Unfortunately, U.S. corn land produces only 50 gallons worth of gasoline per acre per year - against an annual gasoline demand of 135 billion gallons. New U.S. ethanol plants coming online could take 30 percent of next year's U.S. corn harvest for automobile fuel - an unprecedented diversion of the world's scarce crop- land. Supplying the Bush goal of 35 billion gallons of ethanol per year would currently force farmers to clear more than 200 million acres of Midwest forest to supply even 10 percent of our gasoline demand from corn ethanol.

Even without ethanol demand, farmers would need to triple existing crop yields over the next 40 years. Population growth is likely to produce a peak human population of 8 billion to 9 billion. Economic growth will raise the number of affluent consumers from today's 1.5 billion to 7 billion - accompanied by soaring demand for meat, milk, eggs and pet food.

World corn prices are already nearly double last year's level, and wheat prices are up 10 percent. Mexican consumers are in the streets, protesting a 60 percent increase in tortilla prices. Midwest economist Tom Elam says current oil prices will support corn at $4.50 per bushel. A serious drought or crop disease could drive corn to $6 per bushel.

Why did the environmental movement, which is pledged to defend the wildlands, silently approve Bush's corn ethanol diversion and risk a massive forest loss? I would guess it's because the world is currently building or planning more than 40 new nuclear power plants. The Greens didn't wage their 30-year campaign against fossil fuels just to produce a shift to nuclear; they want dramatic reductions in humanity's use of technology.

The Kyoto Protocol demands we eliminate at least 80 percent of the world's current energy sources. Solar power and windmills have proven woefully inadequate to supply our base energy needs. There is currently no cost-effective way to produce ethanol from cellulose sources such as wood chips or switchgrass.

Brazilian sugar cane is three times more efficient at converting sunlight to transport fuel, mainly because corn-growing takes more diesel fuel, more fossil-fueled fertilizer, and lots of natural gas to heat the conversion process. But even ethanol from sugar cane is more expensive than gasoline with oil at $65 a barrel.

The deeper reality is that fossil fuels probably aren't to blame for our global warming. Roman histories and modern studies of ice cores, seabed sediments and fossil pollen all agree that the world has a moderate, natural 1,500-year climate cycle. That cycle explains most, or all, of the planet's warming since 1850. There is no evidence that human-emitted CO2 has significantly increased global temperatures. We will probably have a moderate warming for the next several hundred years whether we burn fossil fuels or not. Then we will have centuries of colder weather.

Let's keep our trees. Let's forget the Kyoto Protocol. Instead, let's get rid of the trade barriers that prevent American farmers from selling their corn and meat to the increasingly affluent consumers in densely populated Asian countries. Then both our farmers and our urban consumers can move sustainably forward into the 21st century.

Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues <http://www.cgfi.org/> .