Bias or balance?

Natural History, Nov, 2007 by Brendan Borrell

Scientific consensus that humans have caused global warming coalesced in about 1995. Yet for the next decade many Americans still believed that humankind's role in the emerging crisis was a matter of great debate. A new study lays some of the blame for that national misconception on the nightly TV news shows. To avoid the appearance of bias, they continued to air contrarian viewpoints long after the scientific debate was settled.

Maxwell T. Boykoff of the University of Oxford analyzed 143 news segments about climate change that were broadcast between 1995 and 2004 on programs ranging from the CBS Evening News to CNN's Wolf Blitzer Reports. Only 28 percent of the segments paralleled scientific opinion in portraying humans as the main cause of global warming, Boykoff discovered. Just a handful of segments went so far as to suggest that humans had a negligible effect on Earth's climate, but a full 70 percent gave roughly equal play to both sides of the debate.

Journalistic skepticism is useful, but Boykoff thinks that in this case, overrepresentation of minority opinions amplified uncertainty in viewers' minds. Fortunately, he notes, the accuracy of TV news--at least regarding humanity's role in global warming--has improved since 2004. (Climatic Change)