Enhanced weathering, also termed ocean alkalinity enhancement when proposed for carbon credit systems, is a process that aims to accelerate the natural weathering by spreading finely ground silicate rock, such as basalt, onto surfaces which speeds up chemical reactions between rocks, water, and air. It also removes carbon dioxide (CO2) from the atmosphere, permanently storing it in solid carbonate minerals or ocean alkalinity.[1] The latter also slows ocean acidification.
Enhanced weathering is a chemical approach to remove carbon dioxide involving land-based or ocean-based techniques. One example of a land-based enhanced weathering technique is in-situ carbonation of silicates. Ultramafic rock, for example, has the potential to store hundreds to thousands of years' worth of CO2 emissions, according to estimates.[2][3] Ocean-based techniques involve alkalinity enhancement, such as grinding, dispersing, and dissolving olivine, limestone, silicates, or calcium hydroxide to address ocean acidification and CO2 sequestration.[4]
Although existing mine tailings[5] or alkaline industrial silicate minerals (such as steel slags, construction & demolition waste, or ash from biomass incineration) may be used at first,[6] mining more basalt might eventually be required to limit climate change.[7]