CNN anchor Carol Costello recently asked Bill Nye “The Science Guy” if he is “disappointed” that climate change is largely ignored in American political discourse. Nye responded: “Well if I'm disappointed, everybody, it's in you guys.” And with good reason: CNN rarely mentions climate change, even while reporting on its consequences -- as a new Media Matters study shows.

Scientists warn that human-induced climate change will increase the frequency and severity of extreme heat events like last month's historic heat wave. But a Media Matters analysis finds that the major television outlets largely overlooked climate change in their coverage of record-breaking July heat. Overall, only 9% of heat wave coverage mentioned climate change. CNN's coverage was among the worst: in 111 segments, only four mentioned climate change.

This is not the first time CNN has failed to connect the dots between climate change and related extreme weather events. Media Matters reported last month that although seven out of nine fire experts contacted agreed that journalists should explain how climate change increases the risk of wildfires in the Western U.S., CNN mentioned climate change in only 1% of Western wildfire coverage.

CNN has also turned a blind eye to the related threat of ocean acidification, another consequence of rising carbon dioxide emissions. In 2011 and the first half of 2012, CNN covered ocean acidification once. During the same period, the network covered the Kardashians more than 250 times.

The vast majority of scientists say the public should be worried about the threat manmade climate change poses to human well-being and the environment. If politicians are ignoring their warnings, the media's role is to challenge them -- as Nye rightly noted. Now that CNN's Candy Crowley has been selected to moderate a presidential debate in October, will CNN press the candidates on what they plan to do to address climate change?