The number and changing global distribution of seagrass-proximate people

Seagrass meadows are increasingly recognised as critical natural capital, yet global seagrass conservation still lacks a basic human geography. Building on examples from forests, here, we provide the first global estimate of seagrass-proximate people, defined as people living within specified distances of known seagrass. We combined a global distribution layer of known, mapped and observed seagrass with multitemporal 1 km GHS-POP population grids to estimate populations within 1 km, 5 km and 10 km of known seagrass from 1975 to 2020, with projections to 2030. In 2020, at least 53.4 million people lived within 1 km of known seagrass, 194.8 million within 5 km, and 352.9 million within 10 km. The number living within 5 km almost doubled between 1975 and 2020, increasing by 94.2 million people, and is projected to reach 214.4 million by 2030. More than 62% of seagrass-proximate people lived in tropical bioregions, where seagrass biodiversity and ecosystem-service importance are high. Country-level patterns revealed two policy geographies, large absolute populations near seagrass in countries such as the Philippines, United States, Italy, Indonesia and Spain, and nationally pervasive seagrass proximity in many Small Island Developing States. Our estimates are conservative because global seagrass mapping remains incomplete. Proximity is not dependence, but it identifies where human wellbeing, coastal development and seagrass conservation are most likely to intersect. These results establish a spatial baseline for integrating people, ecosystem services and justice into global seagrass conservation and policy.