How do we know that climate change is an emergency? How did the scientific community reach this conclusion all but unanimously, and what tools did they use to do it? This book tells the story of climate models, tracing their history from nineteenth-century calculations on the effects of greenhouse gases, to modern Earth system models that integrate the atmosphere, the oceans, and the land using the full resources of today's most powerful supercomputers. Drawing on the author's extensive visits to the world's top climate research labs, this accessible, non-technical book shows how computer models help to build a more complete picture of Earth's climate system. 'Computing the Climate' is ideal for anyone who has wondered where the projections of future climate change come from – and why we should believe them.