Scientific American: A global deal to combat climate change lurches toward reality in Lima, Peru, this week--and yet any politically feasible agreement will be insufficient to restrain continued warming of global average temperatures, perhaps uncomfortably high. Although recent pledges by China, the 28 countries of the European Union and the U.S. are the first signs of the possibility of restraining the endless growth of greenhouse gas pollution on a long-term basis, atmospheric concentrations of carbon dioxide have...