Beneath every forest, every grassland, every garden, and almost every agricultural field on Earth, there is an invisible world doing something extraordinary.
It is vast — fungal networks stretch for hundreds of kilometres beneath a single hectare of healthy soil. It is ancient — mycorrhizal fungi formed partnerships with the first land plants more than 400 million years ago. And it has, until recently, been almost entirely overlooked by climate science.
That oversight is ending. And the scientist most responsible for ending it is **Dr. Toby Kiers**, an evolutionary biologist at Vrije Universiteit Amsterdam. In 2026, she was awarded the **Tyler Prize for Environmental Achievement** — widely described as the Nobel Prize of the environment — for her research into what these fungal networks actually do, and why they matter for life on Earth.
**What Mycorrhizal Fungi Are**
Mycorrhizal fungi are microscopic threads — hyphae — that form symbiotic partnerships with the roots of approximately **90% of land plant species**. The partnership is ancient and mutually beneficial: the plant provides carbon to the fungus (in the form of sugars and fats produced by photosynthesis), and the fungus provides the plant with minerals — phosphorus, nitrogen, water — that its roots alone cannot efficiently access.
The word "mycorrhizal" comes from the Greek for "fungus-root." The relationship is so fundamental that most trees, grasses, crops, and wildflowers depend on it to survive. Remove mycorrhizal fungi from the soil and most ecosystems collapse.
But what Kiers and her colleagues have spent years revealing is something beyond the basic biology of the partnership: the **carbon flows** that it sustains, and their global climate significance.
**The 13 Billion Ton Discovery**
Plants are photosynthesis machines. They draw CO₂ from the atmosphere, use sunlight to convert it into sugar, and grow. But a substantial proportion of that captured carbon — estimates range from 10% to 40% depending on the plant and conditions — doesn't stay in the plant. It flows down through the roots into the mycorrhizal network.
Some of that carbon is used by the fungi themselves. But a significant proportion is transferred into the soil — into the bodies of fungi, into organic matter, into stable soil carbon compounds that can persist for decades or centuries.
Kiers' research, combined with global modelling work published in 2023 in the journal *Current Biology*, put a number on this flow for the first time: mycorrhizal fungi receive an estimated **13 billion tons of CO₂** from plants annually. That is approximately **one-third of total global fossil fuel emissions** in any given year — an enormous carbon flux that is happening constantly, quietly, in the soil beneath our feet, and which climate models had largely failed to account for.
**How the Science Changed**
Before Kiers' work, mycorrhizal fungi were understood primarily as biological facilitators — interesting, important for plant nutrition, but not players of global significance in the carbon cycle. The fungi received attention from soil scientists and ecologists but almost none from climate scientists or policymakers.
Kiers' contribution was to move the science from qualitative to quantitative — to put numbers on the flows, to track carbon movement through fungal networks in real time, to reveal the underground system as not just biologically interesting but **climatologically critical**.
Her lab used cutting-edge isotope tracing techniques to follow individual carbon atoms as they moved from plant photosynthesis through roots into fungal hyphae and on into the soil. The work showed that the flow was large, consistent, and happening at global scale.
**The Tyler Prize and What Comes Next**
The Tyler Prize is awarded by the University of Southern California and has been presented since 1973 to scientists whose work advances understanding of the environment. Previous laureates include oceanographer Sylvia Earle and ecologist Paul Ehrlich.
Kiers, 48 at the time of the award, is the **youngest female laureate in the prize's history**.
She will receive $250,000 at a ceremony in Amsterdam on **April 23, 2026**, where she will also deliver the State of the Environment Address — an invitation to set the agenda for what comes next.
What comes next, in Kiers' vision, is a significant expansion of fungal protection. She co-founded **SPUN (the Society for the Protection of Underground Networks)** — a scientific organisation mapping fungal biodiversity globally and advocating for fungi to be included in conservation frameworks, climate agreements, and agricultural policy.
At the Tyler Prize ceremony, Kiers plans to launch the **Underground Advocates** programme — equipping scientists with legal and policy tools to protect fungal biodiversity in jurisdictions around the world, in the same way that conservation lawyers currently protect forests and wetlands.
**Why This Matters Right Now**
Climate policy is primarily focused on what happens above ground: trees, emissions from smokestacks and tailpipes, solar panels and wind turbines. The below-ground carbon cycle — the living soil, the fungi, the microbial communities that hold and process carbon — has been a blind spot.
If mycorrhizal networks are indeed sequestering one-third of fossil fuel emissions annually, then their destruction — through intensive agriculture, fungicide use, soil compaction, deforestation — is a climate problem of the first order. And their protection and restoration is a climate solution that costs relatively little and requires primarily awareness.
The world knows about trees. It is beginning to learn about fungi.
And the scientist who has done the most to make that possible just won the highest honour environmental science bestows.
The forest is deeper than we thought. The roots go further. And what connects them, in the dark, is working. 🍄
*Sources: Tyler Prize 2026 (tylerprize.org) · Vrije Universiteit Amsterdam (vu.nl) · Current Biology (2023) — global mycorrhizal carbon flux study · Society for the Protection of Underground Networks (spun.earth) · The Hindu · GK Today · The Microbiologist · Mongabay (2026)*
