The changes in the Earth's climate over the past 600 million years, from the Cambrian to the Quaternary, come under scrutiny in this book, first published in 1992. The geological evidence for ancient climates is examined, such as the distribution of climate-sensitive sediments. The Earth's climate has changed many times throughout the Phanerozoic. Thus in this book the climate history has been divided into Warm and Cool modes, intervals when either the Earth was in a former 'greenhouse' state with higher levels of atmospheric CO2 and polar regions free of ice, or the global climate was cooler and ice was present in high latitudes. The studies presented here highlight the complex interactions between the carbon cycle, continental distribution, tectonics, sea level variation, ocean circulation and temperature change as well as other parameters. In particular, the potential of the carbon isotope records as an important signal of the past climates of the Earth is explored. This book will be useful to all students and researchers with an interest in palaeoclimates and palaeoenvironments.

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Palaeomagnetic data suggest that the Earth was glaciated at low latitudes during the Palaeoproterozoic (about 2.4-2.2 Gyr ago) and Neoproterozoic (about 820-550 Myr ago) eras, although some of the Neoproterozoic data are disputed. If the Earth's magnetic field was aligned more or less with its spin axis, as it is today, then either the polar ice caps must have extended well down into the tropics-the 'snowball Earth' hypothesis-or the present zonation of climate with respect to latitude must have been reversed. Williams has suggested that the Earth's obliquity may have been greater than 54 degrees during most of its history, which would have made the Equator the coldest part of the planet. But this would require a mechanism to bring the obliquity down to its present value of 23.5 degrees. Here we propose that obliquity-oblateness feedback could have reduced the Earth's obliquity by tens of degrees in less than 100 Myr if the continents were situated so as to promote the formation of large polar ice sheets. A high obliquity for the early Earth may also provide a natural explanation for the present inclination of the lunar orbit with respect to the ecliptic (5 degrees), which is otherwise difficult to explain.