Reporting from Washington — Citing e-mails that critics say cast doubt on global warming, congressional Republicans called on the Obama administration Wednesday to suspend efforts to combat climate change until the controversy is resolved.
In a letter to the Environmental Protection Agency, the lawmakers requested that a pending move to regulate greenhouse gases under the Clean Air Act be halted, along with plans to limit emissions from vehicles, power plants and other sources, "until the agency can demonstrate the science underlying these regulatory decisions has not been compromised."
At issue are more than 1,000 electronic messages that were apparently obtained and released by a computer hacker. Most involve scientists at the University of East Anglia's Climatic Research Unit in Britain, one of the few institutions in the world that collect the historical temperature data relied on by climate researchers.
At the heart of the controversy is whether human activity causes climate change. Skeptics argue that global temperatures may be warming naturally. They say that the e-mails suggest that scientists may have manipulated evidence to bolster their claims. The scientists dispute that and say that their words have been taken out of context.
Republicans used otherwise unrelated hearings Wednesday in the House and Senate to demand congressional investigations, but Obama administration officials and congressional Democrats pushed back.
"The e-mails do nothing to undermine the very strong scientific consensus . . . that tells us the Earth is warming, that warming is largely a result of human activity," Jane Lubchenco, who heads the National Oceanic and Atmospheric Administration, told a House committee. She said that the e-mails don't cover data from NOAA and NASA, whose independent climate records show dramatic warming.
The controversy flared up just before a summit in Copenhagen next week at which President Obama and other world leaders will attempt to make progress on an international climate-change treaty.
In some e-mails, a prominent climate scientist urges colleagues to destroy records rather than release them under public disclosure laws. In others, scientists appear to discuss how to discredit research they disagree with.
One of the leading figures in the scandal, East Anglia climate scientist Phil Jones, stepped down temporarily this week amid an investigation into his work and e-mails.
In a 1999 e-mail, Jones wrote of using a "trick" to hide an apparent decline in recent temperatures on a chart being prepared for a meteorological organization. Warming skeptics seized on the line, which Jones said was "taken completely out of context" because he was simply looking for a clearer way to chart global warming.
Critics have also focused on an e-mail from Penn State University scientist Michael Mann as evidence that climate researchers have sought to downplay findings indicating that the Earth warmed naturally 1,000 years ago.
In a 2003 e-mail, Mann said that "it would be nice to 'contain' the putative" Medieval Warm Period.
Mann said in an interview last month that the e-mail reflected his desire to identify exactly when the period began -- not to downplay it. He also said that he had declined to act on Jones' request to destroy e-mails sought under freedom of information laws.
Republicans who have long questioned global-warming science say that the e-mails show a pattern that undermines the theory of man-made global warming.
"One cannot deny that the e-mails raised fundamental questions concerning . . . transparency and openness in science," Sen. James M. Inhofe (R-Okla.) said at a hearing Wednesday.
Rep. F. James Sensenbrenner Jr. (R-Wis.), one of the authors of the letter to the EPA, said in a news release Wednesday that the e-mails "read more like scientific fascism than the scientific process. . . . It's time to take back the notion that the 'science is settled.' "
Some climate scientists have expressed alarm at the contents of the e-mails. But many scientists and environmental groups have aggressively challenged the notion that the messages undermine climate science.
"The body of evidence that human activity is a prominent agent in global warming is overwhelming," James McCarthy, chairman of the Union of Concerned Scientists, told Sen. Barbara Boxer (D-Calif.) in a letter Wednesday.
"People write ridiculous e-mails when they're in the middle of a fight," Boxer said. "To me, what's important is, e-mails aside, is there global warming? Is it being affected by human activity? And there's nothing out there that says otherwise."
Frank Warner in Allentown, Pa., contributed to this report.