1. M. Pagani is in the Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA.
2. K. Caldeira is in the Department of Global Ecology, Carnegie Institution, Stanford, CA 94305, USA.
3. D. Archer is in the Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637, USA.
4. J. C. Zachos is in the Earth Sciences Department, University of California, Santa Cruz, CA 95064, USA.