Climate change will likely be the major environmental - and perhaps economic and social - issue of the twenty-first century. It is controversial, confusing, and hugely important. This book is a concise, user-friendly handbook that addresses the major features of the science behind this very complex topic. The authors explain - clearly and with a minimum of jargon - the basis for the three central conclusions of modern climate science: that the Earth is warming, that humans are mainly responsible, and that these changes will be extremely challenging for humans to deal with.