Earth's fungal network stores 300 megatons of carbon: new global map shows grasslands are key

A new study published in Science maps the global reach of arbuscular mycorrhizal fungal networks for the first time. Researchers estimate the top 15 centimeters of soil contain about 110 quadrillion kilometers of fungal filaments and roughly 300 megatons of carbon in living fungal biomass. These networks transport about 4 billion tons of CO2 equivalent into soils each year, roughly 11 percent of human-related emissions. Grasslands emerged as the strongest reservoirs, holding an estimated 40 percent of global AM fungal biomass. Croplands showed network densities about 47 percent lower than non-cropland soils, likely due to fertilizer and fungicide use. The findings give land managers and conservation planners a clearer baseline for protecting underground carbon storage systems and targeting grassland preservation.