How much CO2 is too much?
David Archer
University of Chicago Department of the Geophysical Science,
Chicago IL 60637
[email protected]
When CO2 is released to the atmosphere, it equilibrates with the ocean and the land biosphere on a
relatively rapid time scale of decades to centuries. The airborne fraction of the CO2 diminishes somewhat
as the pH of the ocean is restored through CaCO3 net dissolution, and its final return to the solid earth will
be largely in the form of CaCO3, the product of the dissolution of the CaO component of igneous rocks on
land.
I will begin by showing the results of a new carbon cycle model intercomparison project called LTMIP
(Long tail model intercomparison project) to predict the fate and atmospheric lifetime of fossil fuel CO2.
Given these results (which are not substantially different from previous results in the literature using similar
models) I will explore the limits of allowable fossil fuel CO2 emissions if we are to avoid “dangerous
anthropogenic interference” in the climate system, both through the initial CO2 peak, and through the long
tail of the CO2 lifetime.
2008 Gussow-Nuna Geoscience Conference
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