Where Kelp Forests Meet People: An analysis of the spatial overlap among human population, global economies, and environmental threats to kelp forest ecosystems

Abstract Kelp forests, formed by large brown algae in the orders Laminariales and Fucales, are among the most widespread marine ecosystems. Despite their scale and importance to people, kelp forests remain under-recognized by the public and underrepresented in global policy and conservation agendas. We quantify the global spatial overlap between the kelp biome and human populations, economic activity, anthropogenic pressures, and projected ocean warming to assess the extent and geography of the coupling between kelp and people. We synthesised distributions of laminarian and fucoid kelp forests, explicitly distinguishing between ‘major’ kelp forests and ‘minor’ kelp forests. These distributions were intersected with global datasets on population, Gross Domestic Product (GDP), cumulative human impact, and projected sea surface temperature (SST) change to 2100. Analyses focused on populations and economic activity within 50 km of major kelp habitats. Approximately 959 million people live within 50 km of kelp forests globally (12% of global population), including 781 million adjacent to major kelp forests. These regions account for $27.6 trillion or ∼18% of global GDP and include major metropolitan centres such as Tokyo, Seoul, Los Angeles, Sydney, and several Mediterranean cities. Cumulative human pressures on kelp-associated coastlines are highest in densely populated temperate regions, particularly the Mediterranean, northwest Atlantic, and East Asia. Warming by 2100 is greatest at high latitudes, but the strongest link to people occurs in temperate regions where projected SST increases coincide with dense populations and high economic output. Our results support the idea that kelp forests are integrated into modern social–ecological systems, while overlooked in governance and funding. This global assessment identifies the tight coupling between people and kelp forests while identifying geographic risks and opportunity hotspots. Together, the work provides a foundation for communicating the role of kelp forests in society and for prioritising kelp conservation within marine conservation agendas.