Enhanced weathering with agriculture for atmospheric carbon dioxide removal

17 - 18 November 2025 09:00 - 17:00 The Royal Society Free Watch online
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Enhanced weathering header

Discussion meeting organised by Professor David Beerling FRS, Professor Rachael James, Dr Noah Planavsky and Dr Christopher Reinhard

This meeting will discuss advances and uncertainties in terrestrial enhanced weathering, a key carbon dioxide removal strategy for climate change mitigation. Recent discoveries and R&D investment are accelerating the prospect of large-scale EW implementation, but uncertainties remain. The goal of this meeting is to provide a much-needed balanced discussion on the scientific and societal challenges ahead.

Programme

The programme, including speaker biographies and abstracts, will be available soon. Please note the programme may be subject to change.

Poster session

There will be a poster session from 17:00 on Monday 17 November 2025. If you would like to present a poster, please submit your proposed title, abstract (up to 200 words), author list, and the name of the proposed presenter and institution no later than 19 October 2025.

Attending the event

This event is intended for researchers in relevant fields.

  • Free to attend
  • Both virtual and in-person attendance is available. Advance registration is essential. Please register via Eventbrite for a ticket
  • Lunch is available on both days of the meeting for an optional £25 per day. There are plenty of places to eat nearby if you would prefer purchase food offsite. Participants are welcome to bring their own lunch to the meeting

Enquiries: Scientific Programmes team.

Image credit: ©️David Beerling

Schedule

Chair

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Professor David Beerling, University of Sheffield, UK

09:00-09:05 Welcome by the Royal Society and lead organiser
09:05-09:30 Talk title TBC
09:30-09:45 Discussion
09:45-10:15 Enhanced rock weathering drives soil carbon sequestration and nutrient cycling: Evidence from Chinese plantations and global meta-analysis

Enhanced rock weathering (ERW) is a promising carbon dioxide removal (CDR) strategy for soil carbon sequestration and climate mitigation. This study integrates a 2-year field monitoring in Chinese tropical rubber plantations and global meta-analysis to examine ERW via crushed rock amendments on soil carbon dynamics and ecosystem functions. Field study show ERW increased soil organic carbon (SOC) and mineral-associated organic carbon (MAOC) in tropical regions, elevated carbon-fixation genes while reducing carbon-degradation genes in soil microbes (enhancing SOC retention), and improved nitrogen cycling, root phosphorus acquisition, and ecosystem multifunctionality. Furthermore, a global meta-analysis of 74 studies indicates crushed rocks increased SOC (3.8%), MAOC (6.1%), and particulate organic carbon (7.5%) on average, with no impact on other fractions. SOC accrual was driven by exchangeable calcium, microbial biomass, and soil structure, co-controlled by local climate. Machine learning simulations of global croplands reveal strong site-dependency in ERW’s SOC effects: positive in low-latitude regions (40°N-40°S) but negative in high-latitude areas. Models also indicate an optimal ERW application range of 50-500 g m-1 for maximizing SOC sequestration, beyond which positive effects diminish and negative ones intensify. This empirical synthesis supports ERW, particularly with Ca-rich amendments, is an effective strategy for CDR by enhancing SOC stabilization and long-term CO2 sequestration via mineral-organic interactions and indirectly driving biological carbon sequestration process. Maximizing ERW’s positive CDR effects requires comprehensive consideration of site-specific climatic and soil characteristics, alongside appropriate application rates and durations.

Dr Tongtong Xu

Dr Tongtong Xu

Northwestern Polytechnical University, China

10:15-10:30 Discussion
10:30-11:00 Break
11:00-11:30 EW and rice agriculture in India
Mr Shantanu Agarwal

Mr Shantanu Agarwal

Mati Carbon PBC, US

11:30-11:45 Discussion
11:45-12:15 Organic carbon cycle feedbacks determine the climate mitigation potential of enhanced rock weathering in a forestry context

Enhanced rock weathering (ERW) for climate change mitigation is usually considered in the context of croplands. Yet rock dust can also be deployed to intensively managed (i.e. planted) forests. These forests now occupy 300 million hectares and frequently have appropriate infrastructure for rock dust deployment; they also occur in climatic zones that are favourable for rock weathering. A key question is whether the presence of trees (as opposed to crops) accelerates the weathering process, and whether long-lived vegetation serves as a sink for weathering products. To address this knowledge gap, we conducted a large-scale (12 ha) ERW trial in a newly planted forest. The ERW treatment was crossed in a fully factorial design with the addition of a forest soil inoculum, intended to re-establish populations of beneficial microbes which were presumably lost during the site’s multi-century prior use as a sheep pasture. We found that although rock dissolution proceeded relatively rapidly, most of the weathering products were either sorbed to soil exchange sites or taken up by plants, resulting in a significant increase in carbon sequestration into wood. Application of rock dust also enhanced soil respiration; as a result, more soil carbon was released to the atmosphere than was captured via weathering. Unexpectedly, introducing forest soil microbes to the site significantly slowed rock dissolution. Thus, plant and microbial responses determined both the sign and magnitude of weathering-related carbon dioxide fluxes five years after the first rock dust application.

