In visiting the Heartland Institute's second International Conference on Climate Change, which concluded yesterday in New York, one couldn't help but be impressed by the change in mood among the 800 global warming skeptics gathered there.

Many of the scientists present felt that the intellectual tide had finally started to turn away from the conclusions of the United Nations' Intergovernmental Panel on Climate Change. That panel concluded global temperatures may already have reached crisis levels, and that human release of carbon emissions into the atmosphere was a major factor.

While it was fascinating to interview noted scientists who have renounced some of their earlier support for global warming theory, my most memorable exchange was with Alexander Cockburn, the left-wing columnist for the Los Angeles Times and the Nation magazine. Mr. Cockburn has undergone blistering attacks since he first dissented from the global warming "consensus" in 2007. "I've felt like the object of a witch hunt," he says. "One former Sierra Club board member suggested I should be criminally prosecuted."

Mr. Cockburn was at the conference collecting material for his forthcoming book "A Short History of Fear," in which he will explore the link between fear-mongering and climate catastrophe proponents. "No one on the left is comfortable talking about science," he told me. "They don't feel they can easily get their arms around it, so they don't think about it much. As a result, they are prone to any peddler of ideas that reinforce their pre-existing prejudices. One would be that there is a population explosion that must be dealt with by slowing down economies."

I asked him how he felt hanging around with so many people who have a more conservative viewpoint than he does. "It's been good fun and I've learned a lot," he told me. "I think what they are saying on this topic is looking better and better."