbon accounting, and fisheries management around the world. For Li and his team, the mission is clear: bring seagrass out of the shadows and into the spotlight of global conservation. "This work represents a game changer," he says. And with every pixel mapped, the ocean’s green lungs are finally getting the attention they deserve.