There are many reasons for investigating the climatic history of the Earth. First and foremost is the need to know how the climate of our planet has evolved over the last 600 million years (m.y.). Only by understanding past climate states of the Earth can we discern the driving mechanisms for global climate change, set boundary conditions for numerical modelling and learn how to predict future climates. Improved predictability of climate in the short-term future can be included among these advantages to be gained in the applied sense, as can using palaeoclimate information to predict the distribution of economically significant commodities such as petroleum, phosphorite, bauxite and the accumulation of other sedimentary minerals related to climatically controlled redox changes.

This book first describes, in a concise way, the salient features of Earth climates over the last 600 m.y. or so. With this background information in hand, our purpose is to recognize and then compare similar climatic states in history (e.g. the warm intervals in the early Palaeozoic and in the late Mesozoic), so as to determine whether major episodes display any significant similarities. In cases where strict parallelism seems to exist, whether for relatively warm or cool, wet or dry, or seasonally comparable global conditions, the description of climate for any one interval perhaps can be broadened by inferences from conditions in another interval, for which circumstances may be better known. Thus, we adopt an approach of comparative palaeoclimatology, in the hope that pooled information will provide new insights into the evolution of climate on Earth.

Palaeoclimatologists appear to be inveterate seekers after causes of change and the authors of this book are no exception.