By Abbas Nazil
Enhanced Rock Weathering (ERW) is emerging as a significant carbon removal method capable of capturing hundreds of millions of tonnes of carbon dioxide annually by mid-century.
ERW accelerates a natural geological process in which rocks, including basalt and silicates, react with CO₂ over thousands of years.
By crushing these rocks into fine powder and spreading them across soil, the surface area of the rocks increases, speeding up their reaction with carbon dioxide in the air and soil.
Scientists estimate that ERW could remove up to 350 million tonnes of CO₂ per year by 2050 if widely deployed across agricultural lands and other suitable areas.
The process works as rainwater dissolves atmospheric CO₂ into carbonic acid, which reacts with silicate rocks, locking carbon into bicarbonate ions.
Some of these ions are carried into rivers and eventually the oceans, where they can remain sequestered for thousands of years.
In agricultural applications, rock dust applied near plant roots enhances carbon capture while also improving soil nutrition and structure, potentially boosting crop yields and reducing fertilizer needs.
ERW is considered more permanent than some nature-based solutions because carbon is stored in stable minerals rather than temporarily in vegetation.
The method can also leverage existing mining and farming infrastructure, using known equipment for crushing and spreading rock, making it more scalable than energy-intensive approaches like direct air capture.
Early ERW carbon removal projects have begun issuing independently verified credits, with investment in the sector reaching approximately US$121 million and credit prices ranging from $200 to $500 per tonne.
Despite its potential, several challenges remain for ERW to reach its mid-century targets, including accurate monitoring, reporting, and verification of carbon removal, logistics for quarrying and spreading rock globally, and agronomic adoption by farmers.
Further studies are needed to assess long-term ecosystem impacts and optimal application rates for different soil types and crops.
Policy support, carbon markets, and incentive structures are seen as critical to scaling ERW.
As part of a broader carbon removal portfolio alongside reforestation, bioenergy with carbon capture, and direct air capture, ERW could play a major role in meeting global net-zero targets and limiting temperature rise under the Paris Agreement.
With rapid deployment and strong investment, ERW has the potential to make a substantial contribution to reducing atmospheric CO₂ by 2050.