A tractor prepares a field under wind turbines at the Spearville Wind Energy Facility near Spearville, Kan. Wind power has been pushed as a way to fight climate change. ((Orlin Wagner/Associated Press))

Climate change scientists are on the defensive after hackers broke into a server of a British climate research centre over the weekend and posted hundreds of private emails that appear to show scientists have overstated the threat of man-made global warming.

On Saturday, the University of East Anglia, in eastern England, said in a statement the hackers had entered the server and stolen data at its Climatic Research Unit, a leading global research centre on climate change.

The hackers reportedly stole more than a decade of correspondence between leading British and U.S. scientists, and posted about 1,000 emails and 3,000 documents on websites.

Skeptics of climate science have seized on the documents — at least some of which have been confirmed as authentic — as evidence that some scientists have overstated the case for global warming and have attempted to manipulate data.

But researchers working with the Intergovernmental Panel on Climate Change have dismissed the posting of documents as an attempt to derail discussions on dealing with global warming in advance of an upcoming global summit in Copenhagen.

Kevin Trenberth, head of the climate analysis section of the U.S. National Center for Atmospheric Research in Boulder, Colo., said the hackers were selective in choosing documents they believed could be used to make the scientists look bad.

"It comes down to politics at sort of all levels, and some of it's nasty and some of it is trying to destroy the message or even kill the messenger so to speak," said Trenberth.

In one leaked email, the East Anglia research centre's director Phil Jones wrote that he had just completed a "trick of adding in the real temps to each series for the last 20 years (i.e. from 1981 onwards) and from 1961" in order to "hide the decline," according to a leaked email, which the author confirmed was genuine.

Jones denied manipulating evidence and insisted his comment had been taken out of context.

"The word 'trick' was used here colloquially, as in a clever thing to do. It is ludicrous to suggest that it refers to anything untoward," he said in a statement Saturday.

Rajendra Pachauri, the chair of the UN's Intergovernmental Panel on Climate Change, told Reuters the communications posted online "in no way damages the credibility" of the panel's working group's 2007 findings that global warming is "very likely" caused by man-made greenhouse gas emissions.

With files from The Associated Press