A few years back, the US public's acceptance of conclusions reached by climate scientists took a dramatic drop. It's only now beginning to recover. Not a lot has changed about the science during that time, raising questions about what's driving the ups and downs in the polls. Studies have found correlations with the weather and a role for political leaders in driving these changes, but a new study suggests some of that is misplaced. Instead, its authors come to a conclusion we've heard before: it's the economy, stupid.

The authors use polling data from a variety of sources, which creates a bit of a challenge. Not all polls ask questions that address the same things. For example, one of the studies we linked above asked about the public's acceptance of a basic fact: has our planet been getting warmer over the past few decades? In contrast, one of the polls used here assessed feelings about climate change by asking its participants whether they felt the media "exaggerate the seriousness of global warming."

Still, there are ways to convert these specific sentiments into a generalized sense about the seriousness of climate change. Plus, the variety of polls provide some distinct advantages. For example, this survey provides a valuable outgroup to the US population, in that a number of surveys cover all the nations of the European Union. In addition, several of the polls (those performed by the Pew) include ZIP code information, allowing the authors to compare polling trends with record high and low temperatures in the nearby area.

As with another recent survey, they do end up seeing a correlation between acceptance of climate change and the weather. However, the correlation with local weather is rather weak. Instead, the authors found a stronger correlation with the global mean temperature. That's somewhat surprising. Most years, the global mean isn't especially well covered by the press, which suggests this correlation might be a bit spurious. (If we accept the economy is an influence, then the correlation will be very difficult to tease apart. Especially considering the coldest global temperature of the last decade happened to correspond to the onset of job losses in the US.)

In any case, the poll numbers indicate there are some things that we probably can't blame them on. For example, acceptance started to drop prior to the Copenhagen climate conference and the release of the e-mails stolen from the University of East Anglia. Both of these may have been big news among people who care passionately about climate change, but they came too late to explain the public's reduced acceptance of the science.

Based on their statistical analysis, the authors conclude the economy is the strongest influence on the public's acceptance of climate science. This held when the authors analyzed things separately in each US state based on its local unemployment rate. The effect showed up in European countries, as well. In Gallup polls, this correlation holds all the way back to 1989, when the current string of unusually warm years began. Overall, the authors found unemployment had an effect that was over three times stronger than either the local weather or skeptical coverage of climate in the media.

Put in other terms, each time the local unemployment increased by a point, that state saw its average citizen's probability of accepting climate change drop by over 10 percent.

Similar things were seen in Europe: "A one point increase in national unemployment is associated with a 2.5 point decline in the percentage saying that warming is a serious issue, and almost a one point increase in the percentage of the country saying that warming is exaggerated or saying that it is simultaneously not serious, exaggerated, and not due to CO2 emissions."

The authors note this is in keeping with past findings, which showed people generally value environmental protection less when unemployment is an issue. They suggest this is an attempt to reduce cognitive dissonance: as people increase their concern for the economy, they drop their support for anything that's perceived as getting in the way of that. Which might help explain one of the earlier findings, that political figures have an influence on the public's perception of the climate. In the US at least, there's no shortage of politicians who have been willing to attack environmental regulations as damaging to the economy.

(Of course, the politicians may also be responsive to the public's beliefs. As the authors note sardonically, "While the earth’s climate may not react to what people think about the climate, elected politicians often do.")

Even they are stumped, however, that the public doesn't only change its views on the importance of a policy response to climate change. Instead, it seems to start questioning reality itself. "What is more puzzling is not that people’s priorities shift with the economic conditions, but that their beliefs about basic climate facts and their trust in climate science also appear to change," the authors note.

Global Environmental Change, 2012. DOI: 10.1016/j.gloenvcha.2012.01.002 (About DOIs).