Bill Clinton introduced the morning plenary today by, once again, honoring the companies and people who've committed to the Clinton Global Initiative to take steps to increase energy efficiency and decrease greenhouse-gas emissions.

But he touted one dubious statistic: If China, India, and the United States were to become as efficient as Japan, that would decrease global greenhouse-gas output by 20 percent. That statistic is based on this study by the McKinsey Institute and I think it's true only if, in an era of enhanced efficiency, the 2.5 billion people in China, India, and the United States didn't respond to resulting lowered energy costs by actually consuming more energy.

Still, it would be a huge step forward, and I suppose it's better that Bill Clinton's up there making this all seem possible, rather than pointing out the obvious challenges.