Only in America. Two weeks after the Heartland Institute erected billboards equating belief in global warming with extremists like the Unabomber, two climate activism groups have returned fire. Al Gore's Climate Reality Project will soon erect a set of billboards in Chicago that ask "Who to believe on climate — Heartland? ... or EVERY National Scientific Academy in the world?"


Another group called Forecast the Facts was also planning a set of billboards that would have attacked specific corporate donors to the Heartland Institute. A mockup shown by the New York Times displays the Pfizer logo and the headline "We still support Climate Deniers. Do you?" Pfizer donated $130,000 to the anti-climate think tank in 2010.


Those Pfizer billboards won't be seen by drivers any time soon, though: Billboard company Clear Channel Outdoor has rejected them, saying the use of corporate logos violates fair use and trademark law. "There's a big difference between a public image of the Unabomber and a specific trademark in terms of legality," Clear Channel spokesperson Jim Cullinan told the Times. Cullinan told The Hill that the Unabomber billboards were approved because the photos were in the public domain.


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But Forecast the Facts accuses Clear Channel of lying. According to a statement the organization released May 17, Clear Channel told them in a phone conversation that they "would not approve a billboard that criticized corporations" and did not mention trademark law.


At least 11 major corporate donors have pulled their backing from the Heartland Institute since the Unabomber billboard, including PepsiCo, State Farm and General Motors. Pfizer remains a Heartland supporter. A Pfizer spokesperson told the Times that the company does not agree with the Heartland Institute's position on climate change, although it does agree with the group on issues related to health care.


Forecast the Facts also planned to criticize Microsoft and Comcast in its billboards. Microsoft has donated at least $10,000 to the Heartland Institute, and Comcast has donated at least $25,000. "Our goal was to highlight Pfizer and other corporations' support of the Heartland Institute," campaign manager Brad Johnson told the Times. "The question to ask is whether these corporations are based on a foundation of science or on a foundation of profit."


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Battle of the climate-change billboards rages on
After the Heartland Institute compared global warming to the Unabomber, two climate activism groups decided to strike back.