Partially-submerged cars bring attention to the potential of flooding caused by global warming. (Photo: Akuppa)

Poll shows drop in concern about climate change in U.S., but waning concern may not be as sharp as it appears.

As world leaders descend on Copenhagen for the final days of the UN's COP15 climate summit, results of a new Zogby poll released today suggest that almost half of Americans--49%--say they are only slightly or not at all concerned about climate change, up from 39% in 2007. Conversely, the poll suggests that 35% of Americans are somewhat or highly concerned about global warming and climate change, down from 48% in 2007.

The results of the Zogby poll confirm the conclusions of other polls that American concern for climate change is declining while global concern is on the uptick. And the figures for Republicans are also in line with figures about Republican leadership; nearly three-quarters of U.S. Senate Republicans doubt the human causes of global warming.

But before we accept the results of the Zogby poll at face value, there are a couple methodological issues that should be raised.

December or June?

The 2007 survey was conducted between June 15-18 and polled 8,300 adults nationwide, producing a margin of error of 1.1%.  But in 2009, the survey was conducted between December 8-10 and polled only of 3,072 adults nationwide, producing a margin of error of 1.8%. Other than the fact that it is generally warmer in North America in June than it is in December, June 2007 was 1.4° F above the 20th century average of 69.3° F.

Final temperature data for December is obviously not available yet but I'm pretty sure it was colder in December of 2009 than it was in June of 2007, or any year for that matter, just about everywhere in the U.S. While fluctuations in temperatures are poor indicators of long-term warming or cooling climate trends, they can definitely influence the average person's opinion--consciously or subconsciously--on global temperature trends, even if empirical data show otherwise.

Contaminating the sample?

Finally, the samples taken in the two polls also cannot be removed from the larger political context in which they were taken.  Considering that some news outlets began reporting on 'Climategate' as the 'final nail in the coffin of anthropogenic global warming', the timing of the poll--just two weeks after the story of the controversial e-mails broke--snapped an image of public opinion when lots of claims are being made about the validity of the science or the data contained in the IPCC report.

In theory, public opinion is designed to capture the mood after such events, but I would argue that a more accurate portrayal of the impact of the Climategate e-mails cannot be made until the initial spark of its interest has expired.

Gauging public opinion is often like hitting a moving target and if we want to really understand the mood of the people, pollsters are better off trying to hit the target when it has stabilized after being jolted by what political scientists like to call an,  'external perturbation.'

So when you hear these numbers, or any other public opinion statistics for that matter, trumpeted around, keep in mind that the changing picture Zogby paints may not be as stark as it first appears.

Numbers don't always speak for themselves.

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Image credit: Akuppa via flickr/CC 2.0