Acceptance of global warming rises on warm days

Last week, much of the United States experienced the coldest weather in two decades, as temperatures plummeted below freezing in many states. Many newscasters on conservative media outlets were using the record-breaking cold snap to deny the existence of global warming, making comments such as “All of this snow and still cries of global warming.” Similar claims appeared on social media.

We are experiencing the coldest weather in more than two decades-most people never remember anything like this. GLOBAL WARMING anyone?

— Donald J. Trump (@realDonaldTrump) January 6, 2014

This sort of media coverage happened before, during the so-called snowpocalypse of 2010 in Washington DC. But perhaps we shouldn’t judge them too harshly. Local weather and short-term temperature variations—even if today feels warmer or colder than usual—can influence an individual’s acceptance of climate change. This effect is known as local warming.

In a new study, people who perceived the day’s temperature as warmer than usual believed more strongly in global warming and were more concerned about it. Rather than relying on relevant information to form an opinion on climate change—such as global temperature trends—they instead substitute information that didn't take as much effort to obtain, such as today’s temperature. Because individuals are sensitive to information that should be irrelevant to their judgments regarding climate change, the researchers think that people reconsider their opinion each time they are asked about their belief in climate change.

To test whether phrasing, knowledge level, or availability of information was responsible for influencing a person’s judgment, the team of researchers set up a series of experiments. At first, they thought perhaps the phrase “global warming” would conjure thoughts of heat-related impacts and rising temperatures, and it might be responsible for the local warming effect. Participants were asked to complete a survey about their belief in and concern about the phenomenon, which was described as either “global warming” or “climate change.” Then, they were asked to report whether the local temperature that day was warmer or colder than usual for that time of year.

It turns out that the local warming effect persisted regardless of whether you call it climate change or global warming.

The con artists changed the name from GLOBAL WARMING to CLIMATE CHANGE when GLOBAL WARMING was no longer working and credibility was lost!

— Donald J. Trump (@realDonaldTrump) December 31, 2013

Thinking that a limited understanding of climate science may be to blame for people incorrectly using short-term temperature to assess their belief in global warming, they set up a second experiment. Participants were split into two groups: one that read a passage explaining the differences between minor weather fluctuations and global climate change and one that read a passage on the science of sleep. All participants were then asked the same temperature, belief, and concern questions from the first study.

Being armed with a greater knowledge of climate science did not erase the local warming effect—participants who read the climate science passage were still more likely to believe in and be concerned about global warming if they perceived today to be warmer than usual.

The researchers then moved on to their last hypothesis: when the mind is primed to the concept of heat or cold, the concept is more likely to be used in evaluating climate change. The researchers gave participants either heat or cold-priming tasks before asking them about the same belief and concern questions as the previous experiments. When primed with a heat-related thought, individuals’ belief and concern in global warming increased.

Understanding the psychology that influences climate change belief and concerns can help shape how communicators convey this complex issue, enabling them to provide a more accurate perspective on the subject. This could have important implications for public policy. In a 2013 Pew Research Center annual policy priorities survey, dealing with global warming ranked at the bottom of the list of 21 priorities, with only 28 percent saying that it should be a top priority for the president and Congress.

Nature Climate Change, 2014. DOI: 10.1038/NCLIMATE2093  (About DOIs).