In 2001, the Intergovernmental Panel on Climate Change (IPCC) released a landmark report projecting average global surface temperatures to rise between 1.4 degrees and 5.8 degrees Celsius (roughly 2 to 10 degrees Fahrenheit) by the end of this century. Based on this forecast, author Mark Lynas outlines what to expect from a warming world, degree by degree. At 1 degree Celsius, most coral reefs and many mountain glaciers will be lost. A 3-degree rise would spell the collapse of the Amazon rainforest, disappearance of Greenland's ice sheet, and the creation of deserts across the Midwestern United States and southern Africa. A 6-degree increase would eliminate most life on Earth, including much of humanity.

Based on authoritative scientific articles, the latest computer models, and information about past warm events in Earth history, Six Degrees promises to be an eye-opening warning that humanity will ignore at its peril.