carbon capture

the-world’s-largest-fungus-collection-may-unlock-the-mysteries-of-carbon-capture

The world’s largest fungus collection may unlock the mysteries of carbon capture

carbon capture, fungi, Science, syndication / /
Fungus samples are seen on display inside the Fungarium at the Royal Botanic Gardens in Kew, west London in 2023. The Fungarium was founded in 1879 and holds an estimated 380,000 specimens from the UK.

Enlarge / Fungus samples are seen on display inside the Fungarium at the Royal Botanic Gardens in Kew, west London in 2023. The Fungarium was founded in 1879 and holds an estimated 380,000 specimens from the UK.

It’s hard to miss the headliners at Kew Gardens. The botanical collection in London is home to towering redwoods and giant Amazonian water lilies capable of holding up a small child. Each spring, its huge greenhouses pop with the Technicolor displays of multiple orchid species.

But for the really good stuff at Kew, you have to look below the ground. Tucked underneath a laboratory at the garden’s eastern edge is the fungarium: the largest collection of fungi anywhere in the world. Nestled inside a series of green cardboard boxes are some 1.3 million specimens of fruiting bodies—the parts of the fungi that appear above ground and release spores.

“This is basically a library of fungi,” says Lee Davies, curator of the Kew fungarium. “What this allows us to do is to come up with a reference of fungal biodiversity—what fungi are out there in the world, where you can find them.” Archivists—wearing mushroom hats for some reason—float between the shelves, busily digitizing the vast archive, which includes around half of all the species known to science.

Fungarium Collections Manager Lee Davies inspects a fungus sample stored within the Fungarium at the Royal Botanic Gardens in Kew, west London in 2023.

Enlarge / Fungarium Collections Manager Lee Davies inspects a fungus sample stored within the Fungarium at the Royal Botanic Gardens in Kew, west London in 2023.

In the hierarchy of environmental causes, fungi have traditionally ranked somewhere close to the bottom, Davies says. He himself was brought to the fungarium against his will. Davies was working with tropical plants when a staffing reshuffle brought him to the temperature-controlled environs of the fungarium. “They moved me here in 2014, and it’s amazing. Best thing ever, I love it. It’s been a total conversion.”

Davies’ own epiphany echoes a wider awakening of appreciation for these overlooked organisms. In 2020, mycologist Merlin Sheldrake’s book Entangled Life: How Fungi Make Our Worlds, Change Our Minds, and Shape Our Futures was a surprise bestseller. In the video game and HBO series The Last of Us, it’s a fictional brain-eating fungus from the genus Cordyceps that sends the world into an apocalyptic spiral. (The Kew collection includes a tarantula infected with Cordyceps—fungal tendrils reach out from the soft gaps between the dead insect’s limbs.)

While the wider world is waking up to these fascinating organisms, scientists are getting to grips with the crucial role they play in ecosystems. In a laboratory just above the Kew fungarium, mycologist Laura Martinez-Suz studies how fungi help sequester carbon in the soil, and why some places seem much better at storing soil carbon than others.

Soil is a huge reservoir of carbon. There are around 1.5 trillion tons of organic carbon stored in soils across the world—about twice the amount of carbon in the atmosphere. Scientists used to think that most of this carbon entered the soil when dead leaves and plant matter decomposed, but it’s now becoming clear that plant roots and fungi networks are a critical part of this process. One study of forested islands in Sweden found that the majority of carbon in the forest soil actually came from root-fungi networks, not plant matter fallen from above the ground.

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The quest to turn basalt dust into a viable climate solution

carbon capture, climate adaptation, climate adaptation strategies, Science, syndication / /
The quest to turn basalt dust into a viable climate solution

Mary Yap has spent the last year and a half trying to get farmers to fall in love with basalt. The volcanic rock is chock full of nutrients, captured as its crystal structure forms from cooling magma, and can make soil less acidic. In that way it’s like limestone, which farmers often use to improve their soil. It’s a little more finicky to apply, and certainly less familiar. But basalt also comes with an important side benefit: It can naturally capture carbon from the atmosphere.

Yap’s pitch is part of a decades-long effort to scale up that natural weathering process and prove that it can lock carbon away for long enough to make a different to the climate. “The bottleneck is getting farmers to want to do this,” Yap says.

On Thursday, Yap’s young startup, Lithos Carbon, got a $57.1 million boost for its quest to turn basalt dust into a viable climate solution. It came from Frontier, a benefit corporation backed by a consortium of companies aiming to finance promising approaches to carbon dioxide removal, or CDR. Lithos says it will use the funds to soak up 154,000 tons of CO2 by 2028, by sprinkling basalt dust on thousands of acres of US farmland. The average US car emits about 4 tons of CO2 each year.

The carbon removal purchase is the largest yet by Frontier, which was formed last year with nearly $1 billion from its tech-dominated members. Many of those companies, which include Meta, Alphabet, and payments processor Stripe, which owns Frontier, have made climate pledges that require not only reducing the emissions from their operations and supply chains but also “negative emissions”—sucking up carbon from the atmosphere to cancel out other emissions.

That accounting trick has been easier to prove out on paper than in practice. Many companies would have once turned to buying carbon offsets from activities like protecting forests that would otherwise be felled. But some have been trying to move away from those scandal-plagued and often short-lived approaches and into more durable techniques for carbon removal.

The current options for companies seeking negative emissions are limited. Frontier’s purchases are essentially down payments on ideas that are still in their infancy—generally too hard to verify or too expensive, or both, to attract a significant customer base. “What we’re trying to evaluate the field on is whether it’s on the trajectory to get to climate-relevant scale,” says Nan Ransohoff, who leads Frontier and also climate work at Stripe. The group starts with small “prepurchases” meant to help promising startups, and then moves on to “offtake” agreements for larger amounts of carbon that its members can count toward their emissions goals.

The Lithos purchase is one of those larger deals. It prices carbon removals at $370 per ton, about a quarter of which will pay for field monitoring and modeling to verify that carbon is being sequestered away from the atmosphere for the long term. Ransohoff says Frontier believes that Lithos is on a path to its goal of removing CO2 for customers at a cost of less than $100 per ton, and at a rate of at least a half a billion tons per year.

“Most promising” approach

Lithos, founded in 2022, is developing a technology called enhanced rock weathering. It involves spreading a fine dust of basalt across fields before planting. As the rock further weathers from rainfall, it reacts with CO2 in the air. That forms bicarbonate, which locks away the carbon by combining it with hydrogen and oxygen atoms. Ultimately, the compound is washed into the ocean, where the carbon should stay put.

The strategy has the benefit of piggybacking on things that humans already do, Yap says. That’s in contrast with techniques like direct air capture, which involves building industrial plants that suck carbon out of the atmosphere. It’s easy to measure carbon removed that way—it’s all captured there onsite—but critics say it will be difficult to scale up because removing enough carbon to make a difference will require thousands of dedicate, resource-intensive facilities.

Using basalt dust to capture carbon should be more easily scaled up. There are plenty of fields to dump rock dust onto, and plenty of water for carbon to end up in. But the distributed nature of the process also makes measuring how much carbon was actually removed from the atmosphere more difficult.

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