There are a few subjects that divide opinion more than climate change. What is the truth? Can the solution be found in a global political treaty or individual action? This Britannica guide gives a clear overview of the scientific evidence, from data showing how the atmosphere has changed in the last 4.5 billion years to more recent studies on the symptoms of a warming planet and the global effects of greenhouse gases, deforestation, and population. The guide introduces you to the possible solutions and to key figures in the debate, from the origins of environmentalism through to the Kyoto Protocol and beyond. In his wide-ranging introduction, Robert M. May, leading commentator and former President of the Royal Society, looks at the current scientific debates concerning climate change and shows how our actions can change the future.