Allegations of research improprieties relating to leaked emails on global warming against a leading climate scientist have been dismissed by an internal inquiry.
But the Penn State University investigation recommended further examining one allegation regarding leaked emails about global warming.
Meteorology professor Michael Mann said he was pleased the inquiry results "found no evidence to support" four allegations against him.
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But in a report issued on Wednesday, Penn State said its inquiry could not make a "definitive finding" on one allegation of inappropriate research conduct, warranting further investigation.
Mann 'welcomes investigation'
Mann, long a target of criticism by skeptics of man-made global warming theories, said he welcomed the investigation, in hopes of removing lingering doubts.
A three-member committee has been looking into emails pertaining to Mann or his work since late November, when computer hackers obtained messages between US and British scientists from a British research centre.
The security breach at the Climatic Research Unit at the University of East Anglia leaked correspondence that critics have said proves scientists may have hidden evidence and overstated the case for man-made global warming.
The committee "could not make a definitive finding whether there exists any evidence to substantiate that Dr Mann did engage in, or participate in, directly or indirectly, any actions that deviated from accepted practices within the academic community for proposing, conducting, or reporting research or other scholarly activities," the report said.
Emails, articles reviewed
Besides 377 email messages, related journal articles and reports were also reviewed.
Five other faculty members will take part in the investigation phase looking into Mann's work, though it was unclear when that process would begin, school spokeswoman Lisa Powers said.
The report said three other allegations contained "no substance" and did not warrant further scrutiny, including whether Mann took part in suppressing or falsifying data; deleting or concealing emails, information or other data; or misusing privileged or confidential information available though his capacity as an academic scholar.
"Three of the four allegations have been dismissed completely," Mann said in a statement he issued on Wednesday.
"Even though no evidence to substantiate the fourth allegation was found, the university administrators thought it best to convene a separate committee of distinguished scientists to resolve any remaining questions about academic procedures.
"This is very much the vindication I expected since I am confident I have done nothing wrong."
