Congressional Republicans called on the Obama administration Wednesday to suspend its efforts to combat climate change until the controversy is resolved over recently disclosed e-mails that critics say raise questions about the scientific underpinnings of the climate change issue.

WASHINGTON — Congressional Republicans called on the Obama administration Wednesday to suspend its efforts to combat climate change until the controversy is resolved over recently disclosed e-mails that critics say raise questions about the scientific underpinnings of the climate change issue.

In a letter to the Environmental Protection Agency, the GOP 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."

The e-mail controversy centers on more than 1,000 electronic messages that were apparently obtained and released by a computer hacker. Most of them involve scientists at the University of East Anglia's Climatic Research Unit in Britain, one of the few institutions in the world that collects the historical temperature data relied on by climate researchers.

At the heart of the controversy is the role of human activity such as burning coal and petroleum in climate change. Skeptics argue that global temperatures may be warming naturally. They say the e-mails suggest scientists may have cooked the books and manipulated evidence to bolster their claims.

Among the e-mails are messages that show a prominent climate scientist urging colleagues to destroy records to avoid releasing them under public disclosure laws. In others, scientists appear to discuss how to discredit published research they disagree with.

One of the leading figures in the scandal, East Anglia climate scientist Phil Jones, stepped down temporarily this week in the face of a government 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 global temperatures on a chart being prepared for use by a meteorological organization. Warming skeptics seized on the line, which Jones said has been "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 play down evidence that the Earth warmed naturally 1,000 years ago.

In a 2003 e-mail, Mann said "it would be nice to 'contain' the putative" Medieval Warming Period. Mann told Tribune Newspapers last month that the e-mail reflected his desire to identify exactly when the period began — not to downplay it. He also said he declined to act on a request from Jones to destroy e-mails sought under Freedom of Information laws.

Republicans who have long questioned global warming science say the e-mails show a pattern that undermines the entire theory of man-made global warming. "One cannot deny that the e-mails raised fundamental questions concerning ... transparency and openness in science," Sen. James Inhofe, R-Okla., said at a hearing on Wednesday.

Rep. Jim Sensenbrenner, R-Wisc., one of the authors of the letter to the EPA, said in a news release on 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.' "

In the House and Senate, the Republicans used otherwise unrelated hearings to demand congressional investigations of the scandal.

Obama officials and congressional Democrats pushed back, defending the science of climate change and efforts to regulate the heat-trapping gases scientists blame for warming the planet.

"People write ridiculous e-mails when they're in the middle of a fight," Sen. Barbara Boxer, D-Calif., 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."

But the controversy has been especially unsettling to administration officials and environmentalists because it has flared up on the eve of a summit conference in Copenhagen next week at which President Barack Obama and other world leaders will attempt to make progress on an international climate change treaty.

Some climate scientists have expressed alarm at the contents of the e-mails. Many scientists, and a host of environmental groups, have aggressively challenged the notion that the messages undermine climate science.

"The body of evidence that human activity is prominent agent in global warming is overwhelming," James McCarthy, a former Intergovernmental Panel on Climate Change lead author and board chair of the environmental group Union of Concerned Scientists, told Sen. Barbara Boxer, D-Calif., in a letter Wednesday.

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(Frank Warner of Tribune Newspapers contributed to this report from Allentown, Pa.)

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