Dr Bonnie Waring

Dr Bonnie Waring

Imperial College London, UK

12:15-12:30 Discussion

Chair

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Dr Chris Reinhard

Georgia Institute of Technology, US

13:30-14:00 EW and Brazilian agriculture

Terradot is leading science-based farm trials to evaluate the agronomic benefits of basalt rock dust application across diverse farming systems in Brazil. This work supports the scaling of Enhanced Rock Weathering (ERW) as a carbon dioxide removal (CDR) strategy, while also delivering improvements in soil health and crop yields for farmers. Brazil’s diverse climates, soil types, and cropping systems provide an ideal environment for assessing the potential of basalt to enhance soil fertility and agricultural productivity.

Field trials are being conducted across multiple partner farms to evaluate the effects of basalt on key agronomic indicators, including soil pH, base saturation, nutrient availability, and crop yield. These trials span a variety of environmental conditions and were designed to generate field-specific insights into how local factors—such as precipitation, elevation, and soil texture—influence basalt dissolution and its agronomic performance. Particular attention is being given to the spatial and temporal variability of soil indicators across different soil textures.

Preliminary data from selected farms will be presented, including comparisons between basalt-treated and untreated control fields. While detailed results are still being collected and analysed, the presentation will highlight emerging trends and outline the methodological framework used to assess agronomic outcomes and co-benefits.

This work contributes to the expanding body of evidence supporting ERW’s dual role in carbon removal and agricultural enhancement, and lays the foundation for scaling rock dust applications tailored to the Brazilian agricultural landscape.

Dr Jonathan Ojeda

Dr Jonathan Ojeda

Terradot, Argentina

14:00-14:15 Discussion
14:15-14:45 River catchments as natural monitors of Enhanced Weathering: evidence from the Mississippi River

Accurately quantifying carbon dioxide removal (CDR) is critical for scaling enhanced weathering (EW) as a climate solution. River catchments serve as natural integrators for monitoring EW impacts at scale, capturing both spatially distributed application and downstream transport of weathering products. Using a large USGS dataset of US river chemistry, we simulate the silicate rock applications rates needed to observe a two SD signal above baseline. We find that EW signals are more likely to emerge in larger catchments with a high proportion of agricultural area, demonstrating the potential of this approach to monitor CDR from EW at scale.

We use carbonate addition to the Mississippi River Basin—one of the largest agricultural catchments globally—as a case study and historical analog for EW. Compiling over a century of agricultural, chemical, and hydrological data, we show that ~75% of lime added to soils has been exported as alkalinity, indicating that liming has acted as a net CO₂ sink. This challenges current greenhouse gas accounting frameworks, such as those of the IPCC, which treat liming as a CO₂ source and rather suggests that carbonate-rock-based EW can be an efficient path to achieving CDR. Attributing emissions to acidity addition instead enables a more geochemically accurate and policy-relevant understanding of CO2 emissions. Moreover, we find that acid-base reactions in soils may contribute more to agricultural CO2 emissions than currently recognized. These findings highlight the utility of riverine fluxes as a robust, scalable proxy for EW-based CDR and call for a revision of agricultural carbon accounting protocols.

Dr Tim Jesper Suhrhoff

Dr Tim Jesper Suhrhoff

Yale Center for Natural Carbon Capture, US

14:45-15:00 Discussion
15:00-15:30 Break
15:30-16:00 EW and net zero chocolate
Miss Issi Steeley

Miss Issi Steeley

Leverhulme Centre for Climate Change Mitigation, UK

16:00-16:15 Discussion
16:15-16:45 Effects of enhanced weathering on fundamental soil properties

Enhanced weathering (EW) is an intuitively attractive carbon dioxide removal strategy that involves the application of highly weatherable silicate rock powder (usually basalt) to soils to accelerate natural chemical weathering. While primarily developed for its potential in mitigating climate change by capturing atmospheric CO2, EW also has the potential to fundamentally alter soil biogeochemistry and pedogenesis. In this talk, we outline mechanisms through which EW may impact soil properties and functions. Using recent results from an EW field trial initiated in 2020 in vineyard of western Switzerland, we explore the effect of a single twenty ton per hectare basalt powder application on soil physical, mineralogical, chemical, and biological properties. Findings show that the basalt application stimulated soil biological activity and led to the formation of poorly crystalline secondary aluminosilicates and oxides. Altogether, these results indicate that soil-forming processes are significantly modified by the basalt powder addition. While the increase in biogeochemical reactivity of basalt-amended soils could be beneficial in many cases, many unknowns remain regarding the long-term sustainability of the practice. Overall, the integration of EW into sustainable agricultural practices may present a promising avenue for improving soil fertility in some agroecosystems, but could also pose significant risks for some soils and climate zones. Investment in long-term field studies is necessary to provide a full understanding of environmental consequences of EW and optimize implementation strategies.

