But he pointed out that recent investigations have found that scientists' work was not compromised.
"I think it's really a lot of smoke but no fire," he said.
A panel convened by the British House of Commons to investigate the e-mails of Professor Phil Jones and his colleagues at the Climatic Research Unit of the University of East Anglia (CRU) found that the science was strong.
"Within our limited inquiry and the evidence we took, the scientific reputation of Professor Jones and CRU remains intact," the report said. "We have found no reason in this unfortunate episode to challenge the scientific consensus as expressed by [Prof. John Beddington, Chief Scientific Adviser to the British government], that 'global warming is happening [and] that it is induced by human activity.'"
The report did, however, criticize the scientists for not being more open about their work.
Another independent investigation conducted by the University of East Anglia also found no evidence of "deliberate scientific malpractice" in the group's work.