Until a few months ago, you’d be hard-pressed to find a more classic climate skeptic than D.R. Tucker. A conservative author and radio talk show host, he didn’t buy the notion that greenhouse-gas emissions were causing temperatures to rise. He was pretty sure global warming was a hoax perpetrated by Al Gore and a cadre of liberal, grant-hungry scientists. Then Tucker did what partisan pundits and climate skeptics rarely do: He changed his mind.

“I was defeated by facts,” Tucker announced on FrumForum, the popular conservative blog. In an April 18 post, “Confessions of a Climate Convert,” Tucker told readers how he came to question the ideologies of the climate debate, examine the science, and conclude that global warming was, in fact, very real. Tucker’s post sent a giddy ripple through green circles and stoked the ire of his libertarian colleagues.

This sort of thing doesn’t happen often. Or at least, it doesn’t seem to. Only 48 percent of Americans believe that global warming is at least in part “a result of human activities,” according to a 2010 Gallup poll, down from 60 percent in 2007 and 2008.

Anthony Leiserowitz, director of the Yale Project on Climate Change Communication, attributes this decline to five factors: The economic collapse, a severe decrease in media coverage, weather events like “Snowmaggedon,” the efforts of the “denial industry” (the network of industry-funded think tanks and political advocacy groups that push skeptic views), and the “ClimateGate” debacle.

This shift toward climate-change skepticism makes Tucker’s “conversion” all the more remarkable. So how did it happen?

Leiserowitz has been documenting trends in American climate belief for the past decade. He divides American attitudes toward climate change into six categories: “alarmed,” “concerned,” “cautious,” “disengaged,” “doubtful,” and “dismissive.”

The “alarmed,” at one end of the spectrum, are the nation’s green activists and Prius-drivers. At the other end are the “doubtful” and “dismissive” climate skeptics. Leiserowitz calls these skeptics “naysayers,” and until recently they accounted for a small minority of Americans. When he began studying climate-change attitudes in 2002, naysayers accounted for just 7 percent of Americans. By last year, that number had risen to 26 percent. (By comparison, 23 percent are “cautious,” 31 percent are “concerned,” and 14 percent are “alarmed.”)

Tucker was a naysayer. “I bought into Rush Limbaugh’s view that the environmentalist movement was ‘the new refuge of socialist thinking,’ ” he tells me. Tucker figured Al Gore and Van Jones (Obama’s onetime green jobs adviser) were leading liberals in a plot that used the specter of climate change to snare more power. Leiserowitz would call this “dismissive” thinking.

Tucker’s conversion began when he read Morris Fiorina’s Disconnect, which outlines the way partisan divisions take shape between Democrats and Republicans, and points out that environmentalism used to be one of conservatives’ chief concerns. Tucker’s curiosity was piqued.

“Why was it that environmentalism was only associated with the Democratic party now? And it was from those political questions that I became open to the scientific questions,” Tucker says. “It went from politics to the science.”

After that, a friend convinced Tucker to take a look at the Intergovernmental Panel on Climate Change’s Fourth Assessment Report—the authoritative synthesis of the most recent peer-reviewed climate science. “Initially I was a bit skeptical. But I kept on reading it, and there was just so much evidence, and it was so detailed, and it was so backed up, and it was so documented, that I was like, ‘holy shit, this is for real.’ ”

In the months since then, Tucker has become an active proponent for climate legislation: He works with groups like the Citizens Climate Lobby, writes letters to his state representative in defense of the EPA, openly calls for a carbon pricing system, and continues to engage his libertarian friends on the issue.

But Tucker hasn’t found much solidarity since his confession. “I have not received any—any—emails or any contacts whatsoever from people who have said they’ve had a similar journey,” he says.

Before he wrote the piece, though, Tucker did meet two fellow climate converts: the married couple Susan and Roger Shamel, ex-Republicans from Bedford, Mass. They had converted back in 2006 after watching Gore’s An Inconvenient Truth. Before that, the Shamels had been “doubtful”s, in Leiserowitz’s terminology. Both were lifelong Republicans, though Susan’s commitment had begun to wane as the GOP attacked women’s reproductive rights.

After their daughter urged them to watch the film, they began researching climate issues, dropped their affiliation with the Republican party, and started the nonprofit Global Warming Education Network.

But since then, they have been largely unable to convince their friends and family of the veracity of climate science, and were eventually ostracized. “We found new friends,” Susan says wryly.

This is unsurprising—entrenched ideologies often simply trump facts. People are prone to what psychologists called “motivated reasoning”; we instinctively bend available data to support our preexisting beliefs. Which means that when confronted with facts alone, skeptics usually don’t budge.

That’s why Tucker had to question politics first, before wrestling with the science. And the Shamels’ slackening ideology likely opened the door to clear-headed analysis. Having friends and family members who are willing to goad you along helps, as does a willingness to open-mindedly wade through stuffy scientific reports. (More Americans have probably read War and Peace cover to cover than a single page of the IPCC’s 4th Assessment report.)

Skeptics’ reluctance to accept new information is a trait the physicist John Cook knows well. Cook runs Skeptical Science, a hugely comprehensive website aimed at rebutting climate skeptics’ arguments. But after running the site for five years, he can only confirm a single case of a skeptic recanting.

I asked Anthony Watts, the meteorologist who runs what may be the most popular climate-skeptic blog, Watts Up With That, what could lead him to accept climate science. A “starting point for the process,” he said, wouldn’t begin with more facts but instead with a public apology from the high profile scientists who have labeled him and his colleagues “deniers.”

Thankfully, most Americans remain persuadable. Polls reveal that most Americans’ opinion of climate is relatively fluid, and shaped largely by current events. “Much of the ebbing and flowing of climate attitude … best resembles water sloshing in a very shallow pan,” the New York Times’ longtime climate writer Andrew Revkin says, “A lot of waves, very little meaning.”

In other words, an extra-snowy winter may tip Americans toward “doubtful” and heat waves might lead them into “cautious” territory, but these events rarely have long-term effects. So general belief in climate change could rebound as the economy improves, or as the summers heat up. Of course, we’re liable to slosh right back—unless, like Tucker and the Shamels, we’ve been convinced thoroughly enough to join the ranks of the “concerned” or the “alarmed.” So what might lead the nation’s skeptics and undecideds towards such meaningful conversions?

For skeptics, it’d probably require dismantling major chunks of the “denial industry”— the multinational corporations, conservative think tanks, and partisan cable networks that have an interest in promulgating doubt about climate science. This won’t happen anytime soon.

The merely unconvinced need, above all, more and better exposure to the science. Schools should provide better climate education in their science curricula, and media outlets need to improve their coverage. With the scientific evidence growing ever more incontrovertible, and the impacts of warming becoming increasingly visible, it’s possible that more and more Americans will slosh towards “concerned”—and stay there.