Beneath Our Feet Lies a Fungal Superhighway Stretching 68 Quadrillion Miles — Scientists Just Mapped It

Every step you take outdoors passes over something almost impossible to picture. Beneath the soil, hidden from view and largely ignored by science until very recently, lies a sprawling web of fungal threads so vast that laying it end to end would stretch roughly 110 quadrillion kilometers, or about 68 quadrillion miles. That is not a typo or an exaggeration dressed up for a headline. It is the central finding of a landmark study published in the journal Science in June 2026, and it represents the first time anyone has attempted to map the true scale and distribution of this hidden infrastructure across the entire planet.

The fungi in question are known as arbuscular mycorrhizal fungi, and if that name means nothing to you, it should, because these organisms form partnerships with roughly seventy percent of all plant species on Earth. They are, in the words of one of the study's lead researchers, something close to a circulatory system for the planet's soils. Understanding what this newly mapped network actually does, why its scale matters, and what is putting it at risk offers a genuinely different way of thinking about plant life, climate stability, and the food we grow.

What Mycorrhizal Fungi Actually Are

Mycorrhizal fungi live in soil and form close partnerships with the roots of plants, and arbuscular mycorrhizal fungi specifically grow directly into plant root cells rather than simply wrapping around them. The relationship at the heart of this partnership is a trade. The fungi extend their thread-like filaments, called hyphae, deep into pockets of soil that plant roots alone could never reach, and from there they extract water along with hard-to-access nutrients like nitrogen and phosphorus. In exchange, the plant shares some of the sugars and carbon it produces through photosynthesis, effectively paying the fungi for services it cannot easily provide for itself.

This arrangement is so widespread and so fundamental that scientists increasingly describe these fungal networks as ecosystem engineers rather than simply soil organisms. They act, as one researcher put it, like a circulatory system running beneath the surface of the Earth, moving resources between countless plants in ways that are functionally similar to how blood vessels move nutrients through a human body. The comparison is not just poetic. In just the top fifteen centimeters of soil, scientists estimate that every single square centimeter contains around 4.4 meters of hyphae, a network roughly fifty times longer than the fine root hairs of the very plants it partners with.

How Researchers Mapped an Invisible World

Mapping something this vast and this hidden required an unusual combination of old-fashioned fieldwork and cutting-edge computing. An international team, working in collaboration with the Society for the Protection of Underground Networks, assembled measurements from more than 16,000 soil cores collected from locations spanning the globe, from deserts and tundra to dense forests and open grasslands. Because it is physically impossible to dig up and sample every patch of soil on Earth, the researchers then built machine-learning models that used environmental data, including climate, vegetation and soil characteristics, to predict fungal network density in places that had never been directly sampled.

To make sure those predictions reflected reality, the team calibrated their models using an unusual form of ground truth: robotic imaging of more than 300,000 living arbuscular mycorrhizal hyphae grown in laboratory conditions, developed in collaboration with a physics research group studying biological behavior. The result of all this work, published alongside an interactive visualization that allows anyone to explore the data, is the first global estimate of just how much of this fungal infrastructure actually exists, and where on Earth it is most concentrated.

Why 110 Quadrillion Kilometers Is a Number Worth Sitting With

It is difficult for any human mind to meaningfully grasp a number as large as 110 quadrillion kilometers, so it helps to use the comparisons the researchers themselves have offered. That total length is almost a billion times the distance between the Earth and the Sun. It is the kind of figure that sounds more like an estimate of something cosmic than something living in the dirt beneath a backyard or a farm field.

The distribution of this network across the planet is just as revealing as its overall scale. Grassland ecosystems, rather than the rainforests most people might assume, contain roughly forty percent of Earth's entire arbuscular mycorrhizal fungal infrastructure, making them an unexpectedly central piece of this underground puzzle. The researchers identified particularly dense concentrations in specific places, including the flooded grasslands of South Sudan, the Everglades in Florida, and the high-altitude grasslands of the Tibetan plateau. These are not the locations most people would point to first when asked where Earth's most important ecological infrastructure might be hiding, which is part of what makes this mapping effort so valuable.

The Carbon and Nutrient Highway Running Beneath Every Forest

Beyond their sheer scale, what makes these fungal networks so significant is the active role they play in moving resources between living things, often across surprising distances. Because a single network of hyphae can connect the roots of multiple different plants and trees simultaneously, nutrients, water and even carbon compounds can move between organisms that are not directly touching one another, effectively allowing a forest or grassland to function more like an interconnected system than a collection of separate, competing individuals. A tree with abundant resources can, in effect, share some of that surplus with a struggling neighbor through the same underground fungal connections that both plants rely on for nutrients.

