U.S. climate scientist Michael Mann must pay National Review more than $500,000 in legal fees after 13 years of suing the outlet for defamation

Michael Mann will have to pay National Review more than $500,000 for legal expenses nearly 13 years after their legal battle began.

Mann sued National Review in 2012 after conservative commentator Mark Steyn criticized Mann in a post to National Review’s website.

Mann is one of the creators of the 1998 “hockey stick” climate model, which combines a number of different proxies for climate change into a single model.