Hot tempers on global warming

Meacham concedes that "those who doubt that greenhouse gases are causing significant climate change have long pointed to the 1975 Newsweek piece as an example of how wrong journalists and researchers can be." But rather than acknowledge that the skeptics may have a point, Meacham dismisses it.

"On global cooling," he writes, "there was never anything even remotely approaching the current scientific consensus that the world is growing warmer because of the emission of greenhouse gases."

Really? Newsweek took rather a different line in 1975. Then, the magazine reported that scientists were "almost unanimous" in believing that the looming Big Chill would mean a decline in food production, with some warning that "the resulting famines could be catastrophic." Moreover, it said, "the evidence in support of these predictions" - everything from shrinking growing seasons to increased North American snow cover - had "begun to accumulate so massively that meteorologists are hard-pressed to keep up with it."

Yet Meacham, quoting none of this, simply brushes aside the 1975 report as "alarmist" and "discredited." Today, he assures his readers, Newsweek's climate-change anxieties rest "on the safest of scientific ground."

Do they? Then why is the tone of Sharon Begley's cover story - nine pages in which anyone skeptical of the claim that human activity is causing global warming is painted as a bought-and-paid-for lackey of the coal and oil industries - so strident and censorious? Why the relentless labeling of those who point out weaknesses in the global-warming models as "deniers," or agents of the "denial machine," or deceptive practitioners of "denialism?" Wouldn't it be more effective to answer the challengers, some of whom are highly credentialed climate scientists in their own right, with scientific data and arguments, instead of snide insinuations of venality and deceit? Do Newsweek and Begley really believe that everyone who dissents from the global-warming doomsaying does so in bad faith?

Anthropogenic global warming is a scientific hypothesis, not an article of religious or ideological dogma. Skepticism and doubt are entirely appropriate in the realm of science, in which truth is determined by evidence, experimentation, and observation, not by consensus or revelation. Yet when it comes to global warming, dissent is treated as heresy - as a pernicious belief whose exponents must be shamed, shunned, or silenced.

Newsweek is hardly the only offender. At the Live Earth concert in New Jersey last month, Robert F. Kennedy Jr. denounced climate-change skeptics as "corporate toadies" for "villainous" enemies of America and the human race. "This is treason," he shouted, "and we need to start treating them now as traitors."

Some environmentalists and commentators have suggested that global-warming "denial" be made a crime, much as Holocaust denial is in some countries. Others have proposed that climate-change dissidents be prosecuted in Nuremberg-style trials. The Weather Channel's Heidi Cullen has suggested that television meteorologists be stripped of their American Meteorological Society certification if they dare to question predictions of catastrophic global warming.

A few weeks ago, the Competitive Enterprise Institute's Marlo Lewis published an article opposing mandatory limits on carbon-dioxide emissions, arguing that Congress should not impose caps until the technology exists to produce energy that doesn't depend on carbon dioxide. In response to Lewis's reasonable piece, the president of the American Council on Renewable Energy, Michael Eckhart, issued a threat:

"Take this warning from me, Marlo. It is my intention to destroy your career as a liar. If you produce one more editorial against climate change, I will launch a campaign against your professional integrity. I will call you a liar and charlatan to the Harvard community of which you and I are members. I will call you out as a man who has been bought by Corporate America."

This is the zealotry and intolerance of the auto-da-fé. The last place it belongs is in public-policy debate. The interesting and complicated phenomenon of climate change is still being figured out, and as much as those determined to turn it into a crusade of good vs. evil may insist otherwise, the issue of global warming isn't a closed book. Smearing those who buck the "scientific consensus" as traitors, toadies, or enemies of humankind may be emotionally satisfying and even professionally lucrative. It is also indefensible, hyperbolic bullying. That the bullies are sure they are doing the right thing is not a point in their defense.

"The greatest dangers to liberty," Justice Louis Brandeis wrote, "lurk in insidious encroachment by men of zeal, well-meaning but without understanding."

Jeff Jacoby's column appears regularly in The Boston Globe.