The e-mails were posted on the internet last month
The UN's official panel on climate change has hit back at sceptics' claims that the case for human influence on global warming has been exaggerated.
The Intergovernmental Panel on Climate Change (IPCC) said it was "firmly" standing by findings that a rise in the use of greenhouse gases was a factor.
It was responding to a row over the reliability of data from East Anglia University's Climatic Research Unit
Leaked e-mail exchanges prompted claims that data had been manipulated.
Last month, hundreds of messages between scientists at the unit and their peers around the world were put on the internet along with other documents.
Some observers alleged one of the e-mails suggested head of the unit Professor Phil Jones wanted certain papers excluded from the UN's next major assessment of climate science.
Professor Jones, who denies this was his intention, has stood down from his post while an independent inquiry takes place.
In a statement, Professor Thomas Stocker and Professor Qin Dahe, co-chairmen of the IPCC's working group 1, condemned the act of posting the private e-mails on the internet, but avoided commenting on their content.
They went on to point to a key finding that states: "The warming in the climate system is unequivocal.
"[It] is based on measurements made by many independent institutions worldwide that demonstrate significant changes on land, in the atmosphere, the ocean and in the ice-covered areas of the Earth.
"Through further independent scientific work involving statistical methods and a range of different climate models, these changes have been detected as significant deviations from natural climate variability and have been attributed to the increase of greenhouse gases."
They added: "The body of evidence is the result of the careful and painstaking work of hundreds of scientists worldwide.
"The internal consistency from multiple lines of evidence strongly supports the work of the scientific community, including those individuals singled out in these e-mail exchanges."
The row comes ahead of the Copenhagen climate summit which starts on Monday.
Professor Jean-Pascal van Ypersele, vice-chairman of the IPCC, said it was no coincidence the information was released in the run-up to the summit.
He claimed unnamed conspirators could have paid for Russian hackers to break into the university computers to steal the e-mails.
He said the theft was a scandal and was "probably ordered" to disrupt the confidence negotiators have in the science.
Earlier, Climate Change Secretary Ed Miliband told the BBC he would be "very surprised" if there had been any wrongdoing on the part of the East Anglia University scientists.
"We're in a moment when the world is about to make some big political decisions," he said.
"And there will be people who don't want the world to make those big decisions and they are trying to use this in part to say somehow this is all in doubt and perhaps we should put the whole thing off.
"Well, I just think they're wrong about that."
Prime Minister Gordon Brown said the scientific evidence was "very clear" and called doubters a "flat Earth group".
He said: "There is an anti-change group. There is an anti-reform group. There is an anti-science group, there is a flat Earth group, if I may say so, over the scientific evidence for climate change."
'Open and transparent'
Meanwhile, the Met Office said it would publish all the data from weather stations worldwide, which it said proved climate change was caused by humans.
Its database is a main source of analysis for the IPCC.
It has written to 188 countries for permission to publish the material, dating back 160 years from more than 1,000 weather stations.
John Mitchell, head of climate science at the Met Office, said the evidence for man-made global warming was overwhelming - and the data would show that.
"So this is not an issue of whether we are confident or not in the figures for the trend in global warming, it's more about being open and transparent," he told the BBC.
The Met Office said it had already planned to publish the material long before the row and denied reports that government ministers had tried to block the publication.