Beneath your feet, a hidden fungal superhighway stretches 68 quadrillion miles, nearly a billion times the distance from Earth to the Sun. Scientists have mapped this underground network for the first time, revealing a living infrastructure that quietly sustains plant life and helps regulate the climate.
A network longer than a billion trips to the Sun
Researchers estimate that global topsoils contain roughly 110 quadrillion kilometers of arbuscular mycorrhizal fungi, or AM fungi. These thread-like structures, called hyphae, form partnerships with about 70 percent of plant species worldwide. Plants give the fungi carbon from photosynthesis, and the fungi supply plants with nutrients and water. The networks move an estimated 4 billion tons of carbon dioxide equivalent into soils each year, which equals about 11 percent of all human related carbon emissions.
Where the fungi thrive and where they vanish
Grasslands hold roughly 40 percent of Earth's AM fungal infrastructure. Particularly dense networks appear in the flooded grasslands of South Sudan, the Everglades in Florida, and the Tibetan plateau. But large agricultural croplands show about 50 percent lower network densities on average. Researchers warn that less dense fungal networks could reduce a soil's ability to store carbon, cycle nutrients, and withstand environmental stress.
The study, published in Science, builds on earlier work. In 2025, researchers published a global analysis of underground mycorrhizal fungal diversity in Nature and launched a digital platform called the Underground Atlas to identify likely biodiversity hotspots beneath the surface. The new maps go further by estimating the physical density and worldwide distribution of the fungal networks themselves.
Scientists released an interactive visualization alongside the research, allowing users to explore the scale of this hidden infrastructure. The maps are expected to help researchers and policymakers identify areas where these fungal networks are thriving and where they may be under threat.
This discovery reframes what lies beneath our feet. The fungal superhighway is not a metaphor. It is a measured, mapped reality that moves carbon, supports ecosystems, and connects life across continents.
