A stark mug shot of domestic terrorist Ted Kaczynski briefly took center stage in the increasingly ugly debate over climate change Friday as the Heartland Institute, a libertarian think tank funded by major corporations, launched a billboard campaign equating people convinced that global warming is real to the convicted killer.

“I still believe in Global Warming. Do you?” read big orange letters next to the Unabomber’s infamously grizzled face on an electronic billboard along the Eisenhower Expressway outside Chicago, the Heartland Institute’s home.

The billboard went live Thursday afternoon. But by 4 p.m. Eastern time, an outcry from allies and opponents alike led the Heartland Institute’s president, Joe Bast, to say he would switch off the sign within the hour.

“The Heartland Institute knew this was a risk when deciding to test it, but decided it was a necessary price to make an emotional appeal to people who otherwise aren’t following the climate change debate,” Bast wrote in an e-mail to some of the institute’s supporters, explaining his decision to end the campaign.

Rep. F. James Sensenbrenner Jr. (R-Wis.), scheduled to headline the Heartland Institute’s annual conclave of climate-change skeptics this month, said through a spokeswoman that he “will not participate in the upcoming climate-change conference if the Heartland Institute decides to continue this ad campaign.”

Sensenbrenner “wants nothing to do with this type of name-calling, which does more to distract from the issues at hand than advance a positive dialogue,” said the spokeswoman, Amanda Infield, who added that the congressman had expressed his displeasure to Bast.

Anthony Watts, a meteorologist and a vocal skeptic of mainstream climate science, called the billboard “unproductive,” akin to a “food fight.”

“I think Heartland is suffering battle fatigue,” said Watts, who runs a popular climate-skeptic Web site and who considers himself an ally of Heartland. “When you’re suffering battle fatigue, sometimes you make mistakes.”

Opponents of the Heartland Institute’s strategy of undermining climate science were predictably disgusted. Ken Caldeira, a prominent climate scientist at Stanford University, said, “Putting up these billboards is an act of desperation. They are unable to argue based on facts.”

Scott Denning, a Colorado State University climate scientist who has spoken at two Heartland Institute conferences, said, “It’s just awful. I hate that they did that.” Denning said he speaks at conferences to engage with people skeptical about mainstream climate science.

In announcing the ad campaign on its Web site, the Heartland Institute said it was also going to deploy images of Charles Manson, “tyrant” Fidel Castro and Osama bin Laden in future billboards.

“These rogues and villains were chosen because they made public statements about how man-made global warming is a crisis and how mankind must take immediate and drastic actions to stop it,” read the institute’s Web page.

Those plans are now scuttled.

Those who study public opinion of climate change said the inflammatory ads would probably backfire.

“The Heartland Institute is trying to associate everyone who believes in global warming — including the world’s scientific community, the Pentagon, the president, major companies, leaders of world religions, the nations of the world, and a majority of the American public itself — with terrorists,” said Anthony Leiserowitz of the Yale University Project on Climate Change Communication. “I strongly doubt this will move public opinion on global warming — at least not in the direction they were intending.”

The Heartland Institute made news earlier this year when internal documents appeared on liberal Web sites detailing the group’s funders and its strategy to promote climate-change skepticism to schoolchildren. Climate scientist Peter Gleick of the Pacific Institute for Studies in Development, Environment and Security admitted to duping the group into sending him the documents.