In the past few years, enhanced rock weathering (ERW) as a carbon removal method evolved from a novel pathway into an investable, climate-oriented solution. The approach accelerates naturally occurring weathering by spreading CO2-reactive silicate rock dust on soils, and widely-cited estimates say it could remove up to 2–4 gigatons of carbon dioxide annually, depending on global deployment.
The momentum behind ERW is real: proponents are working hard on demonstrating its scalability and value for net zero goals, while buyers, including Microsoft, Boeing, and Stripe, among others, are betting on it for their sustainability strategies.
But this optimism is matched by caution from experts and scientists who point to unresolved questions around quantification, MRV, and field-level impacts. Even with the array of benefits it delivers, many still wonder if ERW can be considered a credible and reliable way to fight CO2 pollution at scale.
With approaching climate deadlines and a narrowing window for action, the debate around ERW may need to evolve from whether it works or not to a broader, more practical understanding that considers its potential, its limits, and the conditions required for it to become a credible climate asset.
ERW is not a simple yes-or-no question
In a conversation with Professor Noah Planavsky from the Department of Earth & Planetary Sciences at the Yale Faculty of Arts and Sciences, we talked about the current outlook on ERW and its potential future development.
Professor Planavsky says that when it comes to evaluating enhanced weathering, the focus could be placed on different aspects in the context of carbon markets, research and funding efforts, and carbon removal in general.
To him, good carbon removal has to be real; we have to be able to measure it, and it has to be durable. If, for example, there’s a high reversability risk in an ERW project in the long term, that’s going to be a problem for compensatory claims, but it doesn’t mean we shouldn’t still be focusing on that ERW project. Or if a project doesn’t provide any co-benefits, it shouldn’t be dismissed in these early stages and postponed for future consideration when it can still be helpful now.
In his opinion, to consider ERW in binary terms—as either working or not working—is a very flawed way to think about the problem.
Rather, Professor Planavsky says, we should be trying to think about where this process is going to be a really cost-effective climate solution and a cost-effective way to help farmers, who are some of the people most affected by climate change, working in a sector where margins are very difficult.
What is currently causing Enhanced Rock Weathering concerns?
ERW still carries uncertainties around how exactly it will be implemented, and relevant actors are continuously calling for stronger MRV systems to track how much CO2 exactly can be removed through it and how it impacts different soil environments.
The rate at which ERW can remove carbon from the atmosphere depends on the soil conditions, and this similarly also affects the co-benefits that can be delivered.
To help identify favorable climates and conditions, nonprofit organization Cascade Climate has created a digital tool that points to locations around the globe with suitable environments for ERW carbon removal.
While efforts like this one lay the groundwork for ERW scaling, there is a general sector consensus that this pathway needs further research and testing to determine ways in which to maximize both its CO2 removal impact and the co-benefits it delivers.
One of the publications highlighting this need is a 2025 study, which signals that different geochemical and mineralogical compositions of rock powders might lead to overestimated CDR rates in ERW.
The study outlines the common pitfalls in quantifying ERW carbon removal, noting that mineralogically complex rock powders might initially exhibit fast dissolution rates due to reactive surfaces and phases, leading to overestimating long-term CDR rates.
Additionally, the paper points out, quantification methods that rely on measuring cations may be prone to misinterpretation, as cations will often not be balanced with dissolved inorganic CO2, e.g., during strong acid weathering.
Relevant: The Carbon Drawdown Initiative Unlocks Testing Innovation For ERW Effectiveness
Commenting on this aspect of ERW, Professor Planavsky says, “When it comes to the hot topic of measurements, it’s not a question if we can measure what the carbon fluxes are; it’s just a question of how cost-effectively we can do it.”
In his professional experience at the Yale Geochemistry Center, there have been a lot of research trials with extensive monitoring that have a really good sense of what carbon fluxes are, yet those same measurements won’t be practical for commercial deployments or deployments at scale, whether funded through the government, subsidies, or carbon markets.
“We want to be able to know where this is most effective. But part of that is being able to increase our ability to make more measurements and gauge the effectiveness of this process in a way that is financially operable.”
Besides potential MRV shortcomings, another important consideration around ERW is the need for low-contaminant mineral sources, as pulverized rocks often contain heavy metals that can accumulate in the soil and have a negative effect on health, and this too will require testing and monitoring to ensure safety.
What have real-life Enhanced Rock Weathering deployments shown us so far?
The Enhanced Weathering Alliance, an initiative of the Carbon Business Council, has launched a map that shows the active ERW initiatives happening around the globe, showcasing a lively sector that’s gaining traction across the planet.
