KQED: On Sunday, the United Nations released one of its bluntest and bleakest reports to date on the dangers of global warming. The study from The Intergovernmental Panel on Climate Change (IPCC) warns that the world must cut nearly all greenhouse gas emissions by 2100 in order to head off the worst effects of climate change. U.N. Secretary General Ban Ki-moon urged world leaders to act, saying that the science is unambiguous. We speak with three authors of the report about future impacts of climate change...