Closing a four-month investigation, a Pennsylvania State University committee said Thursday that there is "no substance" to allegations that the prominent climate scientist Michael E. Mann had deviated from accepted scholarly practices in his research on global warming.
The committee's unanimous 19-page report ends one of a series of investigations growing out of last year's "Climategate" controversy, in which e-mail messages stolen from servers at the University of East Anglia were used to cast doubt on the findings and integrity of climate-change scientists. None of the investigations has turned up evidence of wrongdoing to date.
The Penn State investigation was prompted, the university said, by complaints the university received about Mr. Mann after the theft from "alumni, federal and state politicians, and others, many of whom had had no relationship with Penn State."
Mr. Mann, a professor of meteorology at Penn State since 2005, is best known to the public as the co-creator of the 2001 "hockey stick" graph showing that global temperatures, after remaining stable for several hundred years, rose sharply in the 20th century. He has been a frequent target of those who question whether global warming is real, and is now the focus of an investigation by Virginia's attorney general, Kenneth T. Cuccinelli II, into whether Mr. Mann relied on manipulated data to seek grants while he was a faculty member at the University of Virginia.
In January, a different Penn State committee cleared Mr. Mann of allegations that he had suppressed or falsified data, deleted or concealed information, or misused privileged information. But that committee recommended that a separate panel review whether Mr. Mann had "seriously deviated from accepted practices within the academic community for proposing, conducting, or reporting research or other scholarly activities."
The panel's report on Thursday said he did not. It did say, though, that he had been "careless" about showing other scholars' unpublished research to third parties without permission.
On his Web site, Mr. Mann posted a message saying he was pleased by the report, which he said, "should finally put to rest the baseless allegations against me and my research."