Silicate Weathering

Study finds natural basalt weathering removes less CO2 than assumed

Researchers compiled river chemistry data from basaltic watersheds worldwide to recalculate how much carbon dioxide is naturally absorbed through silicate rock weathering. They found that critical zone processes—such as atmospheric deposition, hydrothermal contamination and secondary mineral formation—reduce the alkalinity that actually reaches rivers, meaning basalt weathering contributes a smaller share of global CO2 drawdown than prior estimates suggested, roughly 0.3% of annual anthropogenic emissions.