Threads of Earth’s Underground Fungal Networks Are Long Enough to Reach Beyond the Solar System

A global survey of arbuscular mycorrhizal fungal networks reveals a staggering 110 quadrillion kilometers of fungal threads beneath Earth's surface, researchers reported Thursday in Science. If stretched into a single line, these ultra-thin filaments would extend nearly a billion times the distance from Earth to the sun.

Arbuscular mycorrhizal fungi form symbiotic relationships with plant roots across terrestrial ecosystems. The fungal threads extract water and nutrients from soil, transferring them to plants in exchange for carbohydrates produced through photosynthesis. This exchange sustains roughly 80 percent of plant species globally, making these networks foundational to terrestrial food webs and carbon cycling.

The study quantifies the fungal biomass and distribution across different biomes, revealing how these hidden networks concentrate in forests, grasslands, and croplands. The research carries implications for understanding soil health, plant resilience, and carbon storage capacity in the ground. Soil fungi sequester carbon as they grow and decompose, influencing how much carbon remains locked in earth versus released into the atmosphere.

Climate models have historically underestimated the role of soil microorganisms in carbon cycling. This comprehensive mapping provides data scientists need to refine predictions about how ecosystems respond to warming temperatures, drought, and land-use changes. As agricultural soils degrade and forests face pressure from logging and conversion, these fungal networks decline, potentially reducing both plant productivity and soil carbon storage.

The findings underscore an often-overlooked dimension of ecosystem function. While above-ground conservation focuses on visible species, these subterranean networks operate as critical infrastructure for planetary health. Their biomass and distribution patterns suggest that protecting fungal communities through reduced soil disturbance, diverse crop rotations, and forest preservation directly affects carbon sequestration capacity and food security.