Beneath every forest, meadow, and grassland on Earth, there is another world.
A vast, invisible network of fungal threads — mycorrhizal fungi — threads itself through the soil, connecting the root systems of plants, exchanging nutrients and water, carrying chemical signals, and doing something even more remarkable: storing carbon. Billions of tonnes of it, every year, quietly locked away underground.
Dr. Toby Kiers has spent her career studying this hidden world. And in 2026, she has been awarded the Tyler Prize for Environmental Achievement — sometimes called the Nobel Prize for the Environment — becoming the youngest woman ever to receive the honour.
Kiers is Professor of Evolutionary Biology at Vrije Universiteit Amsterdam. Her research has transformed our understanding of what mycorrhizal networks actually do. They aren't passive pipes. They're dynamic, adaptive systems — capable of something that looks, in a biological sense, remarkably like trade. Plants feed sugars to fungi in exchange for phosphorus and water. The terms of that exchange shift depending on supply and demand. Fungi that provide better service receive more carbon. Fungi that cheat get cut off.
The implications for the climate are profound. Kiers and her collaborators have calculated that plants divert approximately 13 billion tonnes of CO₂ equivalent per year into mycorrhizal fungi. That's more than the total annual emissions of the United States and the European Union combined, flowing underground into fungal networks that — if those networks are healthy — lock that carbon away from the atmosphere.
If those networks are disrupted — by industrial agriculture, soil compaction, fungicide use, or land conversion — that carbon storage capacity collapses. We may be inadvertently destroying one of the planet's most powerful carbon sinks, largely because it's underground and invisible.
Beyond her science, Kiers co-founded the Society for the Protection of Underground Networks (SPUN), a global initiative that has developed a high-resolution 'Underground Atlas' — the most detailed map ever created of mycorrhizal biodiversity. SPUN works to identify the most critical underground ecosystems globally and prioritise their protection.
She will receive the $250,000 Tyler Prize at a ceremony in Amsterdam on April 23, 2026.
The fungi beneath our feet have been quietly saving the planet for hundreds of millions of years. Dr. Kiers has spent her career making sure we finally understand that — before it's too late to protect what's down there. 🍄