Scientists Create First Global Map of Earth's Underground Fungal Networks, Revealing 110 Quadrillion Kilometers of Fungal Filaments

Published in the journal Science, the study represents the first attempt to map and quantify the physical density and global distribution of arbuscular mycorrhizal (AM) fungi, an ancient group of soil fungi that form symbiotic relationships with approximately 70% of all land plant species. Using data from more than 16,000 soil cores drawn from 322 prior studies, robotic imaging of over 300,000 living fungal hyphae, and machine-learning models trained across diverse biomes, the international research team estimated the total length of AM fungal networks at roughly 110 quadrillion kilometers and their total carbon mass at approximately 300 megatons — four to six times the mass of all living humans. The global map, built in collaboration with data visualization designer Moritz Stefaner and available as an interactive tool, resolves estimates down to each square kilometer of terrestrial land. Grassland ecosystems — including the Florida Everglades, South Sudan's Sudd wetlands, and the Tibetan Plateau — were identified as containing the densest networks, accounting for roughly 40% of global AM fungal biomass, yet these regions are among the least protected on Earth and are being converted to farmland four times faster than forests. The study documents that cropland soils show approximately 50% lower fungal network densities than wild ecosystems, driven by tillage, heavy fertilizer use, and fungicide application. Researchers emphasized that the findings are intended as living documents, supplemented by 'maps of ignorance' highlighting data-sparse regions, and that results will be presented to policymakers at the United Nations desertification summit in Mongolia in August 2026.