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

“The system is finely in tune,” says Caldeira. “That one or two percent imbalance works out to an average imbalance in natural carbon dioxide emissions that is thousands of times smaller than our current emissions from industry and the destruction of forests.”

Previous researchers had suggested that such a system existed, but Caldeira and Zeebe’s study provides the first observational evidence supporting the theory, and confirms its role in stabilizing the carbon cycle. But because it operates over such a long time scale—the time scale over which landscapes are eroded and washed to the sea—this geological feedback system offers little comfort with respect to the current climate crisis.

Carbon dioxide is added naturally to the atmosphere and oceans from volcanoes and hydrothermal vents at a rate of about 0.1 billion tons of carbon each year. Human industrial activity and destruction of forests is adding carbon about 100 times faster, approximately 10 billion tons of carbon each year.

“The imbalance in the carbon cycle that we are creating with our emissions is huge compared to the kinds of imbalances seen over the time of the glacial ice core records,” says Caldeira. “We are emitting CO₂ far too fast to expect mother nature to mop up our mess anytime soon. Continued burning of coal, oil and gas will result in long-term changes to our climate and to ocean chemistry, lasting many thousands of years.”

The Carnegie Institution (www.CIW.edu) has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the U.S. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science. The Department of Global Ecology, located in Stanford, California, was established in 2002 to help build the scientific foundations for a sustainable future. Its scientists conduct basic research on a wide range of large-scale environmental issues, including climate change, ocean acidification, biological invasions, and changes in biodiversity.