Between AD 800 and 1000, during what is known as the Classic Maya Collapse, unrelenting drought caused the deaths of millions of Maya people and initiated a cascade of internal collapses that destroyed their civilisation. Linking global, regional, and local climate change, the author explores how atmospheric processes, volcanism, ocean currents, and other natural forces combined to create a climate that pried apart the highly complex civilisation of the tropical Maya Lowlands in the ninth and tenth centuries. Drawing on knowledge of other prehistoric and historic droughts, this is a compelling study of the relationship of humans to their natural and physical environment. The author develops a new, scientific explanation of why the Classic Maya failed to adjust their behaviour and culture to the climatic conditions, and why civilisations in general sometimes collapse in the face of radical environmental change.