OLIVINE AND CLIMATE CHANGE

摘要

The greenhouse effect, thanks mainly to the water vapor in our atmosphere, has created a livable climate on Earth. Climate change, however, may potentially have dire consequences. It is generally assumed that the rise in CO2 levels in the atmosphere is the main culprit, although several other greenhouse gases (GHG) also play a role. Next to limitation of CO2 emissions by higher efficiency, developing alternative energy sources or changing our wasteful style of living, there are two general approaches to combat climate change. Both fall under the heading 'Geo-engineering the Climate', a report submitted to the Royal Society in 2009. These include methods to fight: 1. symptoms, or 2. causes. The first group encompasses attempts to change the Earth's albedo, for example by spreading aerosols of SO2 in the stratosphere, or painting all our roofs white. Among methods to remove CO2 from the atmosphere, the best known are CCS (carbon capture and storage) and 'geological storage', which has nothing to do with geology, except for the receptacle being of natural origin [1]. There are two processes by which CO2 has been removed from the atmosphere throughout geological time, primarily by weathering reactions of Ca- and Mg-silicates, and to a lesser extent by storage of organic carbon in coal beds, oil and natural gas, anci carbonates. Thus, enhanced weathering is a logical step to remove CO2 from the atmosphere. To that purpose, abundant rock types available in large volumes are ground to increase reactivity, possibly mix with pyrolized wood known as 'biochar' (Brazil: 'terra preta'), and spread the mix in climate zones that favor rapid weathering, that is the wet tropics. Industrializing nations like India, China or Brazil would not need to limit their CO2 emissions by restricting industrial production, and thereby slowing their economic development, but could instead compensate their emissions by enhanced weathering.