Heat

This is an outstanding book - a call for action that must happen now if we are to avoid climate change spiralling out of control. Its strengths are that it describes the issues with great clarity and conjures up possible solutions for dealing with them. Not all of these seem politically or practically realistic, but in a way that's not the point: they demonstrate that action can be taken and climate change kept in check.
I would strongly recommend, as a companion volume, The Rough Guide to Climate Change, which in many ways is an easier book to get yourself up to scratch on the science and the issues. It is very clearly written, with excellent diagrams, ranges widely over issues and solutions, and demystifies in the way that Rough Guides are so good at.