Sustaining Life:The gigaton gambit
The ambitious Greenhouse Gas Removal project is underway. Here’s a look at four innovative ideas that aim to clean our atmosphere.
Story tags:
)
)
Illustrations by Joka Z.
The looming consequences of a rapidly warming planet are plainly dire: more deadly heat waves, mass extinction events, disruptions to food systems, and increased deforestation in the Amazon, to name a few. Reducing greenhouse gases might be the most urgent challenge facing humanity.
Stanford’s Sustainability Accelerator is taking on the challenge through its Greenhouse Gas Removal (GHG-R) projects. By supporting innovative, high-risk, potentially high-reward research, the initiative aims to enable removal of billions of tons of carbon dioxide annually from the atmosphere by 2050. It is the first of several so-called flagship destinations the accelerator will pursue in years to come.
In 2024, the Stanford Doerr School of Sustainability selected 16 research projects to begin this undertaking. No single one of these efforts will stabilize Earth’s climate, but together the hope is to have a meaningful impact. A common refrain in climate research, generally attributed to Bill McKibben: There’s no silver bullet, only silver buckshot.
Here’s a look at four of the projects that are currently being evaluated for their impact at scale.
)
We need to be able to measure carbon in soil in order to store it—but today’s soil monitoring tools are costly. A cheaper sensor could be a game changer. Illustration by Joka Z.
Building a better soil sensor
The emerging practice of paying farmers, ranchers, and other land managers to help capture carbon will need widespread and reliable monitoring. The technology for measuring the carbon from concentrated sources like smokestacks is well-established, but tracking the carbon absorbed by different landscapes—farms, grasslands, peatlands, newly restored ecosystems—is still in its infancy. Making the process easier and more affordable will be essential in the years ahead. Alison Hoyt, an assistant professor of Earth System Science, and her PhD student Jack Lamb, have already begun.
In order to measure carbon emissions at the landscape level, Hoyt had long lugged around a $40,000 trace gas analyzer. It weighed about 30 pounds, as did the battery pack that powered it for an hour. It was like being a band roadie, if the venue you were playing was in the middle of the Alaskan permafrost.
Given the mounting need for carbon sequestration verification, Hoyt and her team began pondering alternatives.
“We wanted something cheap and automated, because all of our expensive equipment is dying when we take it to these harsh places,” she says.
Hoyt started working on prototypes along with Maher, Debbie Senesky, who’s an associate professor of electrical engineering, and several students. The team came up with a model the size and shape of a small mixing bowl that costs less than $100, uses repurposed industrial sensors, and operates autonomously for a month on AA batteries.
Their prototypes were deployed in Alaska to test their hardiness in rugged environments; the next round will be tested in farms across California. Meanwhile, the team is refining the design with professional engineering and design firms, in preparation for scaling up production.
)
The measurements from this device might not be the most precise available, but the scale at which they could be adopted will enable entirely new types of research—similar to what’s happened in the last two decades with air sensors.
“We aspire to be like Purple Air one day,” Hoyt says of the air quality data firm. “Low-cost automated sensors, deployed all over.”
)
Small tree farmers are being left out of the carbon credit market. A new verification system could make reforestation efforts more accessible and equitable. Illustration by Joka Z.
Building better tree monitors
The growth of the carbon offsets market in recent years has raised new technical questions—when farmers are paid to plant new trees, for example, how shall those trees be counted and verified? And if this business is to be an enduring component of our atmosphere-scrubbing efforts, can it be arranged fairly?
The accounting process in this mini industry—how many trees were planted and how much carbon are they sequestering?—is now well established, says David Lobell, the Benjamin M. Page Professor of Earth System Science in the Stanford Doerr School of Sustainability and director of the Lobell Lab. But the farms that have historically been verified by global carbon markets tend to be the big guys—large plantations with thousands of acres. Smaller farms often must spend more money verifying that they’re actually planting trees—more money, they fear, than they’ll earn selling carbon credits based on that tree planting.
)
Lobell has a plan to bring those same incentives to farmers with as little as an acre. By using satellite imagery, he hopes to develop a verification process that doesn’t rely on onerous tree-by-tree measuring on the ground. The team is currently testing its data. Next it will assess the impact of these efforts on the landscape, as well as potential effects beyond carbon storage.
““There’s no silver bullet, only silver buckshot.”A common refrain in climate research, generally attributed to Bill McKibben
“Any carbon removal technology is much more likely to work when it has other benefits associated with it,” Lobell says. Trees offer many, he adds—erosion control, wildlife habitat, additional food sources, and refuge during heat waves. By lowering the barriers for more farmers to get paid, Lobell’s plan could allow for more trees, and more of the added benefits they bring.
