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Friday, May 2, 2008

Human-made carbon emissions 100 times what Earth can manage

It may sound ultra-hippy but it's hardcore science: for at least 610,000 years Earth has managed to keep a very tight balance of atmospheric carbon, with a variance of just 1-2%. Now we are challenging that finely tuned balance with releases that ammount to 100 times what Earth has ever been confronted with, so it is virtually impossible that our mother planet will be able to correct our wrongdoings.

This finding, already suspected, was made by K. Cladeira of Carnegie Institution for Science and R. Zeebe of the University of Havaii.

When carbon dioxide levels in the atmosphere rise, the chemical reactions that break down silicate minerals in soils are accelerated. Among the products of these reactions are calcium ions, which dissolve in water and are washed to the ocean by rivers. Marine organisms such as mollusks combine the calcium ions with dissolved carbon dioxide to make their shells (calcium carbonate), which removes both calcium and carbon dioxide from the ocean, restoring the balance.

The researchers found that over hundreds of thousands of years the equilibrium between carbon dioxide input and removal was never more than one to two percent out of balance, a strong indication of a natural feedback system. This natural feedback acts as a thermostat which is critical for the long-term stability of climate. During Earth's history it has probably helped to prevent runaway greenhouse and icehouse conditions over time scales of millions to billions of years — a prerequisite for sustaining liquid water on Earth's surface.
The Carnegie Institution's press release concludes with a most alarming remark by 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.
As a chain smoker, I know well that slow stupid suicidal is a very human possibility. No kidding.

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