The Skeptic

Celebrated and shunned, CSU's Bill Gray is taking heat in the global-warming debate.

From the outset, Gray's research revolved around the formation, intensity, structure and motion of tropical storms. Like Riehl, he believed passionately in getting down in the trenches, even if it meant getting up in the air. Every year he went to Florida to fly into storms and collect data. Coastal officials, insurance companies and others were keenly interested in developing a reliable method for forecasting the hurricane season, but the Atlantic storms showed tremendous variability from year to year, and nothing Gray was finding out seemed to indicate how active the season might be.

By looking further afield, though, he began to detect patterns. The answers weren't in Florida. Some of them were on the other side of the world. Teaching tropical meteorology had made Gray familiar with the years that the Pacific warming events known as El Niño were at their strongest; in those years, the Atlantic turned out to be less active. Then he began to notice a relationship between hurricanes in the Atlantic and strange winds in the tropics stratosphere known as QBIOs, short for quasi-biannual oscillation: The winds blow from a westerly direction for twelve to fourteen months, then reverse their course for another twelve to fourteen months. As weather balloons improved in the 1960s and researchers began to get better data on the winds, Gray was able to see that the westerly QBIOs were linked to major Atlantic storms. Other factors -- the amount of rain in West Africa, the sea-level pressure in the Caribbean -- also seemed to provide good indicators of the Atlantic storm season months in advance.

"The problem was that we'd been looking locally," Gray recalls. "You had to look globally."

Gray released his first public forecast for the upcoming hurricane season in 1984. He predicted seven actual hurricanes (five developed) and ten named storms (twelve became significant enough to be named). Over the years, the CSU team has fine-tuned its methods and now claims 95 percent accuracy in determining whether a given season is going to be above or below average; the annual prediction is eagerly anticipated and reported on in hurricane-prone states. (Gray and Klotzbach expect this year to be only somewhat less horrendous than 2005: nine hurricanes, including five monsters, and seventeen named storms).

Yet for all his renown as a forecaster, Gray is wary of any methodology that claims to accurately track weather more than a few days ahead. His own predictions rely a great deal on "hindcasting," looking at key conditions several months before the hurricane season begins and matching them up with similar conditions as documented in the historical data of previous years. He's convinced that the climate is far too complicated for even the most powerful computers to forecast accurately years in advance -- which is one of his quarrels with the global-warming crowd.

Gray accepts that the earth has gotten warmer over the past century, particularly in the past three decades. He doesn't deny that heat-trapping gases generated by human activity, particularly carbon dioxide, have increased significantly, too. But it's the connections that researchers have drawn between these developments, and the way they've transformed the data into computer-generated scenarios of decades-spanning disaster that has him gnashing his teeth.

Although many factors contribute to climate change, the most sinister component, in many scientists' view, is carbon dioxide. Thanks largely to the burning of fossil fuels, the atmospheric level of CO2 has shot up to 381 parts per million, 37 percent higher than pre-industrial levels, and the pace is accelerating. Yet by itself, CO2 is hardly a pervasive threat; even doubling its concentration in experiments doesn't seem to trap a great deal more heat. The interaction of CO2 and water vapor, a much more common greenhouse gas, is another matter. One of the primary tenets of global warming is that carbon dioxide acts as a water-vapor "trigger" high in the atmosphere, trapping enough heat to moisten the air. As the air retains moisture, it warms further, creating a positive-feedback loop that drives the temperature higher and higher and keeps more heat from escaping in the form of radiation into space.

Gray disputes this. He's convinced that the calculations of the warming proponents fail to take into account the effect of increased global rainfall (as a result of surface warming and evaporation) on upper-atmosphere water-vapor levels. He's argued that "rainfall efficiency" will increase, and so will heat loss to space -- compensating, for the most part, for the rising levels of CO2. The computer models have exaggerated the feedback loop, he insists, and don't realistically simulate complex oceanic and atmospheric processes. "That's a big flaw in the models," he says, "and it's going to do them in."

In his war on the feedback loop, Gray has an ally of sorts in Richard Lindzen, an MIT professor and ardent critic of "climate alarmism," who's theorized that the behavior of upper-level cirrus clouds could counteract the warming effects of CO2. Clouds are a tricky issue in climate projections, since they can reflect light energy as well as trap heat. But Lindzen's and Gray's arguments have been widely challenged -- including by each other. Gray has referred to Lindzen's theory as a red herring, while Lindzen has termed Gray's grasp of the theoretical as "frustratingly poor."

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