Legislation to fight global warming has disappeared from Washington’s policy agenda, but the battle over climate science continues to escalate.

The latest skirmish culminated in the admission Monday night by Peter Gleick, a climate scientist and author, that he assumed a fake identity to obtain documents that would expose the inner workings of a climate skeptic group.

“My judgment was blinded by my frustration with the ongoing efforts — often anonymous, well-funded and coordinated — to attack climate science and scientists and prevent this debate, and by the lack of transparency of the organizations involved,” Gleick wrote in a post on his Huffington Post blog.

Gleick’s admission “is the latest in an escalating spiral of polarizing warfare between self-described ‘Climate Hawks’ and so-called Climate Deniers,” which leaves the majority of scientists and the public “caught in the crossfire,” American University professor Matthew C. Nisbet, who studies the issues, wrote in a blog entry.

“Climate change is trapped in this larger polarization process that’s happening in U.S. politics, and scientists are part of that,” Nisbet said in an interview. “What you’re seeing happening is some scientist activists and some climate leaders are actively mobilizing the scientific community, not just in the context of climate change, but in the context of the election.”

Challenging the link between the burning of fossil fuels and global warming — a connection the vast majority of scientists accept — has become a staple on the Republican presidential campaign trail. Former Pennsylvania senator Rick Santorum, who has surged in recent polls, has attacked not only President Obama but also Republican rivals Mitt Romney and Newt Gingrich for being too liberal regarding global warming.

On Sunday, Santorum told CBS’s “Face the Nation” he had attacked Obama for subscribing to “a phony ideal” placing the environment above the needs of man.

“This idea that man is here to serve the Earth as opposed to husband its resources and be good stewards of the Earth . . . I think that is a phony ideal,” Santorum said. “I think a lot of radical environmentalists have it upside down.”

Climate concerns also are helping fuel the ongoing dispute over whether to build the Keystone XL pipeline, which would transport energy-intensive heavy crude oil from Canada to the U.S. Gulf coast.

Even some scientists who are organizing to counter the claims of climate skeptics in public, such as University of Illinois atmospheric sciences professor Don Wuebbles, said he and his colleagues need to be careful in how they wage their fight.

“Scientists need to get out the truth, but we should not be playing games,” Wuebbles wrote in an e-mail. “So it is inappropriate to try to get information in an illegal manner, no matter how strongly we feel these groups out there are misrepresenting the science and how they are being manipulative of the public.”

Gleick, who studies the hydrological cycle, serves as president of the Pacific Institute for Studies in Development, Environment and Security in Oakland, Calif. He said he used someone else’s name to obtain internal documents from Heartland after receiving an anonymous memo containing information about its funders and about its “apparent efforts to muddy public understanding about climate science and policy.” Gleick said he then passed the documents on to journalists and climate experts. The DeSmog Blog posted the documents last week.

Heartland Institute president Joseph L. Bast, who described one of the documents the DeSmog Blog had posted as a “forged memo,” issued a statement Monday saying his group is considering legal action.

“Gleick’s crime was a serious one,” Bast wrote. “It has caused major and permanent damage to the reputations of the Heartland Institute and many of the scientists, policy experts and organizations we work with. A mere apology is not enough to undo the damage.”

Gleick’s actions were not the first time pirated e-mails have been widely distributed as part of the climate debate. In November 2009 hackers posted a slew of e-mails stolen from the University of East Anglia, which portrayed several prominent climate scientists as seeking to marginalize their critics. The incident, dubbed “Climate-gate,” increased public skepticism of the connection between burning fossil fuels and global warming, even though the scientists were cleared of any academic wrongdoing.

Penn State University professor Michael E. Mann, one of the scientists whose e-mails were exposed in 2009, said in an interview “there isn’t a moral equivalence” between Gleick’s behavior and the climate-gate hackers because the people who took the East Anglia e-mails used them to “distract policymakers” from curbing the nation’s carbon output.

“These actions may very well have mortgaged the future of our children and grandchildren,” Mann said. “They never came forward to apologize.”

Mann is currently the subject of a lawsuit brought by Virginia attorney general Ken Cuccinelli II (R) seeking to obtain e-mails Mann wrote while teaching at the University of Virginia between 1999 and 2005. The Virginia Supreme Court has heard arguments in the case, and is expected to issue a ruling soon.

Gleick’s lawyer, John Keker, suggested that any legal action by Heartland would become another front in the long-running climate battle.

“Dr. Gleick looks forward to using discovery to understand more about the veracity of the documents, lay bare the implications of Heartland’s propaganda plans and, in particular, determine once and for all who is truly behind Heartland and why,” he wrote in an e-mail.

Richard Lindzen, an atmospheric scientist at the Massachusetts Institute of Technology who has questioned whether climate change will cause effects as severe as some predict, said he has been struck by “the viciousness” of his opponents. But Lindzen feels obligated to keep questioning what Gleick and others say about climate change impact “because they’re lies, it’s that simple. What would you do if people were truly misrepresenting things, and it has consequences for society?”