There was no scientific malpractice at the University of East Anglia's Climatic Research Unit, which was at the centre of the "Climategate" affair.
This is according to an independent panel chaired by Lord Oxburgh, which was convened to examine the research published by the unit.
It began its review after e-mails from CRU scientists were published online.
The panel said it would be helpful for researchers to work more closely with professional statisticians in future.
This would ensure the best methods were used when analysing the complex and often "messy" data on climate, the report said.
"We cannot help remarking that it is very surprising that research in an area that depends so heavily on statistical methods has not been carried out in close collaboration with professional statisticians," the panel remarked in its conclusions.
The e-mails issue came to light in November last year, when hundreds of messages between CRU scientists and their peers around the world were posted on the internet, along with other documents.
Critics said that the e-mail exchanges revealed an attempt by the researchers involved to manipulate data.
But a recent House of Commons Science and Technology Committee report into the e-mails concluded that the scientists involved had no intention to deceive.
And Lord Oxburgh said that he hoped these "resounding affirmations" of the unit's scientific practice would put those suspicions to bed.
He stated: "We found absolutely no evidence of any impropriety whatsoever. That doesn't mean that we agreed with all of their conclusions, but these people were doing their jobs honestly."
The chair has been challenged over his other interests. Lord Oxburgh is currently president of the Carbon Capture and Storage Association and chairman of wind energy firm Falck Renewables.
Critics say clean energy companies would benefit from policies to tackle climate change. But Lord Oxburgh insists the panel did not have a pre-conceived view.
The panel included Professor David Hand, president of the Royal Statistical Society, who had been examining the way CRU used statistical methodology to develop an average annual global temperature.
Climate sceptics have argued that CRU's statistical methods were inadequate.
Professor Hand said that the CRU scientists did not use "the best statistical tools for their studies" but that this had made not significant difference to their conclusions.
Dealing with uncertainty
Professor Hand pointed out that the translation of "messy data" into clear facts had caused problems.
But he said that the CRU were "to be commended for how they dealt with the data," adding that, in their research papers, they were very open about the uncertainty in the numbers.
It is straightforward to get a measurement precise in space and time from an individual weather station - albeit with uncertainties attached.
But some countries have many weather stations, while others have very few, and there are sizeable areas of the Earth with no surface measurements at all.
"Unfortunately," Professor Hand said, "when this research is [republished and] popularised, those caveats tend to be forgotten."
The panel noted that the Intergovernmental Panel on Climate Change (IPCC) was one of the organisations that had "oversimplified" the CRU data it used in its publications.
They said the IPCC and others had neglected to highlight the discrepancy between direct and "proxy" measurements, such as the tree ring data often used to reconstruct past temperature changes.
Professor Hand added that CRU had been "a little naïve" in not working more closely with statisticians.
The report stated: "There would be mutual benefit if there were closer collaboration and interaction between CRU and a much wider scientific group outside the relatively small international circle of temperature specialists."
UEA's vice chancellor Edward Acton said he welcomed the report.
"It is especially important that, despite a deluge of allegations and smears against the CRU, this independent group of utterly reputable scientists have concluded that there was no evidence of any scientific malpractice," he said.
Dr Benny Peiser, director of the Global Warming Policy Foundation, criticised the panel for producing a report that was "not even-handed" and appeared to be the product of a "rushed job".
He said: "This has produced a very superficial report. The panel should have taken more time to come to more balanced and trustworthy conclusions.
"They should have heard evidence from critical researchers who have been working in the same field for many years."
But Lord Oxburgh said that the seriousness of the allegations being investigated made it crucial that the panel publish their findings "as quickly as possible".
He explained: "We read 11 key [CRU] publications spreading back over 20 years and a large number of others. We then spent 15 person days interviewing the scientists at UEA.
"I don't know what more we could have done and we came to a unanimous conclusion."