The rough consensus among climatologists these days is that, if we want to stave off the worst effects of global warming, we're going to have to stabilize carbon concentrations in the atmosphere at about 450 parts per million by mid-century (we're at about 383 ppm now). That means whopping emissions cuts, especially in the United States and Europe—but also in China, India, and elsewhere.

It all sounds so drastic, no? Except that a new OECD report calculates that reaching that goal could be done for cheap: The world's GDP in 2050 would be about 2.5 percent below what it otherwise would be if we did nothing. In other words, instead of being three-and-a-half times richer than we are now, we'll be like 3.4 times richer. (Figuring out how to distribute the costs fairly will be tricky, but hardly insurmountable.) So that right there is Al Gore's secret plan to impoverish us all.

Another theme in the report is that climate change isn't the only environmental problem in town. Water scarcity is becoming a bigger and bigger issue around the world, as Georgians and Arizonans no doubt know. So are various threats to biodiversity. Air pollution is choking China and India. The main point of the report, though, is that these things really can be tackled for a low price. And last I checked, the OECD isn't some radical hippie commune.

Meanwhile, this Bloomberg write-up notes that air pollutants cost the U.S. economy some $277 billion each year in health-related expenses. A friend half-jokingly mentioned to me the other day that you could probably do more to reduce health care costs by passing a cap-and-trade bill than by pushing for health care reform (not least in light of this recent study showing that increases in CO2 can worsen the adverse respiratory effects of ozone and other air pollutants). Who knows if that's true or not, although it probably would do wonders for public health if a climate bill provided incentives for, say, people to move to urban areas and walk and take public transit more.