Enhanced weathering

[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.

[8][9] In July 2020, a group of scientists assessed that the geo-engineering technique of enhanced rock weathering, i.e., spreading finely crushed basalt on fields – has potential use for carbon dioxide removal by nations, identifying costs, opportunities, and engineering challenges.

[10][11] Weathering is the natural process of rocks and minerals dissolving to the action of water, ice, acids, salts, plants, animals, and temperature changes.

Of course, these are reversible reactions, so if the carbonate encounters H ions from acids, such as in soils, they will react to form water and release CO2 back to the atmosphere.

Given that some of the dissolved cations react with existing alkalinity in the solution to form CO32− ions, the ratio is not exactly 1:1 in natural systems but is a function of temperature and CO2 partial pressure.

[clarification needed] Weathering and biological carbonate precipitation are thought to be only loosely coupled on short time periods (<1000 years).

[clarification needed] Enhanced weathering was initially used to refer specifically to the spreading of crushed silicate minerals on the land surface.

[16][17] Biological activity in soils has been shown to promote the dissolution of silicate minerals,[18] but there is still uncertainty surrounding how quickly this may happen.

Mixing the soil with crushed rock such as silicate benefits not only plants' health, but also carbon sequestration when calcium or magnesium are present.

[29] Remineralize The Earth is a non-profit organization that promotes rock dust applications as natural fertilizers in agriculture fields to restore soils with minerals, improve the quality of vegetation and increase carbon sequestration.

[32] UNDO, a UK-based Enhanced Weathering company, spreads crushed silicate rock, such as basalt and wollastonite, on agricultural land in the United Kingdom, Canada and Australia.

In March of 2024, they published a peer-reviewed paper[33] in partnership with Newcastle University in PLOS ONE journal concerning the agronomic co-benefits of crushed basalt in a temperate climate.

Claiming it improves soil quality and crop productivity, the company sells carbon removal credits to fund the costs.