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Global Warning

What do you get when greenhouse gases inspire greenhouse guesses? A heated argument--but not much scientific agreement.

It's the long, multi-decade predictions that spark heated controversy.
Meehl admits that climate modeling has limitations. The largest, perhaps, involves clouds, which computer modelers have not been able to fit into their equations with any assurance of accuracy. Although clouds usually have a cooling effect on temperatures, some types of clouds hold in heat. Under NCAR's global-warming scenario, increased heat would cause more evaporation, which would in turn create more clouds. But would those clouds have a net cooling or warming effect?

Another problem is that the current computers, as fast and powerful as they are, deal with generalities over a large land area. Data fed into the computer comes from grid points on a map, but the grids are so large that one over Oregon, for instance, would include (moving west to east) the coast, the coastal range, the Willamette Valley, the Cascades and the desert of the Great Basin--which have widely varying climates.

Critics of climate modeling note that without fudging the data, computers have been unable to recreate present climate patterns--much less accurately predict future patterns. Computer models from various institutions agree more with each other than they do with the real world, Meehl acknowledges; in other words, they tend to make the same errors. For example, computer models have been able to predict El Nino occurrences, but for some reason the predictions are smaller than the real thing by as much as one-third.

But technological progress is being made, Meehl adds. Recently, NCAR modelers were able to match computer models to present conditions without fiddling with data. While that's not yet predicting the future accurately--most modelers agree the computers are ten years from getting that right--it's a step closer.

"The way I view this is that climate modelers are giving their best estimate with the tools we have," Meehl says. "The policy-makers can take that information, along with twenty other pieces of evidence from other sources, and use it as a whole to make their decisions."

The best decision they could make regarding the threat of global warming, Meehl says, is to adopt what has become known as a "no-regrets policy." Rather than making massive, economy-shaking commitments to cut emissions quickly, the no-regrets strategy calls for smaller steps to wean ourselves from fossil fuels--which will run out sooner or later, whether or not global warming is a real danger. That means focusing on more energy-efficient cars and buildings, and emphasizing research and development of other energy sources.

Meehl blames policy-makers and the media for exaggerating the accuracy claims of computer models--and for fanning the flames of debate. "There is a real danger in overselling the science," he says. Although the U.S. government spent about $1.7 billion in 1997 alone on computer-model development, federal funding doesn't fuel the alarming predictions about global warming, he insists. "If, by perfecting the models, I can 'prove' what's going to happen in fifty years," he adds, "then I've solved the problem. And that would be the end of my funding."

And the government isn't the only entity funding research. The energy industry has also joined the fray, sponsoring a campaign of "disinformation and personal attacks" to discredit global-warming proponents, Meehl says, adding, "I don't think anybody on the science side anticipated the response of the energy industry."

When scientists accept money from the energy industry, he says, it's akin to scientists being "bought off" by the tobacco industry. Fortunately, he adds, "the majority don't get into the policy debate. We let the science speak for itself."

And Meehl doesn't need to look to his computer models to know that the science of climate and weather is an uncertain one. "I have a friend who's a farmer in Brighton," he says. "Last May, which was real dry, I asked him how his crops looked, and he said terrible.

"In June it rained a lot, and when I asked, he said they looked great...You just never know about the weather."

Forty miles to the north of the NCAR citadel, the building housing CSU's atmospheric-sciences department also sits on a hill--a rather plain little hill of dirt and grasses that overlooks a water-treatment plant and the wind tunnels of the engineering department. A half-mile to the west looms a manmade wall of rock that holds back the waters of Horsetooth Reservoir.

There is no user-friendly weather trail here, only a collection of satellite dishes--large and small--pointing toward the sky. The building itself is a squat square of cubicles piled on top of and beside each other. No guided tours are offered; there's not much to see, anyway, except for the cluttered offices of the scientist/professors who work here.

William Gray occupies one of those offices, along with a jumble of boxes containing papers that had been stored in the basement of his west Fort Collins home until it was flooded by this past summer's deluge. "They even blamed that on global warming," Gray says. He doesn't try to hide his disgust for scientists who tend to blame every weather aberration--from the Fort Collins and North Dakota floods to the impending El Nino phenomenon--on global warming.

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