Imagine a forest so vast that if you could pull it out of the ground and stretch it into a single line, it would measure one-tenth the diameter of the Milky Way galaxy. Such a forest exists beneath our ground. Only, this forest is made not of trees but of fungi.

Scientists have just produced the first global map of an immense underground fungal network that quietly supports most of the world’s land plants.

The fungi form microscopic thread-like structures that weave through the soil, linking themselves to plant roots in a remarkable partnership; the fungi supply vital nutrients such as nitrogen and phosphorus, while the plants pay them back with carbon-rich sugars produced through photosynthesis.

The scale of this hidden system is staggering. Researchers found that nearly 40 per cent of the world’s fungal biomass is packed into just the top 15 cm of soil in certain grasslands, especially high-altitude and seasonally flooded ecosystems such as Florida’s Everglades. These underground fungal highways help lock away enormous amounts of carbon, making undisturbed grasslands some of the planet’s most dependable carbon sinks.

The fungi are voracious carbon collectors. One estimate suggests they absorb around 4.3 billion tonnes of carbon dioxide equivalent every year — roughly 11 per cent of humanity’s fossil fuel emissions in 2021.

But there is a worrying twist. The new map shows that many farming practices are tearing apart this hidden world. Topsoil in croplands contains, on average, only about half the fungal density found in healthier ecosystems — yet another instance of humankind destroying itself.

Published on June 15, 2026