Last week some commenters wondered why I hinted that radically reducing greenhouse gasses in the present environment ran the risk of impoverishing people. I had in mind two things: (1) our nonsensensical government policy promoting ethanol, which appears to have contributed to a worldwide run-up in food prices, leading to disasters for many poor people around the world, and (2) the stated goals of all three major candidates to reduce US emissions to per capita levels not known here since before the Industrial Revolution.

In the Wall Street Journal, Steven Hayward, who knows a lot more about such things than I do, expresses my inchoate second thought in detail:

The usual chorus of environmentalists and editorial writers has chimed in to attack President Bush's recent speech on climate change. In his address of April 23, he put forth a goal of stopping the growth of U.S. greenhouse gas emissions by the year 2025. "Way too little and way too late," runs the refrain, followed by the claim that nothing less than an 80% reduction in emissions by the year 2050 will suffice -- what I call the "80 by 50" target. Both Hillary Clinton and Barack Obama have endorsed it. John McCain is not far behind, calling for a 65% reduction.

We all ought to reflect on what an 80% reduction of greenhouse gas emissions by the year 2050 really means. When we do, it becomes clear that the president's target has one overwhelming virtue: Assuming emissions curbs are even necessary, his goal is at least realistic.

The same cannot be said for the carbon emissions targets espoused by the three presidential candidates and environmentalists. Indeed, these targets would send us back to emissions levels last witnessed when the cotton gin was in daily use. Begin with the current inventory of carbon dioxide emissions -- CO2 being the principal greenhouse gas generated almost entirely by energy use. According to the Department of Energy's most recent data on greenhouse gas emissions, in 2006 the U.S. emitted 5.8 billion metric tons of carbon dioxide, or just under 20 tons per capita. An 80% reduction in these emissions from 1990 levels means that the U.S. cannot emit more than about one billion metric tons of CO2 in 2050.

Were man-made carbon dioxide emissions in this country ever that low? The answer is probably yes -- from historical energy data it is possible to estimate that the U.S. last emitted one billion metric tons around 1910. But in 1910, the U.S. had 92 million people, and per capita income, in current dollars, was about $6,000. By the year 2050, the Census Bureau projects that our population will be around 420 million. This means per capita emissions will have to fall to about 2.5 tons in order to meet the goal of 80% reduction.

It is likely that U.S. per capita emissions were never that low -- even back in colonial days when the only fuel we burned was wood. The only nations in the world today that emit at this low level are all poor developing nations, such as Belize, Mauritius, Jordan, Haiti and Somalia.

Excessive environmentalism, if actually implemented, would lead to poverty, and poverty leads to death. If a solution is to be found, wealth — and the technology that wealth buys — will play a big part.