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President Obama faces no easy task in uniting dozens of bickering nations toward the goal of tackling climate change at an international conference in Copenhagen next week. But as if that weren't hard enough, a slew of leaked e-mails in the run-up to the conference has only fueled global warming skeptics who say the cause is bunk.

The president announced last week that he would attend the United Nations meeting, in a bid to drive some manner of agreement to set new greenhouse gas emissions targets -- though a legally binding deal is unlikely.

But shortly before his announcement, hackers broke into the servers at the Climatic Research Unit of the University of East Anglia in Great Britain and posted e-mails in which scientists dismissed climate change skeptics, expressed concern about the lack of evidence to prove the threat of global warming and even made one reference to a plan to "hide the decline" in temperatures.

The leak muddied the climate change waters, leading one Republican, Sen. James Inhofe, to call for an investigation. The Heritage Foundation's Ben Lieberman said the e-mails serve to undercut the entire Denmark conference.

"This raises questions about some of the very U.N. science that forms the basis of what's going to be discussed in Copenhagen," he said. "There's a lot to be concerned about here. At the very least the president shouldn't agree to anything in Copenhagen until we get to the bottom of Climate-gate and find out just how much there is to global warming scientist that we can still trust."

In the wake of the e-mail leak, university scientists say raw data from the 1980s was thrown out. While the scientists said they kept a different kind of data, skeptics say that amounts to a plea of "trust us."

Despite a recent decline in global temperatures, the trend over the past 150 years has shown temperatures rising -- but the timing of the e-mail scandal is perfect for skeptics, said Heather Conley, senior fellow with the Center for Strategic and International Studies.

"It doesn't negate the fact that the global community does need to address its rate of emitting carbon and it needs to develop clean and greener technologies, but it does continue to throw this debate out there," she said.

The president's climate czar, former EPA administrator Carol Browner, said she's sticking with scientists who believe in man's impact on global warming. And the White House is also shrugging off the e-mails.

"I think there's no real scientific basis for the dispute of this," White House Press Secretary Robert Gibbs said.

Another potential complication for Obama is that he's dropping by Copenhagen toward the start of the two-week conference on his way to collect the Nobel Peace Prize in Oslo. That timing could reduce the impact his presence might have, experts said, since the heavy lifting will likely not be done in the first few days.

"Somewhere up towards 70 heads of state and government will be converging on Copenhagen. Again, it's a sign of their own commitment to the results, but you're not going to get that the second or third day of this meeting. You're going to get it at the very end," Conley said.

But the White House said the timing of the president's visit is immaterial.

"I think the president believes that that visit happening at the beginning is just as important as it would be at any point to getting that deal going quicker," Gibbs said.

Fox News' Wendell Goler contributed to this report.