In 2011 the Frontier Centre for Public Policy think tank interviewed Timothy Ball and published his allegations about Mann and the CRU email controversy . Mann promptly sued for defamation . In June 2019 the Frontier Centre apologized for publishing , on its website and in letters , " untrue and disparaging accusations which impugned the character of Dr. Mann " . It said that Mann had " graciously accepted our apology and retraction " . This did not settle Mann 's claims against Ball , who remained a defendant
CRU email controversy
Climatic Research Unit email controversy
Michael E. Mann