More than 400 people, many of them climate-control supporters, arrived in the Danish capital aboard a special train Sunday, after traversing much of Western Europe en route to a historic meeting to replace the Kyoto Protocol, which expires in 2012.

Representatives from nearly 200 countries, including Prime Minister Stephen Harper, are expected to attend the 12-day summit, which starts Monday.

About 15,000 people in total are to attend the event. Many will arrive by train from European cities, in an effort to mitigate the environmental impact of holding the conference. Others will fly in from continents around the globe.

They are expected to aim towards cutting emissions that scientists say cause global warming. They will also come to an agreement on whether rich countries should pay to help poor countries fight climate change.

The event is being held as controversy rages about climate-change emails stolen from a research lab at the University of East Anglia in England.

The emails in question have been dubbed "ClimateGate." Climate-change skeptics claim they show that scientists have tried to hide data that diminishes or contradicts the impact of global warming, and that scientists were highly dismissive of critics who questioned their findings.

But the scientists who wrote the emails say the release is a smear campaign, and that the content of the emails are being misinterpreted and slanted.

The head of Greenpeace Canada said the timing of the release was "politically motivated" to distract people ahead of the Copenhagen summit.

"People are going to look at the solid body of scientific evidence that is out there and realize that this is really a distraction and a politically motivated one," said Bruce Cox, the Executive Director of Greenpeace Canada.

"I think there are probably vested interests out there that knew that this would harshly -- I don't want to say derail -- but would act as a distraction," he said in an interview with CTV News Channel Sunday.

"Clearly it's a huge distraction from what needs to be done in Copenhagen."

He made the comments ahead of the Copenhagen, Denmark climate change summit, which begins Monday. World leaders will discuss how to reduce emissions that are believed to contribute to climate change.

Correspondence 'looks very bad'

The United Nations' top climate official acknowledged Sunday that the release of the emails has damaged the public's perception of the credibility of the scientific community.

Yvo de Boer said the emails fueled suspicion among those who think science is exaggerated to alarm the world over climate change.

"I think a lot of people are skeptical about this issue in any case," de Boer told The Associated Press. "And then when they have the feeling ... that scientists are manipulating information in a certain direction then of course it causes concern in a number of people to say 'you see I told you so, this is not a real issue."'

"This correspondence looks very bad," he added.

However, he defended climate change research, which has been reviewed by about 2,500 scientists, saying he thinks "this is about the most credible piece of science that there is out there."

Cox said he believes people will continue to look at climate change research in the same way they always have.

"It doesn't really change the wide body of scientific information out there and it doesn't change what is obvious to everybody: our climate is changing," he said.

The email hackers stole more than 1,000 emails and other documents from the leading climate change research unit at the university.

The director of the research institute, Phil Jones, stepped down this week as police launched a criminal investigation surrounding the breach. The United Nations announced Friday that it would launch its own investigation into the emails.

On Thursday, the university announced that it would investigate whether any data had been altered.

De Boer said he thinks the Copenhagen summit will make progress because some countries have already made tangible commitments.

One agreement was set by the Commonwealth nations -- including Canada -- who last week agreed to contribute to a $10 billion fund to help countries that are only a few metres above sea level and therefore at most risk from any rise in levels due to climate change.

With files from The Associated Press