The biotic enhancement of Ca-Mg silicate weathering has helped maintain Earth’s habitability over geological time scales by assisting in the gradual drawdown of atmospheric CO2. 25 years of in-situ measurements of Ca-Mg silicate mineral dissolution by ants, termites, root mats, bare ground, and a control reveals ants to be one of the most powerful biotic weathering agents yet recognized. Six sites in Arizona and Texas (USA) indicate that eight different ant species enhance mineral dissolution by ∼50×–300× over controls. A comparison of extracted soil at a 50 cm depth in ant colonies and adjacent bare ground shows a gradual accumulation of CaCO3 content for all eight ant species over 25 yr. Ants, thus, have potential to provide clues on how to enhance contemporary carbon sequestration efforts to transform Ca-Mg silicates and CO2 into carbonate. Given that ants underwent a great diversification and biomass expansion over the Cenozoic, a speculative implication of this research is that ant enhancement of Ca-Mg silicate dissolution might have been an influence on Cenozoic cooling.