News media coverage of global warming has often offered "balanced" accounts, quoting mainstream scientists and skeptics in the same story. Balanced accounts might be considered admirable efforts to abide by the journalistic norms of objectivity and fairness.

However, critics have noted that balanced reporting of this particular issue actually conveys a misleading portrait of the science of climate change, since scientists endorsing the mainstream view appear to outnumber skeptics. 

Our study explored the impact of including skeptical voices in news media coverage. In particular, we explored whether adding a skeptic to a story about a mainstream scientist's views or findings would reduce the number of people who perceive agreement among scientific experts on this issue and think global warming is a serious problem. 


Participants were invited to complete an Internet-based survey between January 15 and 18, 2009. The sample was divided randomly into five groups of equal size. Four of these groups each watched one of four short television news stories at the beginning of the study and answered general questions about it. The fifth group watched no television news story. All five groups then answered a set of questions measuring a variety of opinions about climate change.

Two of the news stories presented an interview with a mainstream scientist commenting either on the existence of global warming or its effects (we refer to these stories as "Existence Without Skeptic" and "Consequences Without Skeptic"). The other two news stories featured the same mainstream scientists followed by an interview with a skeptical scientist ("Existence With Skeptic" and "Consequences With Skeptic"). 

Video: Existence with skeptic

Video: Existence without skeptic

Video: Consequences with skeptic

Consequences without skeptic


Viewing an interview with a mainstream scientist only increased the number of people who believed that global warming has been happening and that humans have caused global warming. 

Adding the skeptic to the mainstream scientific message significantly reduced the number of people who endorsed a variety of beliefs and attitudes. Specifically, it made people: 

  • Less likely to believe that scientists agree that global warming has been happening Figure 1 (pdf)
  • Less certain that global warming has been happening Figure2 (pdf)
  • Less likely to ascribe high personal importance to the global warming issue 
  • Less likely to believe that global warming will be bad for people Figure 3 (pdf) 
  • Less likely to believe that global warming is a very serious issue 
  • Less likely to support more government action to deal with global warming Figure 4 (pdf)
  • Less likely to support a cap and trade system to limit greenhouse gas emissions Figure5 (pdf)

Figure 6 (pdf) illustrates the cognitive pathway by which the skeptic influenced policy preferences. Watching a skeptic decreased perceptions of consensus among scientific experts, and this decreased perception of consensus led respondents to be less supportive of government action in general and of cap and trade policy in particular. 


The news stories that respondents watched featured the views of only one skeptic and made no claims about the prevalence of such skeptical views. Nonetheless, respondents generalized from a single skeptic to scientists more generally, perceiving less agreement in the scientific community broadly. Our findings suggest that balanced news coverage may have been at least partly responsible for discrepancies between the American public and the scientific community on issues of climate change. 

Study summary, technical paper and figures used in the study.