Professor David Hand said that the research â€“ led by US scientist Michael Mann â€“ would have shown less dramatic results if more reliable techniques had been used to analyse the data.
Prof Hand was among a group of experts charged with investigating the “climategate” email scandal that engulfed the University of East Anglia’s Climatic Research Unit (CRU) last year.
Sceptics claimed that the hacked messages showed scientists were manipulating data to support a theory of man-made global warming.
However the review, led by Lord Oxburgh into the research carried out by the centre, found no evidence of ”deliberate scientific malpractice”.
Lord Oxburgh said the scientists at the research unit arrived at their conclusions ”honestly and sensibly”.
But the reviewers found that the scientists could have used better statistical methods in analysing some of their data, although it was unlikely to have made much difference to their results.
That was not the case with some previous climate change reports, where “inappropriate methods” had exaggerated the global warming phenomenon.
Prof Hand singled out a 1998 paper by Prof Mann of Pennsylvania State University, a constant target for climate change sceptics, as an example of this.