Book excerpt: Earth’s climate varies even without human influence but the acceleration in the changing pattern with cause and effect by/to the civilisation is a matter of concern to scientists. These patterns are lessons to understand future trends and ways and means for mitigation. The extreme weather events in almost every region of the globe involving excessive loss of human life and property are causing anxiety in society and posing challenges before scientists and planners. Cyclical variations in the Earth’s climate occur at multiple time scales, from years to decades, centuries, and millennia. Cycles at each scale are caused by a variety of physical mechanisms. In the last 65 Ma only, there have been several cycles of glacial advances and retreat, with the abrupt end of the last ice age about 11,700 years ago marking the beginning of the modern climate era and human civilization. A multidisciplinary approach in studying the Earth’s changing climate will provide a holistic view and guide us in future planning and programming.