We live in a world that is increasingly vulnerable to climatic shocks - affecting agriculture and industry, government and international trade, not to mention human health and happiness. Serious anxieties have been aroused by respected scientists warning of dire perils that could result from upsets of the climatic regime. In this internationally acclaimed book, Emeritus Professor Hubert Lamb examines what we know about climate, how the past record of climate can be reconstructed, the causes of climatic variation, and its impact on human affairs now and in the historical and prehistoric past. This 2nd Edition includes a new Preface and Postscript reviewing the wealth of literature to emerge in recent years, and discusses implications for a deeper understanding of the problems of future climatic fluctuations and forecasting.