Dr Stephanie Grand

Dr Stephanie Grand

University of Lausanne, Switzerland

16:45-17:00 Discussion
17:00-18:15 Poster session

Chair

Professor Rachael James

Professor Rachael James

University of Southampton, UK

09:00-09:30 Role of models in tracking carbon removal by EW
Dr Chris Reinhard

Dr Chris Reinhard

Georgia Institute of Technology, US

09:30-09:45 Discussion
09:45-10:15 Rivers, EW and C-cycling
Dr Pete Raymond

Dr Pete Raymond

Yale University, US

10:15-10:30 Discussion
10:30-11:00 Break
11:00-11:30 EW soil processes
Professor Isabel Montanez NAS

Professor Isabel Montanez NAS

University of California, Davis, US

11:30-11:45 Discussion
11:45-12:15 Atmospheric carbon dioxide removal via mineral-based ocean alkalinization

Conventional mitigation measures alone will be insufficient to limit global warming below 2°C, necessitating gigaton-scale atmospheric carbon dioxide removal (CDR). Oceans play a critical role in the global carbon cycle, absorbing 25 to 30% of anthropogenic CO2 emissions. The chemical weathering of carbonate and silicate rocks significantly contributes to atmospheric CO2 drawdown over geological time scales. Mineral-based ocean alkalinity enhancement (OAE) is a CDR technique that seeks to accelerate this natural process by distributing finely ground reactive minerals (e.g. olivine, lime) into suitable coastal and shelf environments. Laboratory experiments have demonstrated the potential of some silicate minerals, such as basalt and olivine, to be used as source material. In a similar fashion, some waste streams of the current mining industry have been examined for their potential. It remains to be tested, however, whether the dissolution rates obtained in these controlled experiments can be translated to the real world. In recent years, a number of dedicated mesocosm experiments and restricted field trials have been conducted to assess the sequestration potential and technology feasibility of mineral-based ocean alkalinity enhancement under more realistic, natural conditions. This presentation will provide an overview of the current state of knowledge.

Professor Filip Meysman

Professor Filip Meysman

University of Antwerp, Belgium

12:15-12:30 Discussion

Chair

Dr Noah Planavsky, Yale University, USA

13:30-14:00 Public acceptability of enhanced weathering in the global north and global south

In order to conduct responsible research and innovation well-engaged and informed communities must be embedded within the research process contributing to the decisions made about carbon dioxide removal approaches to tackle climate change. Using mixed methods we extensively explored how publics perceive enhanced weathering in the UK, US, Australia and Malaysia including nationally representative surveys (UK, US and Australia) alongside deliberative workshops in the UK, US and Malaysia. Findings illustrated that enhanced weathering was an unfamiliar strategy and produced a range of common concerns in all participants. Some of the environmental and social impacts included those on the marine environment, human health, and concerns regarding mining (particularly within Malaysia). The dependency of smallholders’ livelihoods on agriculture also resulted in questions about long-term impacts on crops and soils. In the Malaysian groups the economy was a prevalent topic, especially for more rural participants, with interest in how the strategy could be financially beneficial to smallholders including possible co-benefits on their crops. Overall our research shows participatory processes can and should be used to ensure socially responsible upscaling of enhanced weathering with our participants producing meaningful insights and directions for future research. However public acceptance will be dependent on meaningful deep emissions reductions being made, having suitable governance in place and serious consideration of appropriate economic and social costs if enhanced weathering is to be utilised.

Dr Elspeth Spence

Dr Elspeth Spence

Cardiff University, UK

14:00-14:15 Discussion
14:15-14:45 US & EU policies relevant to incentivising EW
Ms Anu Khan

Ms Anu Khan

Carbon Removal Standards Initiative, US

14:45-15:00 Discussion
15:00-15:30 Break
15:30-16:00 Panel discussion I: Engaging local communities
Dr Livia Fritz

Dr Livia Fritz

Aarhus University, Denmark

Professor Nick Pidgeon

Professor Nick Pidgeon

Cardiff University, UK

Professor Susan Owens OBE FBA

Professor Susan Owens OBE FBA

University of Cambridge, UK

16:00-16:15 Discussion
16:15-17:00 Panel discussion II: EW-MRV: future opportunities
Professor Rachael James

Professor Rachael James

University of Southampton, UK

Dr Matthew Clarkson

Dr Matthew Clarkson

InPlanet GmbH, UK

Dr Zeke Hausfather

Dr Zeke Hausfather

Stripe, Inc., US

Dr Noah Planavsky, Yale University, USA

Dr Noah Planavsky, Yale University, USA