Michael Mann, a Pennsylvania climate-change researcher caught in the flap surrounding e-mails hacked from a British university server, was cleared of wrongdoing by a U.S. agency that promotes science.
Finding no "evidence of research misconduct," the Arlington, Va.-based National Science Foundation closed its inquiry into Mann, according to an Aug. 15 report from its inspector general. In February, Pennsylvania State University, where Mann is a professor of meteorology, exonerated him of suppressing or falsifying data, deleting e-mails, and misusing privileged information.
Skeptics of climate change pointed to the stolen e-mails, which surfaced in blogs in 2009, as proof that researchers conspired to suppress studies questioning the link between warming and human activity. Last week, Texas Gov. Rick Perry, who is seeking the Republican nomination for president, repeated the charge that scientists have "manipulated" data on climate change.
"It was a pretty definitive finding" that the charges "swirling around for over a year" were baseless, Mann said in an interview.
The report confirms findings from the U.S. National Oceanic and Atmospheric Administration's inspector general and a separate panel of seven scientists based at universities in Britain, the United States, and Switzerland.
The inquiries focused on the University of East Anglia's climate-research unit, which stored the poached e-mails on its computer server. The university's work contributed to some of the key findings of the United Nations Intergovernmental Panel on Climate Change, which has issued reports that blame rising temperatures on human activity.
E-mails to and from Mann were in the pilfered cache. One message discussing his work spoke of a "trick" to "hide the decline" and others suggested deleting correspondence.
Mann was lead author of the first reconstruction of North American warming going back 1,000 years, which showed recent temperatures increasing sharply. The 1998 findings have been confirmed by several studies, Mann said.