The author gratefully acknowledges his Ph.D. supervisor L.C. Sloan for mentorship and support via National Science Foundation (NSF) grant ATM9810799 and the D. and L. Packard Foundation as well as the support of Gary Shaffer and the Danish Center for Earth System Science. Discussions with E. Brady, R. Caballero, M. Lyle, J.C. McWilliams, T. Moore, B. Otto-Bliesner, P. Pearson, D. Rea, and J. Zachos were welcome and informative. The CSM model, computer time, and graphics tools (NCL) were provided through NCAR by NSF, for which I am grateful.