Before fossil fuels, Earth's minerals kept CO2 in check

Over millions of years carbon dioxide levels in the atmosphere have been moderated by a finely-tuned natural feedback system— a system that human emissions have recently overwhelmed. A joint University of Hawaii / Carnegie Institution study published in the advance online edition of Nature Geoscience links the pre-human stability to connections between carbon dioxide in the atmosphere and the breakdown of minerals in the Earth’s crust. While the process occurs far too slowly to have halted the historical buildup of carbon dioxide from human sources, the finding gives scientists new insights into the complexities of the carbon cycle.