ClimateGate -- the controversy surrounding the leaked e-mails from the Climatic Research Unit at Britain's University of East Anglia -- means not only a credibility problem for some of the world's leading climate researchers. It also means a credibility problem for the U.N.'s Intergovernmental Panel on Climate Change, whose latest influential report, known as the AR-4, calls evidence of global warming "unequivocal."

These IPCC findings are largely based on the work of CRU, whose scientists are shown in the leaked emails to...