So the math isn't complicatedbut that doesn't mean it isn't intimidating. So far only the Europeans and Japanese have even begun to trim their carbon emissions, and they may not meet their own modest targets. Meanwhile, U.S. carbon emissions, a quarter of the world's total, continue to rise steadilyearlier this year we told the United Nations we'd be producing 20 percent more carbon in 2020 than we had in 2000. China and India are suddenly starting to produce huge quantities of CO2 as well. On a per capita basis (which is really the only sensible way to think about the morality of the situation), they aren't anywhere close to American figures, but their populations are so huge, and their economic growth so rapid, that they make the prospect of a worldwide decline in emissions seem much more daunting. The Chinese are currently building a coal-fired power plant every week or so. That's a lot of carbon.
Everyone involved knows what the basic outlines of a deal that could avert catastrophe would look like: rapid, sustained, and dramatic cuts in emissions by the technologically advanced countries, coupled with large-scale technology transfer to China, India, and the rest of the developing world so that they can power up their emerging economies without burning up their coal. Everyone knows the big questions, too: Are such rapid cuts even possible? Do we have the political will to make them and to extend them overseas?
The first questionis it even possible?is usually addressed by fixating on some single new technology (hydrogen! ethanol!) and imagining it will solve our troubles. But the scale of the problem means we'll need many strategies. Three years ago a Princeton team made one of the best assessments of the possibilities. Stephen Pacala and Robert Socolow published a paper in Science detailing 15 stabilization wedges"changes big enough to really matter, and for which the technology was already available or clearly on the horizon. Most people have heard of some of them: more fuel-efficient cars, better-built homes,
wind turbines, biofuels like ethanol. Others are newer and less sure: plans for building coal-fired power plants that can separate carbon from the exhaust so it can be "sequestered" underground. (See Illustration "How to Cut Emissions.")
These approaches have one thing in common: They're more difficult than simply burning fossil fuel. They force us to realize that we've already had our magic fuel and that what comes next will be more expensive and more difficult. The price tag for the global transition will be in the trillions of dollars. Of course, along the way it will create myriad new jobs, and when it's complete, it may be a much more elegant system. (Once you've built the windmill, the wind is free; you don't need to guard it against terrorists or build a massive army to control the countries from which it blows.) And since we're wasting so much energy now, some of the first tasks would be relatively easy. If we replaced every incandescent bulb that burned out in the next decade anyplace in the world with a compact fluorescent, we'd make an impressive start on one of the 15 wedges. But in that same decade we'd need to build 400,000 large wind turbinesclearly possible, but only with real commitment. We'd need to follow the lead of Germany and Japan and
seriously subsidize rooftop solar panels; we'd need
to get most of the world's farmers plowing their fields less, to build back the carbon their soils have lost. We'd need to do everything all at once.