No one really knows

No one really knows either the costs of global warming or the costs of dealing with it.

Countless practical difficulties would arise in trying to wean the U.S. economy from today's fossil fuels. One estimate done by economists at the Massachusetts Institute of Technology found that meeting most transportation needs in 2050 with locally produced biofuels would require "500 million acres of U.S. land -- more than the total of current U.S. cropland." America would have to become a net food importer.

In truth, models have a dismal record of predicting major economic upheavals or their consequences. They didn't anticipate the present economic crisis. They didn't predict the run-up in oil prices to almost $150 a barrel last year. In the 1970s, they didn't foresee runaway inflation. "General equilibrium" models can help evaluate different policy proposals by comparing them against a common baseline. But these models can't tell us how the economy will look in 10 or 20 years because so much is assumed or ignored -- growth rates; financial and geopolitical crises; major bottlenecks; crippling inflation or unemployment.

The selling of the green economy involves much economic make-believe. Environmentalists not only maximize the dangers of global warming -- from rising sea levels to advancing tropical diseases -- they also minimize the costs of dealing with it. Actually, no one involved in this debate really knows what the consequences or costs might be. All are inferred from models of uncertain reliability. Great schemes of economic and social engineering are proposed on shaky foundations of knowledge. Candor and common sense are in scarce supply.