Earth's Hidden Climate Regulators
New Global Study Maps 110 Quadrillion-Kilometer Fungi Networks Crucial for Climate
Key Points
The study links the fungi-plant partnership to deep time, saying arbuscular mycorrhizal networks have been forming for roughly 475 million years, while another study account describes the symbiosis as “quite ancient, about 450 million years old.”
Agriculture’s impact is quantified: the researchers found cropland network densities average 47.3% lower than in wild ecosystems, and noted that practices such as tilling “literally rip” soil and disrupt the plant–fungus symbiosis; the reporting also flags fertilizers or fungicides as additional disruptors.
In especially healthy conditions, AM fungi are reported to dramatically improve plant acquisition: their webs can boost plants’ root “foraging area by 100 times” and provide “over 80 percent” of needed phosphorus.
Beyond total storage, the reporting adds an annual carbon flux estimate: the fungi are said to move around 4 billion tons of carbon dioxide into the soil each year—described as about 11% of human-produced emissions.
The researchers also frame the scale of fungal biomass in terms of human comparison, estimating the networks’ carbon mass is “equivalent to about five times that of all living humans combined.”
Scientists have published the first global map of Earth's underground fungal highways — and the scale is almost impossible to imagine. The web of arbuscular mycorrhizal (AM) fungi stretches roughly 110 quadrillion kilometers, enough to travel from Earth to the sun and back nearly a billion times, according to New Scientist.
Published in the journal Science, the study used machine-learning models trained on more than 16,000 soil samples to chart these fungi across every major ecosystem on Earth. The networks weigh around 300 megatons and move about 4 billion tons of CO2 into the soil every year — roughly 11% of all human-caused emissions, The Guardian reported.
A 475-Million-Year Partnership Now Mapped for First Time
AM fungi are not new. They have been forming symbiotic relationships with plant roots for roughly 475 million years, helping the first plants colonize dry land, according to The Guardian. Yet until now, no one had a global picture of where these networks are densest or how much they collectively weigh.
Researchers from Vrije Universiteit Amsterdam and the Society for the Protection of Underground Networks (SPUN) synthesized data from 322 previous studies and over 16,000 soil cores. Lead author Dr. Justin Stewart noted that "there could be up to 10 meters of mycorrhizal network in just a teaspoon of soil," Nautilus reported. The result is an interactive global atlas — the first of its kind.
How Fungal Webs Feed Plants and Store Carbon
The fungi act as a hidden supply chain for plants. In healthy conditions, their webs can expand a plant's root foraging area by 100 times and deliver over 80% of the phosphorus a plant needs, according to Head Topics. In return, plants feed the fungi carbon produced through photosynthesis.
That carbon exchange adds up fast. The fungi move around 4 billion tons of CO2 into soils each year. The networks' total carbon mass is equal to about five times the mass of all living humans combined, The Guardian reported. Co-author Dr. Toby Kiers said the findings show soil should be seen not as dirt but as a complex biological transport system.
Farming Practices Are Ripping These Networks Apart
The map also delivers a stark warning about agriculture. Cropland fungal network densities are 47.3% lower on average than in wild ecosystems, The Guardian found. Researchers say tilling literally rips the soil apart, severing the fungal threads that plants rely on. Synthetic fertilizers and fungicides add further damage.
The loss matters beyond soil health. When fungal networks are destroyed, plants need more synthetic inputs to get the same nutrients. Scientists say switching to no-till farming could help rebuild networks — and reduce the need for costly fertilizers at the same time, according to Infonasional.
Hotspot Map Could Drive New Soil Conservation Policy
The study identifies specific high-density hotspots — including the South Sudan flooded grasslands, the Florida Everglades, and the Tibetan Plateau — that may now be targeted for protection similar to tropical rainforests, Nautilus reported. Researchers plan to bring the data to the UN Desertification Summit in Mongolia later in 2026.
Conservationists say current carbon credit systems are incomplete because they ignore the 11% of annual human emissions that these fungi pull into the soil. Dr. Kiers called for "a big movement now to not only restore communities above ground... but also to restore underground fungal communities," according to New Scientist.
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