How It Works

Quick Facts

Market Position

Largest deal to date: 290K tonnes by Terradot in 2024 (cdr.fyi)
Largest delivery to date: 3,814 t CO2 by Undo (cdr.fyi)
Total delivered volume: 5,680 t CO2 (cdr.fyi)

Carbon Removal Potential

2 to 4 gigatonnes of CO2 per year globally by 2050 (Fuss et al., 2018)

End uses

Primarily land-based: agricultural soils, marginal lands, and in some cases, coastal areas

Co-Benefits

Soil Health

Improves soil health by raising pH and adding micronutrients

Lime Replacement

Can replace agricultural lime with a lower environmental footprint  

Sustainable

Compatible with regenerative agriculture practices

The Science

Enhanced weathering is rooted in a well-understood natural process: the slow breakdown of minerals in rocks that naturally draws carbon dioxide out of the atmosphere. When it rains, silicate and carbonate rocks react with CO₂ from the atmosphere, forming bicarbonates that are stable over geological timescales.
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To accelerate this reaction, enhanced weathering uses finely ground rock materials—such as basalt, olivine, or industrial byproducts like steel slag or concrete. By increasing the surface area, the reaction happens faster and more efficiently when the material is applied to soils and exposed to rainfall.
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Once spread on land, the crushed rock interacts with CO₂ in the air and water to produce dissolved bicarbonate ions. These ions are slowly transported through soil and waterways into rivers and eventually into the ocean, where they are stored for thousands to tens of thousands of years.

Integration with Agriculture

Most enhanced weathering projects today are implemented on agricultural soils. Provided a good fit with the local ecosystems, the added rock dust can lead to a number of co-benefits:

Raises soil pH, counteracting soil acidity to improve conditions for plant growth
Releases beneficial nutrients like magnesium, calcium, and potassium into the soil
Improves crop resilience and yield
Reduces the need for conventional lime, which has a higher environmental footprint
Supports regenerative agriculture practices

Monitoring and Measurement

The carbon removal process from enhanced weathering is scientifically established, but quantification in field conditions is still being improved with a need for additional funding. Weathering rates vary depending on:

Soil composition and pH
Temperature and rainfall
Particle size and type of rock
Land management practices

Current measurement efforts focus on tracking soil carbon fluxes, bicarbonate accumulation, and chemical markers in soil and runoff. Multiple field trials across continents are refining these approaches. Entities like Cascade Climate are coordinating ambitious cross-sector initiatives to unlock cycles of learning-by-doing and resourcing high-leverage R&D and policy work.

Material Sourcing and Sustainability

To be viable at scale, enhanced weathering projects must rely on sustainable, low-impact sources of rock material. Most current projects use mining waste or locally available industrial residues, minimizing the environmental impact of extraction and transport.
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Because rocks are heavy and transportation is carbon-intensive, proximity to application sites is critical. Local supply chains and circular use of industrial byproducts offer scalable paths forward.

Environmental Risks and Considerations

While enhanced weathering offers a promising carbon removal pathway, full traceability, responsible sourcing, and diligent material testing is critical. Certain rock types may contain trace heavy metals that could accumulate in soils over time if not properly screened. Additionally, scaling up the material supply could increase pressure on natural landscapes if it leads to new quarry development. To mitigate these risks, projects must prioritize the use of tested, low-contaminant materials and emphasize circular solutions such as mining waste and industrial byproducts, while avoiding extraction in ecologically sensitive areas.