Olivine to Combat Climate Change

• Main Author: Schuiling, R.D.
• Format: Article
• Language: English
• Published: Інститут геохімії, мінералогії та рудоутворення ім. М.П. Семененка НАН України 2011
• Series: Мінералогічний журнал
• Subjects: Дискусії, критика, бібліографія
• Online Access: http://dspace.nbuv.gov.ua/handle/123456789/63455

Weathering of basic rocks, containing magnesium and calcium silicates, is the main mechanism to capture CO₂ in a sustainable way, with storage of organic carbon a distant second. The CO₂ emission by Man, due to the combustion of fossil fuels is at least ten times larger than the natural CO₂ emission from the Earth. Emission and capture are no longer in balance, and the concentration of CO₂ in the atmosphere is steeply rising. It is a logical step to investigate whether we can stimulate the natural process of weathering in such a way that the balance is restored. Weathering takes place at the surface of rocks, so we must increase the available surface area. This can be done by mining and milling suitable rocks, and spread the powder over land and in shallow seas. Factors that influence the rate of reaction, apart from grain size, are temperature, pH and water. This means that soils in tropical countries are best suited. Soil atmospheres are on average hundred times richer in CO₂ than air. This is caused by the decay of plant material and the respiration of soil fauna. A high CO₂- pressure causes a low pH, which is favorable for weathering. The most suitable rock type is dunite, which consists for more than 90 % of olivine. Dunite massifs are found in many countries on each continent. Large massifs occur among others in Guinea, Sierra Leone and Ivory Coast. By mining the olivine there, milling it and spreading a thin layer over the surroundings, climate change can be counteracted. Weathering is a natural process, that has kept the CO₂ level of the atmosphere within bounds for billions of years, thus no short term or long term negative ecological consequences are to be expected.