One of the companies actively working on advancing ERW is UNDO, who’s been named as one of the four global winners of the $100M XPRIZE Carbon Removal competition.
The company also has a longstanding cooperation with Microsoft, and in October 2025, the two partners signed their third ERW carbon removal deal, backed by a novel debt financing structure by the Inlandsis fund.
Talking to our team on the development of ERW so far, UNDO CEO and Founder Jim Mann echoes the words of Phil De Luna, whose piece in Forbes reflects on the Carbon Removal XPRIZE competition, calling its conclusion “one of the most quietly consequential forces shaping carbon removal in 2025.”
De Luna says, “The four-year competition wasn’t designed simply to crown a winner—it was meant to pull an entire category forward. And nowhere was that more evident than in enhanced rock weathering… By the time the competition concluded, ERW moved from speculative pathway to credible, investable option.”
Building from this, Mann points out that the buyer confidence in ERW as a science-backed pathway has also grown—a claim supported by the company’s third and largest contract inked with Microsoft.
Sharing about the lessons his company has learned from practical ERW operations so far, Mann states that scale comes from repetition, not novelty. “We reach real numbers by running the same playbook again and again,” he says.
“If you are a corporate buyer, a lender, or a policymaker, we have the same request: make projects bankable,” Mann adds. “Contract real demand, tighten MRV, and structure debt that fits how projects work on the ground. When results are repeatable, you can finance them.“
“Draw alongside fieldwork, repay on delivery, plan multi-year, and keep evidence and quality at the core. If you want scale, write multi-year master agreements with volume ramps and options so we can plan equipment, crews, and rock supply with confidence.”
Read more: UNDO Carbon: A Spotlight on Enhanced Weathering
Credible MRV Is Key For Enhanced Rock Weathering advancement
UNDO also specializes in one of the most sensitive spots of enhanced weathering—MRV systems. Mann explains that UNDO’s approach is built to generate robust, continuous MRV data across climates and seasons and support independent verification.
This advancement is also enabled by the company’s Sentinel Sites, which serve as “deep science” plots—small but meticulously designed experimental farms where cutting-edge techniques are used to collect comprehensive data across all phases of the weathering process: solid, aqueous, and gaseous.
By employing sophisticated tools such as isotopic tracing techniques and bioinformatics, UNDO monitors the relationships between all of the biogeochemical processes that drive weathering reactions.
“The key to robust MRV with ERW is to demonstrate alignment between cation and anion chemistry in solid and liquid phases across a spatial area and at different soil depths to give a true 3-dimensional understanding of what is happening at a system level,” Mann says. “Once this is achieved across a robust time series, we can have real confidence that ERW has robust MRV and is ready to scale.”
UNDO, together with scientists from the James Hutton Institute and other researchers, recently proposed a new method for monitoring carbon removal in ERW called SAT-C. This novel method builds on a 2025 study from Jones et al. at Imperial College that introduced centrifugation for ERW porewater extraction.
While many experts and scientists consider porewater extraction a direct route to measuring ERW carbon removal, this method can struggle to yield sufficient samples when soils are dry—a factor that creates seasonal gaps that may underestimate the total CDR achieved. With the SAT-C method, on the other hand, scientists take an intact core from the field, saturate it with deionized water in the lab, and then spin it in a centrifuge to extract the porewater.
Jim Mann shares that UNDO’s patent-pending measurement technique allows the company to achieve a high level of certainty. “I believe the fundamental MRV is now resolved, and ERW is set to grow rapidly over the coming years.”
Beyond the fundamental need of further ERW research, Mann also stresses the important role of financing that can provide the lever needed to unlock growth for this high-potential CDR pathway.
What should the next steps be for Enhanced Rock Weathering?
For ERW to move into its next stage, the sector will need to turn today’s momentum into repeatable, verifiable performance.
The publication of this article comes at a time when ERW fortification efforts are already underway. Just a few days before this release, Cascade Climate announced the launch of the Bedrock Initiative—a global coordinated research effort to generate and build up the scientific evidence needed for scaling enhanced rock weathering (ERW) to climate-relevant levels.
Enhanced rock weathering is currently sitting in a space that is both promising and demanding. It has the potential to deliver durable CO2 removal, supporting farmers and improving soil systems, but its credibility will depend on how well the sector answers the questions still surrounding MRV, ecosystem safety, and real-world performance.
Jim Mann adds, “While stronger standards, lower costs, more field data, and larger buyers all have their part to play, policy remains the critical unlock. Compliance carbon markets—not voluntary—will ultimately drive scale, unlock supply constraints, and move the entire industry forward.”
