His research with UConn political science graduate student Salil Benegal found that popular alternative explanations -- partisan politics on the issue, accusations of biased media coverage, and weather fluctuations -- could not explain the suddenness and timing of the changing opinions.
Many people believe the solution to global warming is suppressing economic activity, Scruggs says, but that's an unpopular view when the economy is struggling. "So it's easier for people to disbelieve in climate change than to accept that it is real, but little should be done about it right now," he says.
Scruggs and Benegal published their findings online in the journal Global Environmental Change on Feb. 24.
The study relies primarily on information from numerous national and international public opinion surveys dating to the late 1980s.
The researchers found stark declines in the public's belief in global warming in the late 2000s. In 2008, for example, the Gallup poll reported 60 to 65 percent of people agreed with statements that global warming is imminent, is not exaggerated and is agreed upon by scientists as a valid theory. By 2010, those numbers had dropped to about 50 percent.
The authors also found a strong relationship between jobs and people's prioritization of climate change. When the unemployment rate was 4.5 percent, an average 60 percent of people surveyed said climate change had already started. But when the jobless rate reached 10 percent, that number dropped to about 50 percent.
Scruggs says the trend also held true among survey respondents across political parties.
The authors did find that if people had experienced a recent change in short-term weather, they were more likely to believe that climate is changing over the long term. But when these effects were controlled, the economy mattered more than the weather, Scruggs says.
Their research found the same skepticism during tough economic times in European countries, despite what some see as a stronger overall pro-climate ethos there.
The researchers speculate that cognitive dissonance, which occurs when people experience conflicting thoughts and behaviors, could explain the pattern. Many people view economic growth and environmental protection to be in conflict, so admitting that climate change is real but should be ignored in favor of economic growth leads to an internal philosophical clash.