)
Rocks naturally absorb carbon, but the process is slow. Scientists have found a way to speed it up. Illustration by Joka Z.
Building a better rock
Many rocks naturally dissolve upon contact with water and CO2 from the atmosphere, trapping carbon that eventually finds its way to the ocean; there it remains stable for thousands of years. This “rock weathering” process is slow, but integrated over the Earth’s surface it contributes about half a billion tons of carbon dioxide removal per year. By comparison, nearly 40 billion tons are emitted by fossil fuel combustion.
For decades, researchers have tried to achieve “enhanced rock weathering” by grinding up rocks and spreading them over large fields. These efforts have yielded very modest results to date, a testament to the stubborn sluggishness of the weathering process.
)
A team led by Matthew Kanan, professor of chemistry and director of the TomKat Center for Sustainable Energy, is working to scale up the deployment of a recently discovered thermal reaction between magnesium-rich silicate minerals (which are found in common rocks and in mining waste) and calcium minerals. The reaction dramatically increases both the amount of carbon sequestered by the rock and the speed with which it happens.
“There are minerals that remove CO2 fast enough to be used in the field, but they are naturally scarce,” says Kanan. “We found a way to take the abundant—but slow-weathering—minerals and convert them into these fast-weathering minerals. Its enhanced rock weathering by making better rocks.”
)
Laboratory and greenhouse studies have proven the concept, but field tests are just beginning. If modifying rocks this way is proven to reliably capture carbon in the field, the infrastructure already exists to produce and distribute it—mines and quarries already process rock onsite. The silicon in the rock produced by the Kanan Lab’s technique also has the added benefit of boosting harvests for some crops, and it might also help reduce fertilizer use.
)
Kelp could help capture carbon, but its potential impact is still unclear. A research project in Santa Barbara, California, hopes to change that. Illustration by Joka Z.
Building better seaweed farms
Seaweed has many potential uses in the fight against climate change, whether it’s for biofuels (unlike corn, it doesn’t require fresh water, fertilizer, or land), climate adaptation (it lowers the pH level of the water around it, mitigating ocean acidification), or for cleaning up the water (it also absorbs nitrogen that makes its way from farms out into coastal zones).
Then there’s carbon sequestration. “Macrocystis pyrifera, the giant kelp that grows off of California, can grow two feet a day in spring,” says Kristen Davis, an associate professor of oceans. “So they are really packing on the carbon. But if we want to understand how much is sequestered, we have to track this carbon through the full lifecycle of the kelp.”
)
While growing more kelp might sound like a good thing, kelp farming has many unknowns—like how it might affect offshore ecosystems. But through the use of models, Davis says, we can begin to predict the potential benefits or impacts without putting ocean wildlife at risk.
Davis is currently collecting data from a kelp farm in Santa Barbara, California, where she is observing ocean conditions and collecting data on seaweed biomass, nutrients, and carbon uptake. By gathering this information over the course of a growing season, she hopes to develop the kind of carbon accounting that can help assess the viability of kelp farming for greenhouse gas removal.
“There's a big question mark about seaweed as a solution to climate change right now,” Davis says. “We are doing the science to help address that question mark, and that's really exciting.”
David Lobell is also the Gloria and Richard Kushel Director of the Center on Food Security and the Environment, the William Wrigley Senior Fellow at the Stanford Woods Institute for the Environment and the Freeman Spogli Institute for International Studies, and a senior fellow at the Stanford Institute for Economic Policy Research.
Stanford Doerr School of Sustainability: The impact
Why it matters
Going slow is no longer an option. To meaningfully tackle the planet’s most urgent crisis—one that threatens both human and natural systems—we need big ideas and a big engine behind them. The Sustainability Accelerator at the Stanford Doerr School of Sustainability was created to speed the translation of Stanford research into scalable solutions, and to identify finance and policy pathways for those solutions to have maximum impact.
The opportunity
Even if emissions rapidly decline, strategies for removing greenhouse gases from the atmosphere will be essential for limiting global warming to below 2 C above pre-industrial levels, the ambition of the Paris climate agreement. The Sustainability Accelerator has funded 16 projects as part of its Greenhouse Gas Removal Flagship Destination, which aims to enable removal of gigatons of greenhouse gases per year from the atmosphere by 2050. No single project will alter our course. But together, they could have a substantial impact on the planet’s future.
)
:focal(2849x1496:2850x1497))
:focal(476x541:477x542))