The survey, which queried more than 1,000 adults across the country about global warming and extreme weather, discovered roughly two-thirds of Americans believe global warming is linked to several of the extreme weather events of 2011 and the recent mild winter.
Predictably, this news has drawn the full spectrum of reactions.
Michael Lemonick, science writer at Climate Central, framed the survey results as a positive development in science communication and public awareness. He said the human brain is “a powerful pattern-recognition machine” concluding: “the recognition that climate change and extreme weather are indeed related is a significant step forward in an area where too much doubt and confusion have reigned for too long.”
Roger Pielke, Jr., professor of environmental science at University of Colorado, sharply criticized a New York Times article about the study for “[celebrating] the fact that many Americans fail to understand how human-caused climate change may be related to recent extreme events.”
If you compare the survey results to current scientific understanding of the link between global warming and extreme weather - it seems the opinions of the U.S. public are generally in step with our state of knowledge, but perhaps oversimplied. So both Pielke’s and Lemonick’s perspectives have merit.
Consider the following findings from a recent Intergovernmental Panel on Climate Change (IPCC) report on climate change and extreme weather, pertaining to links to increases in warm weather:
* It is likely (66-100% chance) an overall increase in the number of warm days and nights have occurred at the continental scale in North America
* It is likely (66-100% chance) that [manmade] influences have led to warming of extreme daily minimum and maximum temperatures at the global scale.
Now consider that in the survey:
* 72% of respondents strongly or somewhat agreed global warming made the unusually warm winter worse
* 70% of respondents strongly or somewhat agreed global warming made the record high temperatures in summer 2011 worse
Notwithstanding linking warm weather and climate change at local scales is more difficult than global scales, these results show the public “gets” the scientifically-solid notion that global warming should increase the odds of warm weather.
On climate change and precipitations trends, the IPCC report was a little more nuanced, especially with respect to precipitation changes at the local scale and connections to human influences. It found:
* There have been statistically significant trends in the number of heavy precipitation events in some regions. It is likely (66-100% chance) that more of these regions have experienced increases than decreases, although there are strong regional and subregional variations in these trends.
* There is medium confidence that some regions of the world have experienced more intense and longer droughts, in particular in southern Europe and West Africa, but in some regions droughts have become less frequent, less intense, or shorter, for example, in central North America and northwestern Australia.
* There is medium confidence that anthropogenic influences have contributed to intensification of extreme precipitation at the global scale.
Consistent with IPCC’s more tentative statements, the public’s acceptance of connections between extreme precipitation and global warming were not as strong. In the survey:
* 61% of respondents strongly or somewhat agreed record snowfall in the U.S. was linked to global warming.
* 63% of respondents strongly or somewhat agreed the Mississippi River floods in the spring of 2011 were linked to global warming
* 69% of respondents strongly or somewhat agreed the drought in Texas and Oklahoma was linked to global warming.
* 59% of respondents strongly or somewhat agreed the Hurricane Irene was made worse due to global warming.
You could make the arguments the above percentages are too high given uncertainties in linking global warming and individual winter storms/floods/droughts/hurricanes, especially at the local scale. The IPCC, in fact, specifically cautions “Attribution of single extreme events to anthropogenic climate change is challenging.”
On the other hand, the overall concept that, with global warming, dry weather trends drier and wet weather trends wetter is well-established, and these results would indicate the public appreciates that.
Furthermore, survey respondents weren’t given the option of more nuanced responses. They could either strongly agree, somewhat agree or the reverse.
Americans, thus, correctly accept the idea global warming should make the weather warmer and precipitation events a bit more extreme. They may overreach in connecting individual weather events to climate change, but these connections are complex and it’s probably not reasonable to expect most people to unravel all of the intricacies.