Is Your SUV Warming the Planet?


By driving your SUV, are you sentencing the planet to environmental devastation? Recently, the Clinton Administration released its National Assessment on Climate Change and America, a catalogue of potential disasters resulting from global warming. With admirable understatement, a headline in the news section of the Wall Street Journal noted that the study, "May Overplay Dire Side". Yeah, just maybe. Floods, droughts, disappearing coasts and killer microbes all run wild in the study, which somehow manages to preview possible harm resulting from both too much rain and too little.

The report has not been published in a peer-reviewed scientific journal, but it's sure to help shame Americans into accepting limits on our economic growth. Well, before you abandon your Jeep Cherokee, you might want to learn about another study which did appear in a peer-reviewed scientific journal. And its message is a little different.

Perhaps the most important—yet most politically inconvenient—study in the history of the global warming debate is the one generated by Princeton University's Carbon Modeling Consortium and published in Science magazine in 1998. A team of researchers led by Princeton's Jorge Sarmiento identified a "carbon sink" in North America. In other words, the land in North America was absorbing a surprisingly large amount of the carbon dioxide that would otherwise become greenhouse gas in the atmosphere. The technical term is "terrestrial uptake" but the message is clear: Increases in greenhouse gases are coming from outside North America.

Dr. Sarmiento told us this week, "According to our results, for the 1988 to 1992 period we analyzed, North America was a net emitter of about 0." That's right, zero. As close as these scientists from Princeton, Columbia and the government's National Oceanic and Atmospheric Administration (NOAA) can guess, the grass and trees on our continent are consuming all the CO2 emitted by our cars and factories. So the North American continent on its own is not increasing the amount of greenhouse gases in the atmosphere. All of us industrialized, SUV-driving, big house-heating, spoiled Americans add up to a wash, in terms of carbon emissions.

How is this possible? In 1998, the Princeton team offered this explanation: "there are a number of possible mechanisms that could be responsible for the sink. Forest regrowth in areas where generations of pioneers leveled trees to create farmland almost certainly plays an important role. Millions of acres east of the Mississippi have returned to forest.

"Forest regrowth, and carbon absorption, in North America may be enhanced by some side effects of industrialization. Nitrogen deposition (a dilute form of acid rain) caused by combustion processes in automobiles and power plants can act as a fertilizer, as can the higher concentrations of atmospheric carbon dioxide in the air. Global warming can contribute to longer growing seasons, which have been observed in studies of satellite measurements cited by the team."

So, thanks to robust forest growth, all our CO2-munching trees can absorb the greenhouse gases from our energy use. Does this mean there isn't a potential problem due to global warming? No. But it does mean that the current political solution embodied in the Kyoto agreement, in which the United States accepts strict limits on its energy use, while most of the world is free to continue emitting increasing amounts of CO2, has no justification in science. The scientific threat has been used as a pretext to cut a political deal, and it's a bad one for America—a redistribution of wealth from the United States to the rest of the world. I understand why this sounds like a great idea in less developed countries, but why anyone in the US would endorse it is beyond me.

Instead of putting the brakes on our growth, and punishing the one region of the planet that's not making a net contribution to greenhouse gases, perhaps other countries should follow our lead in creating a high-tech economy. With all our industry, we manage to live in a carbon sink because we have abundant, growing forests. In other words, we are very efficient in our use of land, so there are plenty of plants and trees to absorb our CO2. We favor energy sources that leave a tiny footprint on the land oil and gas—as opposed to low-tech energy sources that require us to clear more land wood burning, solar panels, windmills and coal. Of course, the most land-efficient, non-polluting energy source of all is nuclear power. Nuclear plants don't emit greenhouse gases and they leave a tiny footprint on the land. Until politicians are ready to go nuclear, it's hard to take their predictions of doom seriously or to buy into their alleged solutions.