Enhanced rock weathering shows little climate benefit in large trial

To fight climate change and achieve net-zero carbon emission targets, governments are increasingly betting on technologies that remove carbon dioxide from the air. One of the most prominent is enhanced rock weathering (ERW), which involves spreading finely ground rock onto land, often agricultural fields. Minerals in the rock slowly react with CO2 dissolved in rainwater, forming ions such as bicarbonate (HCO3-) that lock away the carbon.But the results of a 3-year field trial in Switzerland demonstrate that ERW is no panacea for climate change (Environ. Sci. Technol. 2025, DOI: 10.1021/acs.est.5c09820). The trial found relatively low rates of CO2 removal—less than 10% of the rates reported by some other studies (Sci. Total Environ. 2023, DOI: 10.1016/j.scitotenv.2023.166118). “This technology has been oversold as some sort of silver bullet against climate change,” says Xavier Marie Dupla, a soil geochemist at the Swiss Federal Institute of Technology (ETH), Zurich, who led the study. “Our paper is saying, This is not a magic instrument that is going to work everywhere.”“Nobody expects it to work everywhere,” counters David J. Beerling, director of the Leverhulme Centre for Climate Change Mitigation at the University of Sheffield, who is involved in several long-term ERW field trials and was not part of the Swiss study. “This is, in some ways, a classic demonstration of where it isn't going to work,” he says.ERW typically employs rocks rich in silicates that can help convert CO2 into bicarbonate. These bicarbonate ions are washed through soils and rivers into the ocean, where they can