More than 16,000 soil samples, combined with machine learning and a high-resolution imaging robot, let researchers estimate the global scale of the underground network.
300 megatons of carbon are stored in those fungi, the study said, making them a major overlooked carbon reservoir that supports more than 70% of terrestrial plant species.
Grasslands emerged as especially dense hotspots for the networks, a finding that points to conservation gaps because those ecosystems often receive less protection than forests.
The map expands earlier work on mycorrhizal links between trees to a planetary view, underscoring how much of Earth’s nutrient exchange and carbon storage happens belowground.
Can we feed humanity without destroying the vital fungal networks that have supported plants for 460 million years?
Fungi absorb carbon but also toxic PFAS. Is this vast underground network a hidden threat to our food supply?
Ninety percent of Earth's 'wood-wide web' is unprotected. How can we save this invisible world beneath our feet?
Mapping 110 Quadrillion Kilometers: The Hidden Fungal Networks Shaping Earth's Climate, Food Security, and Future
Overview
In June 2026, the Society for the Protection of Underground Networks (SPUN) unveiled the first comprehensive map of Earth's underground fungal networks, revealing an incredible 110 quadrillion kilometers of living threads beneath our feet. Spearheaded by researchers from SPUN and supported by major philanthropic organizations, this achievement offers an unprecedented look at what scientists now call Earth's hidden circulatory system. These intricate networks, mainly made of arbuscular mycorrhizal fungi, have shaped life on Earth for hundreds of millions of years by forming vital symbiotic relationships with plants, highlighting their fundamental role in ecosystem health and climate regulation.