c122.
For the uniqueness of high carbon dioxide concentrations in the atmosphere coexisting with icecaps at the poles, see Raymond T. Pierrehumbert, “Climate Change and the Tropical Pacific: The Sleeping Dragon Wakes”, in Proceedings of the National Academy of Sciences, 2000, cited in Cox (2005), pp 188–189. The research on abrupt changes is discussed in some depth in Cox (2005), chapters 7 and 8.