This book describes the structure of the climate system, as well as the processes upon which the system runs, changes and operates. It also discusses a historical development of the science of climate changes that is presented from ancient times up to the late 1990s. Following this is a detailed description of important discoveries made since the late 1990s, which have led to creation of modern science of natural climate changes and human-induced climate changes. A unique feature of the book is that it contains a presentation of recently reported new theory and causes of natural variations of earthquakes as well as human-induced variations of earthquakes. Furthermore, this book also presents a new theory and causes of natural and human-induced variations in volcanic activity together with associated climate changes.