In any debate over climate change, conventional wisdom holds that there is no reflex more absurd than invoking the local weather.
And yet this year’s wild weather fluctuations seem to have motivated people on both sides of the issue to stick a finger in the air and declare the matter resolved — in their favor.
“Within psychology, it’s called motivated reasoning, or the confirmation bias,” explained Anthony Leiserowitz, the director of the Project on Climate Change Communication at Yale University’s School of Forestry and Environmental Studies. “People are looking for evidence of any kind that validates or reinforces or justifies what they already believe.”
Last February, for example, as a freak winter storm paralyzed much of the East Coast, relatives of Senator James M. Inhofe, the Oklahoma Republican who is a skeptic of climate change, came to Washington and erected an igloo.
They topped it with a cheeky sign asking passers-by to “Honk if you ♥ global warming.” Another sign, added later, christened the ice dome “Al Gore’s new home.”
Environmentalists roundly criticized the stunt for relying on a fact as lonely as a snowstorm. “Weather is our day-to-day experience, while climate is more static, describing a region’s typical weather conditions as established over periods of time,” explained Adrianna Quintero, a senior attorney with the Natural Resources Defense Council, in a blog post scolding the deniers.
Now, with record heat searing much of the planet from Minnesota to Moscow, people long concerned with global warming seem to be pointing out the window themselves.
“As Washington, D.C., wilts in the global heat wave gripping the planet, the Democratic leadership in the Senate has abandoned the effort to cap global warming pollution for the foreseeable future,” wrote Brad Johnson at the progressive Wonk Room blog, part of the Center for American Progress.
Of course, it’s probably not surprising that outspoken partisans sometimes use the weather as a rhetorical tool, but researchers are also learning that many less certain people unwittingly take note of temperatures, too.
Mr. Leiserowitz has identified what he and fellow researchers call “Global Warming’s Six Americas” — from people who are “alarmed,” “concerned” or merely “cautious” on climate change, to those who are “disengaged,” “doubtful” or wholly “dismissive.”
For people at either extreme — that is, those alarmed by or dismissive of climate change — the local weather isn’t going to have much influence, although they may use it conveniently to drive home a point.
But for those in the mushy middle — about a third of the overall population — the local weather, rightly or wrongly, influences their thoughts on the topic, often subconsciously.
That idea is reinforced by another study under review at the journal Psychological Science. Researchers at Columbia University found a high correlation between a participant’s stance on global warming and how he perceived the outdoor temperature on the day he was asked about it. Study subjects were also more likely to say they would donate to a global warming charity on days they perceived to be unusually warm.
For Eric J. Johnson, the director of the Center for Decision Sciences at Columbia Business School and a co-author of the study, the findings highlight the pitfalls of policymaking by poll, given that opinions on such a complex issue appear susceptible to highly impertinent data.
“It’s like assessing how the economy is doing by looking at the change in your pocket,” Mr. Johnson said. “It’s relevant, but not that relevant.”
There is a not-insignificant caveat: Those pointing to hot weather as evidence of global warming are, in the broadest sense, more likely to be right. Scientists at the National Center for Atmospheric Research in Colorado demonstrated last year that record high temperatures have occurred twice as often as record lows over the last decade.
That’s in keeping with most models of global warming, which predict not a steady climb in temperature, but higher average readings over time — and more record-breaking peaks than valleys.
Whether that makes it fair to consciously lean on the weather when it’s convenient is an open question — though it appears hard for either side to resist.
But he apparently had some help in making his point.
We “went in the night before and opened all the windows, I will admit, right? So that the air-conditioning wasn’t working inside the room,” recalled Timothy Wirth, the former Democratic senator from Colorado, in an interview with “Frontline” in 2007.
Mr. Hansen was “wiping his brow at the witness table,” Mr. Wirth said, “and giving this remarkable testimony.”