For as long as we have been building the internet, another network has been running beneath us — older, larger, and until now, almost entirely invisible. We have mapped the surface of Mars, traced the filaments of dark matter across the observable universe, and built data centers the size of villages to hold our photographs and idle thoughts. But we did not know, until this month, the full extent of the fungal web that holds the living world together.
In a paper published in Science on June 12, 2026, an international team led by researchers at the University of Sheffield, AMOLF, and the MiCRop consortium has produced the first global map of arbuscular mycorrhizal — AM — fungal networks. The numbers they found are the kind that make you stop and look at the ground beneath your feet with a new kind of vertigo. These networks stretch for roughly 110 quadrillion kilometers. If you prefer your distances in astronomical units, that is nearly a billion times the distance from Earth to the Sun. The biomass of this hidden architecture is about 300 megatons of carbon — and it is not dead infrastructure. It is alive, trading, and in constant negotiation with the roots of roughly seventy percent of all plant species on Earth.
The relationship is ancient and simple: the fungus extends its thread-like hyphae far beyond the reach of any root, gathering water and phosphorus from soil the plant cannot access. In return, the plant pays in carbon — sugars it has pulled from the air through photosynthesis. The fungus is a broker. The plant is a client. The soil is the market. And the scale of this exchange is staggering. These networks move approximately four billion tons of carbon dioxide into soils every year, roughly equivalent to eleven percent of human-related emissions. They are not merely supporting the biosphere. They are regulating its chemistry.
What strikes me most is not the scale but the invisibility. We have known about mycorrhizal relationships for over a century. Individual studies have measured them in forest plots and grasslands. But no one had stepped back far enough to see the whole fabric — perhaps because the whole fabric only exists underground, and we are creatures of light and surfaces. The study used machine learning trained on robotic imaging of living fungal hyphae, calibrated against more than sixteen thousand soil cores from around the world. The result is a map of something that has been there for hundreds of millions of years, quietly stitching the continents together while we built our own networks of glass and copper and satellites, convinced that connectivity was our invention.
The map comes with a warning. Grasslands — which hold about forty percent of the planet’s AM fungal biomass — are among the least protected ecosystems. Ninety-five percent of the identified biodiversity hotspots for these fungi fall outside protected areas. Agricultural land, which covers an ever-growing fraction of the habitable world, shows roughly fifty percent lower network density than wild soil. We are not exactly destroying this web; we are thinning it, simplifying it, replacing its dense, ancient mesh with something weaker and more fragile, without ever having known what we were touching.
There is something almost embarrassing about the timing. In the same month that billionaires promise to build brain-computer interfaces and AI companies race to create reasoning machines, a team of ecologists reminds us that we did not yet know how much fungus was under the wheat fields of Kansas or the grasslands of the Pampas. The most sophisticated network on Earth is not the internet. It is not the blockchain. It is not the neural network running on a cluster of GPUs. It is a biological internet older than the dinosaurs, and we have spent the last decade arguing about digital governance while ignoring the soil governance that quietly feeds us all.
Toby Kiers, one of the lead authors, put it plainly: fungi have been ignored in climate and conservation efforts for too long. Now is the time to change that trajectory. She is right, but I suspect the change will be slow. We are not good at protecting what we cannot photograph. A forest canopy is easy to love. A wolf in Yellowstone is a symbol. A fungal thread in the dark is just — a thread. It does not howl. It does not change color in autumn. It does not fit neatly into a documentary shot. It simply holds the world together, one phosphorus swap at a time, while we look elsewhere.
The thread held a billion suns. And we are only just learning to see it.
Sources: MiCRop Consortium / SPUN, Scientific Frontline, Science