So far, though, Gray's managed to continue his research and arrive at a conclusion of his own: "I believe that for the next twenty years, there will be a slight global cooling."
The three main greenhouse gases--carbon dioxide, methane and water vapor--are naturally occurring. Mother Earth produces about 200 million metric tons of carbon dioxide a year, to which man currently adds about 10 million metric tons, mostly by burning the fossil fuels oil, coal and natural gas. In the distant past, there was even more carbon dioxide in the atmosphere than there is today. But in the last forty years, scientists agree, there's been a 33 percent increase.
Without greenhouse gases, life could not survive. For one thing, plants need carbon dioxide like we need oxygen, which plants provide. For another, the planet would be too cold. When sunlight warms the Earth's surface, the surface radiates the heat back into the atmosphere, where gases absorb about 70 percent of it; the rest escapes into space.
The more gases in the atmosphere, global-warming proponents theorize, the hotter it's going to get. That's the simple explanation of the greenhouse effect that has so many scientists worried.
According to Roger Pielke, though, climate is not a simple A causes B, but rather a complex interaction of thousands of variables between the atmosphere, the oceans and land. Pielke, whose paper-strewn cubicle is a few doors down from Gray's office, says the climate modelers have failed to account for many of those variables. In particular, they don't understand the intricacies of his own specialty: the effect of land use on climate change.
Pielke says studies he conducted recently showed that evaporation of water from irrigated land around Fort Collins had a cooling effect, just like the evaporation of sweat cools a runner's body. In fact, temperatures in that area were about 8 degrees cooler than in a non-irrigated short-grass prairie area just to the east. Pielke only recently published his findings, in which he asserts that "land-use change is a major contributor to climate on a local, regional and global level."
Unlike Gray, Pielke does not doubt that man has contributed to climate change. The eastern forests that Europeans found when they came to this country are largely gone; today forests are disappearing in Africa, Asia and South America. All of that changes the climate, he says, but to what extent is still a matter of guesswork. "We're fooling ourselves if we think we can predict the future," Pielke adds.
And atmospheric scientists are going to have a particularly tough time making predictions, since they're not trained to study land surfaces. "I believe they're sincere people," Pielke says, "but they don't have the background to be making the predictions they do."
Rather than spending so much time, money and effort on something that may or may not happen in the future, Pielke believes we should focus our resources on current risks. "In Denver, would we be better off spending our money on cutting carbon dioxide emissions or carbon monoxide from automobiles?" he asks. "And elsewhere in Colorado, is it more important to put our resources toward the quality and quantity of water or questioning the right or wrong of burning of fossil fuels?"
If the Kyoto conference calls for drastic emissions cuts, he says, it's "jumping the gun. What's the bigger threat in Africa? Disease or global warming?"
As the editor of the respected Journal of Atmospheric Sciences, which publishes articles from either side of the global warming issue so long as they have been favorably reviewed by peers, Pielke says it's evident that there's no scientific consensus on global warming. Even the 1995 IPCC report, which global-warming proponents claim represents the opinion of the 2,400 scientists who participated, includes a caveat that not all of the scientists agreed with the conclusions.
"Unfortunately, there's a lot of labeling and name-calling going on," Pielke says. "The media keeps quoting the same people over and over again. Meanwhile, most of the people involved in climatology and meteorology have never been asked for their position. And because of the politics, a lot of them would now not want to talk publicly. I've talked to young scientists who say they'd be worried that their funding would be cut off."
He's experienced the censorship himself. A recent exhibit on global warming at the Denver Museum of Natural History initially included an article written by Pielke for the Christian Science Monitor--the only dissenting text in the display. But the article disappeared soon after the exhibit opened to the public.