After years of negative reports, there may at last be good news on the climate change front.

A recent study in Science magazine suggests we can prevent global warming using technologies available today. The key question is: Do we really need to do so?

Researchers at Princeton University's Carbon Mitigation Project explored a wide array of options for stabilizing atmospheric carbon-
dioxide at a level that many scientists believe would prevent catastrophic man-made global warming.

Even if reducing the
carbon-dioxide emissions would help combat harmful global warming impacts down the road, the aggregate costs of the project's proposals probably would decimate the U.S. economy.

The Princeton researchers, indeed, acknowledge they examined only whether technology exists today to stabilize carbon-dioxide emissions. But costs do matter -- especially when millions of American jobs are at stake.

Few scientists have argued that it would be impossible to cut carbon-dioxide emissions; the question is at what cost, and would those costs be worth incurring.

The economic costs in industrialized countries of implementing either the Kyoto Protocol or domestic alternatives would be substantial -- reducing gross domestic product by billions of dollars in the United States and trillions of dollars worldwide, and swell the ranks of the jobless globally.

It hardly seems worth it with the fast-growing economies of developing nations such as China, India and Brazil exempt from carbon-dioxide restrictions. The accelerating carbon-dioxide emission rates of those three nations alone would offset the sacrifice of the advanced nations in reducing global warming.

To their credit, the Carbon Mitigation Project researchers recognize this fact and include developing nations in their proposals. However, developing nations have steadfastly refused to participate in any plans that restrict their energy use to combat global warming.

The unintended consequences of many of the project's proposals, if put into effect, could be dire.

For instance, one proposal calls for increasing the fuel economy of light trucks and cars to 60 miles per gallon, but reducing the size of motor vehicles increases the risk of death and injury to drivers and passengers and lowers their ability to transport goods.

Indeed, current fuel economy standards are estimated to have caused more than 46,000-traffic deaths. The laws of physics won't change, so more deaths can be expected should this proposal become law.

The project's researchers also propose replacing a large percentage of the world's coal-fired power plants with gas-fired or wind-powered plants. Coal is abundant compared to natural gas.

As increasing numbers of gas-powered electric plants come on line, natural gas prices will increase substantially -- this is already occurring -- making it less attractive. And for countries like the United States where demand for natural gas already exceeds supply, increasing the energy sector's reliance on imported natural gas exacerbates national security problems.

The researchers also propose displacing a significant amount of coal-powered electricity by increasing the amount of wind power by 50 times the current amount -- which means constructing more than 2 million wind turbines.

Wind power is expensive and that kind of wholesale construction would send energy prices skyrocketing. The environmental downside of wind power is substantial: Even the present small number of electricity-generating windmills slaughter thousands of birds and bats -- many of them endangered species.

The Princeton researchers also suggest building an additional 4 million wind turbines to generate the hydrogen needed to power hydrogen fuel-cell cars.

All told, their wind-power proposals would require more land than has been developed for industrial, residential and commercial uses in North America since European explorers first set foot on the continent more than 500 years ago.

Researchers also suggest global production of ethanol be increased exponentially to provide fuel for 100 times as many cars and trucks as it currently powers. That would require planting ethanol crops such as sugar cane and corn on more than one-sixth of the agricultural land in use.

With that land taken out of food production, one can only wonder how we will feed the
3 billion additional humans projected to reside on Earth over the next century. Clearing additional millions of acres to produce ethanol would spell disaster for the world's remaining forests and wetlands.

No one doubts that the Carbon Mitigation Project proposals are well-meaning, but the sad truth is that they would wreak economic and environmental disasters. The Princetonian scholars should swallow a robust draught of realism and return to their drawing boards.

H. STERLING BURNETT is a senior fellow at the National Center for Policy Analysis in Washington, D.C. This essay was distributed by Knight Ridder/Tribune Information Services.