This movement of resources has consequences that reach all the way up to the planet's climate system. The study estimates that arbuscular mycorrhizal fungal networks move approximately four billion tons of carbon dioxide equivalent into soils every single year, a figure equivalent to roughly eleven percent of all human-caused carbon dioxide emissions. In total, these networks are estimated to hold around 300 million tons of carbon within their living structures. Soil, in other words, is not simply a passive container that holds carbon. It is an active destination that these fungal highways are constantly delivering carbon toward, year after year, largely without any human intervention or awareness that the process is even occurring.

What Is Putting This Hidden World at Risk

For something this large and this important, the threats facing mycorrhizal networks are surprisingly direct and surprisingly familiar. The study found that large agricultural croplands have, on average, roughly fifty percent lower fungal network density compared with more natural ecosystems, a gap that points squarely toward how modern industrial farming disrupts this underground infrastructure. Aggressive tillage physically tears through soil and severs fungal hyphae, while heavy machinery compacts soil in ways that limits how far fungal networks can spread and how effectively they can colonize plant roots in the first place.

Chemical inputs compound the damage. Pesticides and fungicides, applied to protect crops from pests and disease, do not distinguish between harmful organisms and the beneficial fungi quietly working underground, and research has found that fungicide application alone can reduce phosphorus uptake in croplands by more than forty percent. Excessive use of synthetic fertilizers creates a separate problem: when plants can access nutrients easily and artificially through fertilizer, they have less incentive to maintain their costly partnership with mycorrhizal fungi, gradually weakening a relationship that took these organisms hundreds of millions of years to establish. Comparisons between organically managed and conventionally managed farmland have found striking differences in fungal complexity, with one study identifying twenty-seven highly connected keystone fungal species in organic fields compared with none at all in conventionally managed ones. Beyond agriculture, deforestation, construction, and soil erosion all compound the damage, stripping away the very habitat these networks need to survive and regenerate.

Perhaps most concerning is how little of this underground world currently falls under any kind of formal protection. A related global mapping effort focused on fungal biodiversity found that less than ten percent of mycorrhizal fungi biodiversity hotspots fall within existing protected areas, meaning that even where these networks are most diverse and most valuable, conservation policy has largely failed to notice or account for them.

What Protecting This Network Would Actually Mean

The case for protecting mycorrhizal networks rests on two of the most pressing challenges facing humanity simultaneously: climate stability and food security. On the climate side, a fungal infrastructure already moving roughly four billion tons of carbon dioxide equivalent into soils every year represents an enormous natural climate regulation system that is currently operating almost entirely without active human management or protection. Preserving and restoring these networks, rather than continuing to degrade them through aggressive land use, could help maintain or even enhance one of the planet's significant natural carbon sinks at a moment when every available avenue for drawing down atmospheric carbon matters.

On the food security side, the stakes are just as direct, if less widely appreciated. Nearly all of the world's major food crops depend on mycorrhizal partnerships to access nutrients and water efficiently, and to withstand stresses including drought, pathogens and soil erosion. When these networks are degraded, crops do not simply lose a helpful bonus; they become measurably more dependent on costly chemical fertilizers and more vulnerable to the very droughts and soil degradation that a changing climate is making more frequent. Healthier fungal networks function as a kind of natural drought insurance for agriculture, an insurance policy that becomes more valuable, not less, as weather patterns grow more unpredictable.

Practical steps toward protecting this infrastructure are not exotic or especially costly. Reducing tillage, cutting back on unnecessary fertilizer and pesticide use, incorporating diverse crop rotations, and supporting reforestation and habitat restoration projects have all been shown to help fungal networks recover and thrive. None of these changes requires inventing new technology. They require recognizing that the soil beneath a farm field or a forest floor is not an inert backdrop to the visible parts of an ecosystem, but an active, living, almost unimaginably vast network that is already doing an enormous amount of quiet work to keep both plants and the planet's climate functioning.

The Bottom Line

It took scientists until 2026 to produce the first real map of something that has likely been operating beneath nearly every step taken on land for hundreds of millions of years. That gap between how long these networks have existed and how recently humanity began to understand their true scale says something important about how much remains unknown about the systems that sustain life on Earth. A web of fungal threads stretching 110 quadrillion kilometers, moving billions of tons of carbon and supporting most of the plant life people depend on for food, was hiding in plain sight the entire time, simply because no one had looked at it the right way, or with the right tools, until now. What happens to that network in the decades ahead, whether it continues to be quietly degraded by agriculture and development or is recognized and protected as the foundational infrastructure it actually is, may matter more to climate stability and food security than most people have ever had reason to consider.

*This article is for informational purposes only. Research data is sourced from the journal Science, the Society for the Protection of Underground Networks (SPUN), ScienceDaily, National Geographic, and EurekAlert.*