Throughout the recent record-breaking heat wave that affected millions across the United States, major broadcast TV networks overwhelmingly failed to report on the links between climate change and extreme heat. Over a two-week period from late June to early July, ABC, CBS, and NBC aired a combined 127 segments or weathercasts that discussed the heat wave, but only one segment, on CBS This Morning, mentioned climate change.

The recent heat wave was record-breaking and deadly

From the last week of June into the second week of July, an intense heat wave moved across the U.S., going from the eastern and central parts of the country to the West Coast. A large area of high atmospheric pressure helped to create a massive and powerful heat dome, which migrated from New England to southern California. The heat wave brought record-breaking temperatures -- during its first week, 227 U.S. records were broken for highest temperature for particular days, and during the second week, at least six locations in southern California alone saw record-breaking highs. The heat wave killed at least five people in the U.S. and up to 70 people in Quebec, Canada.

Climate change is exacerbating both the frequency and intensity of heat waves

There is overwhelming scientific evidence that human-induced climate change is exacerbating both the frequency and intensity of heat waves. Heat domes like the one that caused this recent heat wave are becoming more intense and more common, scientists have found. UCLA climate scientist Daniel Swain, who has studied extreme weather patterns in California, said recent heat in California was unusual. “The overall trend over decades to more intense and more frequent heat waves is definitely a signal of global warming,” he told The New York Times. And according to Jeff Masters, director of meteorology for Weather Underground, this recent heat wave was “the kind of thing you expect to see on a warming planet,” making it “easier to set a heat record.”

Recent studies also reinforce this point. In March 2018, an analysis of heat wave patterns published in Nature Climate Change concluded that climate change will overtake natural variability as the main cause of heat waves in both the western U.S. and Great Lakes region by the 2030s. Nature Climate Change also published a study last summer that detailed how heat waves will occur more frequently in the future due to climate change. Camilo Mora, associate professor at the University of Hawaii at Manoa and lead author of the 2017 study, said, “Many people around the world are already paying the ultimate price of heat waves, and while models suggest that this is likely to continue to be bad, it could be much worse if emissions are not considerably reduced.”

Broadcast networks almost completely ignored the links between climate change and heat waves

Media Matters analyzed morning and nightly news coverage of the heat wave on ABC, CBS, and NBC, as well as on PBS NewsHour, over a 14-day period from June 27 through July 10, covering the entire duration of the heat wave.

Neither ABC nor NBC mentioned that climate change influences heat waves. There were 32 segments or weathercasts on ABC and 59 segments or weathercasts on NBC that discussed the heat wave. None of them mentioned the link between climate change and extremely high temperatures.

CBS aired one segment that discussed the connection between climate change and high heat. Out of 36 CBS segments that mentioned the heat wave, just one mentioned climate change. The July 3 episode of CBS This Morning featured a discussion with Lonnie Quinn, chief weathercaster for WCBS-TV in New York City, who stated that there is a “really good, strong understanding that there’s a correlation between climate change and extreme hot and extreme cold” and noted the significant increase since 1970 in the number of days above 100 degrees in Miami, FL, and Austin, TX.

PBS NewsHour aired two segments on the heat waves, one of which discussed climate change. In its July 7 NewsHour program, PBS devoted a segment to the heat wave and incorporated climate change into its reporting, noting, “Global temperatures reached extreme highs this past week, something scientists have been warning of as part of the effects of climate change.” The segment also noted that July is off to a record-breaking start in terms of high temperatures.

Broadcast TV news has a track record of neglecting climate change in its reporting on extreme weather

In 2017, news programs on ABC, CBS, and NBC severely undercovered climate change’s real-life impacts on people and climate change’s effects on extreme weather events, Media Matters found in its latest annual study of broadcast coverage. Over a two-week period during the height of hurricane season in 2017, neither ABC nor NBC aired a single segment on their morning, evening, or Sunday news shows that mentioned the link between climate change and hurricanes.

But there are positive trends in broadcast coverage. PBS continues to set the standard for quality news coverage of climate change, as it has in the past. And local meteorologists are increasingly incorporating discussions of climate change into their segments and forecasts. For example, on July 4 in Kansas City -- where there were two suspected heat-related deaths -- NBC affiliate KSHB discussed that climate change is expected to increase the number of extremely hot days in the future, using a dynamic map from climate science nonprofit Climate Central to make the point.

Methodology

Media Matters searched Nexis, iQ media, and SnapStream for national news broadcasts that included a segment about the heat wave, using the search terms (heat OR “heat wave” OR “heat waves” OR heatwave OR heatwaves OR temperature OR temperatures OR hot). A second search adding the term AND (“climate change” OR “global warming”) was used to identify any segments on the heat wave that mentioned climate change. We did not count teasers or rebroadcasts. Our analysis covered early morning news shows (ABC's America This Morning, CBS Morning News, and NBC's Early Today), morning news shows (ABC's Good Morning America, CBS This Morning, and NBC's Today), and nightly news programs (ABC World News Tonight, CBS Evening News, NBC Nightly News, and PBS NewsHour) from June 27 through July 10.