For their guidance and patient assistance at various stages of this project, I am indebted to many earth scientists, most particularly to Chester C. Langway Jr., Richard B. Alley, Kendrick Taylor, Lisa K. Barlow, Jonathan T. Overpeck, James W. C. White, James P. Kennett, John M. Wallace, Wallace S. Broecker, Gerard C. Bond, Gavin A. Schmidt, Spencer R. Weart, and Ronald A. Liston.
Thanks also to Jeffrey Robbins, senior editor at Joseph Henry Press, for his valuable help.