The British government released the "Stern Review" on global warming by Nicholas Stern, a former chief economist for the World Bank. As an economist, I tend to leave this topic to my Cato Institute colleague Pat Michaels, a professor of Environmental Sciences at the University of Virginia. Since Stern is also an economist, however, the rules of logic and evidence that economists use should also apply to this report.

"Economic forecasting over just a few years is a difficult and imprecise task," the review cautions, so forecasting technology a hundred years from now "requires caution and humility." Unfortunately, there is little caution or humility in this report.

The 27-page summary begins by saying, "The current level of greenhouse gases in the atmosphere is equivalent to around 430 parts per million (ppm) CO2, compared with only 280 ppm before the Industrial Revolution. These concentrations have already caused the world to warm by more than half a degree Celsius."

More specifically, that 54 percent increase of greenhouse gases was apparently associated with a warming of only 0.6 degrees Celsius, give or take two-tenths. Citing a 2001 survey of "high projections" for global warming, however, the report claims that a much smaller 28 percent increase in greenhouse gases by the year 2050 could result in a "global average temperature rise" exceeding 2 degrees.

Yet if we use the same rule-of-thumb now used to predict 2 to 3 degrees more global warming by 2050, the much larger increase in greenhouse gases ever since 1750-1850 should already have increased the average global temperature by at least 2 degrees. But it didn't.

Suppose this theory works this time, and the Earth actually warms by 2 to 3 degrees Celsius, putting aside what it means to average Chicago's winters with Key West's summers. The Stern report reluctantly concedes that places like Canada, Russia and Scandinavia would likely experience "higher agricultural yields, lower winter mortality, lower heating requirements and a possible boost to tourism."

Plants thrive in greenhouses, particularly fruits and vegetables. The report claims biodiversity would be at risk, as though no threatened species could possibly benefit from milder winters.

And the report thinks malaria would increase, as though mosquitoes are picky about the climate. My great-grandfather J. Mason Reynolds died of malaria in Grand Rapids, Mich., in 1891.

Naturally, The Washington Post seized this opportunity to complain that "Bush has declined to sign the 1997 Kyoto Protocol." Yet the United Nations just reported that from 2000 to 2004 greenhouse gas emissions increased 4.6 percent in Canada, 2.4 percent in Europe and 1.3 percent in the United States. Besides, as the Stern report notes, "most future emissions growth will come from today's developing countries, because of their more rapid population and GDP growth and their increasing share of energy-intensive industries."

As I have often noted, passenger cars are not nearly as large a share of greenhouse emissions as people think. In fact, this report's first graph shows transportation accounting for less than 14 percent of greenhouse gas emissions -- the same share as agriculture or industry. Trucks, buses and cars account for less than 10 percent of global greenhouse gas emissions. Electricity is a much bigger offender, which must be why Hollywood lefties are infatuated with electric cars. Continued...