This story was originally published by Inside Climate News and is reproduced here as part of the Climate Desk collaboration.

Hidden underground around the world lie 110 quadrillion kilometers of arbuscular mycorrhizal fungal networks—webs of ultrathin threads that, if connected in a single line, would stretch almost a billion times the distance between the Earth and the sun, according to new research published in Science on June 11.

These fungal communities form intimate relationships with the roots of plants, which they provide with nutrients like phosphorus and nitrogen in exchange for carbon, 1 billion tons of which the networks sequester underground annually, previous research has found. If the fungal network wasn’t storing it, that carbon would be warming the atmosphere.

But those networks have never been mapped globally until now. The new study led by Society for the Protection of Underground Networks (SPUN), an organization founded to map mycorrhizal fungi networks, used a combination of literature review, soil samples from around the globe, machine learning, and laboratory testing to estimate the distribution and mass of these systems and map where they are densest.

“This is the moment where we went from knowing that this system exists to really knowing where it is, how dense it is and where it’s been,” said Toby Kiers, executive director and co-founder of SPUN and a co-author of the study.

“You’re getting a win-win. The plants are growing better, and carbon’s being drawn down. ”

For decades,........

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