It's impossible to cut CO2 emissions...

It just won't happen, no matter who much politicians want it to happen...

The global-warming debate's great un-mentionable is this: we lack the technology to get from here to there. Just because Arnold Schwarzenegger wants to cut emissions 80 percent below 1990 levels by 2050 doesn't mean it can happen. At best, we might curb emissions growth.

Consider a 2006 study from the International Energy Agency. With present policies, it projected that carbon-dioxide emissions (a main greenhouse gas) would more than double by 2050; developing countries would account for almost 70 percent of the increase. The IEA then simulated an aggressive, global program to cut emissions based on the best available technologies: more solar, wind and biomass; more-efficient cars, appliances and buildings; more nuclear. Under this admitted fantasy, global emissions in 2050 would still slightly exceed 2003 levels.

One way or another, our assaults against global warming are likely to be symbolic, ineffective or both. But if we succeed in cutting emissions substantially, savings would probably be offset by gains in China and elsewhere. The McKinsey Global Institute projects that from 2003 to 2020, the number of China's vehicles will rise from 26 million to 120 million, average residential floor space will increase 50 percent and energy demand will grow 4.4 percent annually. Even with "best practices" energy efficiency, demand would still grow 2.8 percent a year, McKinsey estimates.