A powerful nor’easter cloaked the Mid-Atlantic and Northeastern United States in white on the first day of Northern Hemisphere winter in 2009. Especially cold or hot weather can -- at least temporarily -- outweigh more relevant global climate data in the minds of most people when they form opinions about global warming.
Last week's polar vortex weather event wasn't only hard on fingers, toes and heating bills. It also overpowered the ability of most people to make sound judgments about climate change, in the same way that heat waves do, according to a new study published in the Jan. 11 issue of the journal Nature Climate Change.
Researchers have known for some time that the acceptance of climate change depends on the day most people are asked. During unusually hot weather, people tend to accept global warming, and they swing against it during cold events.
“While a number of studies have looked at the relationship between daily temperature and global warming judgments or opinions, very few have explored the psychology that underlies the effect,” said Lisa Zaval, a graduate student in psychology at Columbia University and lead author of the new research that begins to dig deeper.
Zaval and her colleagues looked at five recent studies on the effects of warm weather on climate change opinions and found evidence for something called attribute substitution. That's where a person forms their opinions using less relevant, but more readily available, information (like today's temperature), rather than more diagnostic, but less accessible, information (like global climate change patterns). There is every reason to expect that it works the same way with cold snaps, she said.
“Across studies, our data suggest that perceiving today’s local temperature to be colder than usual can lead to decreased belief in and reduced concern about global warming,” Zaval explained. “It seems likely that attribute substitution plays a role for unusually cold temperatures, as well as unusually warm temperatures.”
They also found that present extreme temperatures can reinforce our memories of past similar events. In other words, an especially hot day today can cause us to overestimate the frequency of similar past events, which can further increase our belief in global warming – at least until the weather changes.
For scientists and educators trying to get people to understand climate science, the conclusion seems discouraging, since it's hard to make global climate information as easily available as looking out the window, and it's hard to get policy makers to do the right thing when public opinion wavers so much. But this is where global warming itself might help, said geographer Peter Howe, who studies related matters at Utah State University.
“I'm a bit more optimistic,” said Howe. “We're going to see more extreme heat events in the future and people will learn through their experience.”
In the meantime, one thing that might be helpful, Howe suggested, is for broadcast meteorologists to put more climate information into their daily weather reports, so that they're reporting on not just the short-term, but putting it into the context of long-term patterns.
“We've mostly solved the physical science of climate change,” Howe said, referring to the vast amount of research showing that global warming is real and caused by human burning of fossil fuels. “Now we are working on the social puzzle.”