There are many uncertainties concerning climate change, but a rough international consensus has emerged that a doubling of atmospheric carbon dioxide from its pre-industrial baseline is likely to lead to a 2.5 degree centigrade increase in the earth's mean surface temperature by the middle of the next century. Such a warming would have diverse impacts on human activities and would likely be catastrophic for many plants and nonhuman animals. The author's contention is that the problems engendered by the possibility of (...) climate change are not purely scientific but also concern how we ought to live and how humans should relate to each other and to the rest of nature; and these are problems of ethics and politics. (shrink)