 Coleman spoke out as a "rejectionis[t]" of global warming in 2007 after watching NBC's "Green is Universal" week, where the studio lights were cut for portions of "Sunday Night Football's" pre-game and half-time shows.In a 2015 open letter to the Intergovernmental Panel on Climate Change, he argued that a direct correlation between rising levels of atmospheric CO2 and rising temperatures has not been shown to exist.He has called global warming the "greatest scam in history" and made numerous false or misleading claims about climate science.