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. Intended for students, teachers, and general readers, this concise, user-friendly handbook addresses the major features of the science behind this complex topic. The authors explain the basis for the three central conclusions of modern climate science: the Earth is warming, humans are mainly responsible, and these changes will be extremely challenging for us to deal with.