Many Greens think that they have a good grip on the likely trajectory of the planet’s climate over the next 100 years. If we keep burning fossil fuels at current rates, their climate models tell them, we’ll face a meltdown on a much larger scale than Chernobyl’s, beginning with the polar ice caps. Saving an extra 400 million tons of coal here and there—roughly the amount of carbon that the United States would have to stop burning to comply with the Kyoto Protocol today—would make quite a difference, we’re told. But serious Greens must face reality. Short of some convulsion that drastically shrinks the economy, demand for electricity will go on rising.