Theories and opinions about climate change abound - from those claiming that human-induced climate change is already beyond control to those who express scepticism about the real extent of these changes. How should we weigh up the scientific evidence, and what role does climate change play in the history of the Earth? In this comprehensive history of the climate and climate change, Antonello Provenzale explains how the planetary climate system works and how the climate has evolved over millions of years. Starting from the catastrophic events that marked the early history of the Earth, including seas of magma, global glaciations and mass extinctions, he shows that the climate has fluctuated between hot and cold periods: at certain times, the Earth was hot and lush with forests, while at others it was almost entirely covered by a thick layer of ice. The mechanisms that determine the modifications of the climate are multiple and complex and include external factors, such as solar luminosity and variations in the Earth's orbit, as well as internal processes connecting the atmosphere, the oceans, the crust, the mantle and the biosphere, which comprises living organisms. While the climate has fluctuated a great deal in the long history of the Earth, there are two features of our current situation that are a source of real concern. First, the rise in temperature of the last 50 years has been extremely fast, making it difficult for the environment to adapt to the new conditions. Second, the human population is much greater than it was in the past, and this population needs water, food, energy and shelter to survive. If temperatures continue to rise as they have in recent decades, ours will not be an easy world in which to live. To appreciate what is at stake we need to understand how the climate works and how human activity is affecting it - not in order to save the planet, which will do just fine on its own and probably better without us, but to save ourselves.