The mail brings an invitation to register for the 2009 International Conference on Climate Change, which convenes on March 8 in New York City. Sponsored by the Heartland Institute, a Chicago-based think tank, the conference will host an international lineup of climate scientists and researchers who will focus on four broad areas: climatology, paleoclimatology, the impact of climate change, and climate-change politics and economics.

But if last year’s gathering is any indication, the conference is likely to cover the climate-change waterfront. There were dozens of presentations in 2008, including: “Strengths and Weaknesses of Climate Models,” “Ecological and Demographic Perspectives on the Status of Polar Bears,” and “The Overstated Role of Carbon Dioxide on Climate Change.”

Just another forum, then, sounding the usual alarums on the looming threat from global warming?

Actually, no. The scientists and scholars Heartland is assembling are not members of the gloom-and-doom chorus. They dispute the frantic claims that global warming is an onrushing catastrophe; many are skeptical of the notion that human activity has a significant effect on the planet’s climate, or that such an effect can be reliably measured or predicted. Some point out that global temperatures peaked in 1998 and have been falling since then. Indeed, several argue that a period of global cooling is on the way. Nearly all would argue that climate is always changing, and that no one really knows whether current computer models can reliably account for the myriad of factors that cause that natural variability.

They are far from monolithic, but on this they would all agree: Science is not settled by majority vote, especially in a field as young as climate science.

Skepticism and inquiry go to the essence of scientific progress. It is always legitimate to challenge the existing “consensus” with new data or an alternative hypothesis. Those who insist that dissent be silenced or even punished are not the allies of science, but something closer to religious fanatics.

Unfortunately, when it comes to climate change, far too many people have been all too ready to play the Grand Inquisitor. For example, The Weather Channel’s senior climatologist, Heidi Cullen, has recommended that meteorologists be denied professional certification if they voice doubts about global-warming alarmism. James Hansen, director of the Goddard Institute for Space Studies, wants oil-company executives tried for “crimes against humanity if they continue to dispute what is understood scientifically” about global warming. Al Gore frequently derides those who dispute his climate dogma as fools who should be ignored. “Climate deniers fall into the same camp as people who still don’t believe we landed on the moon,” Gore’s spokeswoman told The Politico a few days ago.

But as the list of confirmed speakers for Heartland’s climate-change conference makes clear, it is Gore whose eyes are shut to reality. Among the “climate deniers” lined up to speak are Richard Lindzen, the Alfred P. Sloan Professor of Meteorology at MIT; the University of Alabama’s Roy W. Spencer, a pioneer in the monitoring of global temperatures by satellite; Stephen McIntyre, primary author of the influential Climate Audit blog; and meteorologist John Coleman, who founded the Weather Channel in 1982. They may not stand with the majority in debates over climate science, but - Gore’s dismissal notwithstanding - they are far from alone.

In fact, what prompted The Politico to solicit Gore’s comment was its decision to report on the mounting dissent from global-warming orthodoxy. “Scientists urge caution on global warming,” the story was headlined; it opened by noting “a growing accumulation of global cooling science and other findings that could signal that the science behind global warming may still be too shaky to warrant cap-and-trade legislation.”

Coverage of such skepticism is increasing. The Cleveland Plain Dealer’s Michael Scott reported last week that meteorologists at each of Cleveland’s TV stations dissent from the alarmists’ scenario. In the Canadian province of Alberta, the Edmonton Journal found, 68 percent of climate scientists and engineers do not believe “the debate on the scientific causes of recent climate change is settled.”

Expect to see more of this. The debate goes on, as it should.