State of the Planet

News from the Columbia Climate School


Why Do We Run Hot and Cold on Climate Change?

A chart posted by Climate Central shows a declining trend for cold nights in New York City since 1970.

How cold was it last Tuesday? Cold enough to convince a lot of people global warming isn’t happening. Or at least confirm their belief that it isn’t.

But wait a minute: When the temperature hit 71 degrees in New York City on Dec, 22, that got a lot of people thinking that global warming IS happening.

Studies have shown that today’s temperature—our direct sensory experience—can affect our beliefs about climate. Poll numbers of those who believe in manmade global warming tend to shift upward when it gets hot, and downward when it gets cold.  Climate really is all about long-term trends—lots of data, some of it pretty messy. Neither the individual extremely warm day, nor the extremely cold day, are especially significant.

Nonetheless, people’s views on climate seem easily swayed, or in some cases manipulated, by daily weather. The onslaught of snarky, “I told you so” comments in the media and the blogosphere after last week’s deep freeze—from Rush Limbaugh ranting about a “polar vortex” conspiracy to Donald Trump calling climate change a hoax on the Fox News Channel—seem to confirm this.

In a study out today in Nature Climate Change, researchers from the Earth Institute’s Center for Research on Environmental Decisions drilled into what goes on in people’s minds when they respond to these smaller-scale stimuli. In a series of surveys, they found that people tend to latch onto the most accessible and immediate information—temperature or otherwise—that they are presented with, and this often trumps deeper knowledge.

In the surveys, the researchers looked at several factors that could influence how people perceive the climate—for instance, they tested 686 people on whether the wording of a question affected reactions on a particularly warm day. Did using “global warming” versus “climate change” make any difference? The answer: Not really.

In another survey, they gave some of 330 respondents information on the scientific distinction between local temperature and global climate change, and gave others in a control group information unrelated to climate. Did knowing more about how climate works change how that day’s weather affected the respondents’ views on climate? No again.

Then the researchers wanted to see if more accessible information—like today’s temperature—simply overrides less accessible information, such as the scientific explanations of global climate change.

They tried a “priming” exercise: In addition to asking about today’s temperature, they asked 300 participants to do a word puzzle that included several heat-related terms. This “priming”—additional “accessible” information—increased levels of belief in climate change.

As a further test, they asked 251 people about yesterday’s temperature (a memory), and found it did not influence their beliefs about climate change in the same way that today’s temperature (immediate experience) did.

In a final survey of 270 people, they asked about people’s memory of warmer-than-usual events. They found that an unusually warm day can prompt memories of other warm days, and lead people to overestimate the frequency of unusually warm days.

The paper follows a week of brutally cold temperatures across the U.S. Midwest and East. Of course it’s January, and this wasn’t by any means the region’s first winter deep freeze. But it was the coldest it’s been in many places in two decades.

The study’s lead author, Lisa Zaval, a graduate student in psychology at Columbia University working with the Center for Research on Environmental Decisions, said the survey’s findings about warm weather events could apply to cold ones, too.

“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,” she said. The study suggests the back-and-forth nature of how people form opinions on climate change could be confusing people, and have an important impact on how we form climate policies. “Strengthening the association between … cold weather, or extreme weather fluctuations, and climate change in people’s minds might be a good step.”

On the positive side, the chill prompted a lot of good science reporting explaining exactly what’s going on here—why the jet stream might become so loopy, and the larger context of temperatures around the globe and over time.

“This is the coldest weather in about 20 years,” writes Adam Sobel, an atmospheric scientist at the Lamont-Doherty Earth Observatory, in a piece for CNN’s website. “But it has happened before, and cold weather is happening less often overall. As stated in the latest report of the Intergovernmental Panel on Climate Change, it is ‘virtually certain’ that daily minimum temperatures (as well as daily maximum temperatures) over land have increased since 1950.”

He notes that last November was the warmest in recorded history, and high-temperature records have been repeatedly broken much more often than low-temperature records in recent years.

“But low-temperature records will still fall sometimes—when the [jet stream’s] wiggles happen to bring cold polar air to somewhere farther south than usual, or bring it faster than usual, before the sun can warm it. Some scientists argue, in fact, that global warming may actually cause this to occur more often.”

In a story published Jan. 8 by National Geographic online, climate scientist Gavin Schmidt of NASA’s Goddard Institute for Space Studies said, “People should stick to the basics of what we know, the long-term trends, and realize that what we are talking about are global averages. …

“The real story is that people have forgotten what cold weather is like. It was common 20 years ago.”

For more on the recent cold snap check out the perspective in these recent articles:

  • The Christian Science Monitor on Jan. 6 wrote about how climate change could have influenced the “polar vortex,” citing research by Lorenzo Polvani of Lamont-Doherty and others.
  • Andrew Freedman at Climate Central offered a longer-term perspective on the trends, including charts showing the long-term decline in cold days in various cities across the United States (two samples above and below).
  • The Associated Press analyzed daily temperature for the Lower 48 U.S. states going back to 1900 and found the U.S. experienced cold extremes about every four years—until recently. The deep freeze last week was the coldest it’s been in 17 years.

“These types of events have actually become more infrequent than they were in the past,” Greg Carbin, a meteorologist for the National Oceanic and Atmospheric Administration, told the AP. “This is why there was such a big buzz because people have such short memories.”


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