Olivine Weathering against Climate Change

Abstract

One natural process has since the origin of the Earth removed almost all the CO 2 that was ever produced by volcanism. That process is the reaction of CO 2 and water with rocks, a process known as weathering. It is a logical choice to see if we can use the same process to remove also the vastly higher CO 2 emissions caused by burning in a few hundred years the fossil fuels that have taken hundreds of millions of years for their formation. Many people claim that the rate of weathering of olivine is too slow to counter climate change, but they base this on experimental data in sterile laboratories, under exclusion of biotic and other environmental factors. As many conditions determine the weathering rate at each specific location, these laboratory conditions are irrelevant for the real world. Weathering models based on these laboratory data are off by orders of magnitude. Weathering experiments that use conditions closer to nature [1] show already much higher weathering rates. In this note I provide some data on the weathering of olivine in nature, which make clear that the weathering of olivine is fast enough to play an important role in the cycle of CO 2 capture and its safe and sustainable storage as carbonate rocks. The CO 2 released by volcanism has always been captured by the weathering of rocks since the origin of the Earth. Without this mechanism the Earth would be a lifeless planet with a CO 2 atmosphere in the order of 100 bar, as our neighbor planet Venus demonstrates.