I am a reporter on climate change. I have been following the topic for New Scientist magazine in the UK and others for twenty years now. And when I talk to climate scientists during their coffee breaks and at their private conferences--as I have done extensively both before and after completing this book--I hear them warn that the current accepted predictions could be much too optimistic; that their statistical models of climate, sophisticated though they undoubtedly are, badly underestimate the forces of change; that we could be close to triggering sudden lurches in the world's climate. Hence the subtitle of the book: Why Scientists Fear Tipping Points in Climate Change.