Staffers removed the piece after global-warming proponents complained, Pielke says, "and that's not healthy in a democracy."
Debate is the fuel that propels science to higher planes. The process of submitting your theory to the review, criticism and challenges of peers is the crucible through which, historically, good science must pass before it is accepted as fact. Albert Einstein developed his theory of relativity in 1905, for example, but wouldn't accept the validity of his own work for some twenty years, and not until it was proved accurate by rigorous testing.
But scientists who support the global-warming theory warn there may not be time to wait for perfect scientific consensus on the subject: Global warming could soon reach a point where even if fossil-fuel burning is curtailed, the gases already in the atmosphere would continue heating the planet.
Like many other global-warming claims, that's debatable.
Most scientists agree that the average temperature of the Earth has risen 1 degree Fahrenheit over the past century. But most of that increase occurred in the first half of the century, not the second--when fossil-fuel burning pumped up the carbon-dioxide content of the atmosphere by 33 percent.
Global-warming proponents, noting that sea levels have risen four to ten inches over the past hundred years, predict further increases, as much as several feet, which would swamp low-lying islands and coastal cities. But sea levels overall have risen 300 inches since the last Ice Age, and critics of global-warming scenarios contend that the rate of rise has not increased recently.
NOAA has detected a 20 percent increase in extreme precipitation events (hard rains, heavy snowfalls) since 1900, a trend consistent with global warming due to more water vapor in the atmosphere. But even after eighteen years of use, NASA satellites have not recorded global warming. In fact, they've noted a slight cooling trend. Global-warming proponents, who used to contend that the satellite record had not been kept long enough to give an accurate picture, now claim that satellites cannot correctly measure low-altitude warming.
Computer modelers themselves have scaled back their earlier predictions, reducing their estimates of temperature increases by one-third and sea-level rise by 25 percent. By 1995, the IPCC panel was predicting that the average temperatures would rise just 3.6 degrees by 2100. Modelers say the revisions have been made because their equipment and knowledge is stronger. But global-warming opponents, who note that the predictions have gotten milder with each generation of computer models, say the disaster mindset of policy-makers is still based on those earlier, flawed calculations.
If they base their actions on these problematic predictions, critics claim, emissions cutbacks could cost the U.S. economy billions of dollars and as many as a million jobs. Global-warming proponents, however, note that industry also made exaggerated claims about economic horrors when laws combating CFCs and acid rain were passed; those doomsday scenarios never came true. The development of energy alternatives, these proponents say, could actually stimulate the economy and create jobs.
Since the release of the 1995 IPCC report, the fight over global warming has more closely resembled an election campaign than scientific discourse.
That year, Vice President Al Gore, who's been gearing for a run as the environmentalist president, belittled scientific critics of the global-warming hypothesis. He accused a "tiny minority of dissident scientists" of treating warnings about the greenhouse effect as the "empirical equivalent of the Easter Bunny."
This past July, Secretary of the Interior Bruce Babbitt went on National Public Radio to take the offensive against global-warming naysayers. "It's an unhappy fact that the oil companies and the coal companies in the U.S. have joined in a conspiracy to hire pseudo-scientists to deny the facts and then begin raising political arguments that are essentially fraudulent," he said. "I think the energy companies need to be called to account, because what they are doing is un-American in the most basic sense."
On July 24, Clinton entered the fray by kicking off a public-relations campaign to convince the American public that something must be done--and done now--about global warming. He invited to the White House seven scientists, including three Nobel Laureates, each of whom shared apocalyptic visions of heat waves, intense storms, tropical diseases moving north, famine and oceans swamping cities. Schneider, now a professor at Stanford University, was one of the seven. This past summer's floods were an "omen," he said. "The increasing frequency and magnitude of these could very well be the first signs that the canary in the cage is starting to quiver."
"The overwhelming balance of evidence and scientific opinion is that it is no longer a theory, but now a fact, that global warming is real," Clinton concluded after the meeting. He vowed that the United States would make a commitment to "realistic and binding" carbon-dioxide-emission limits at the upcoming treaty talks in Kyoto.