The international climate debate heats up

China, the United States and other world powers are focusing their energy ? or at least their speechmaking ? on climate change. But the biggest threat for those who hope to sound the alarm may be something other than melting polar ice caps: something experts call climate “stability.” Joining us to explain is Andrew Revkin, environmental reporter for The New York Times. Revkin writes the blog Dot Earth about humans and their effect on the planet.