On June 23, 1988, record 38°C temperatures in Washington DC provided a persuasive backdrop for NASA’s Jim Hansen to force the greenhouse effect into our consciousness. At least one of the senators hearing his landmark congressional testimony was well aware that the heat would help sear the message into people’s minds. Tim Wirth has since admitted turning off the air conditioning and opening the windows the night before, so Jim’s sweat would be obvious for the TV cameras.
That baking hearing likely played on how we think in a way psychologists had just started to untangle in the previous decade. That is, how we judge things is often dominated by a simple sense of our personal experience, rather than a deeper analysis of evidence available to us. “Numerical judgments are hard, so we grasp at whatever more tangible we can find,” Elke Weber, from Columbia University in New York, explained.
Identifying this tendency to answer an easier question, known as substitution, helped psychologist Daniel Kahneman win a Nobel Prize for Economics. And when it comes to our opinion on climate change, recent temperatures are especially important, Elke and her colleagues have shown over the last three years.
In 2010, a rather different extreme in the US capital drew Elke’s husband Eric Johnson to study this effect. Then, two massive snowstorms struck in one week in February, an event that was dubbed the ‘Snowpocalypse’, leading senators to deride the possibility of climate change. His team therefore looked at whether local weather information gets falsely substituted for global climate in three studies in the US and Australia.
Across three studies they asked people their opinions on global warming and whether the temperature on the day of the study was warmer or cooler than normal. Those who thought that day was warmer than usual believed more in and had greater concern about global warming than people who thought that day was colder than usual. They would also donate more money to a global-warming charity if they thought that day seemed warmer than usual.
Too hot to think?
That’s instinctively easy to believe, but what may be surprising is that the temperature substitution effect beats other psychological factors thought to influence opinions on climate change. Eric, Elke and their colleagues compared it against two other factors in another paper published in Nature Climate Change in January this year.
One factor is how the effect is labelled, simply whether a question asks about ‘climate change’ or ‘global warming’. Some scientists have found that global warming puts heat into people’s minds and therefore influence their answers. Elke, Eric and their team therefore asked another 686 people about their belief and concern over global warming and the current temperature. And although this time they asked half about climate change rather than global warming, they found both phrasings performed similarly.
The factor that might seem to be most important of all is how much people knew about climate science beforehand. So in a study with 330 people, Elke and Eric’s team asked half to read a passage highlighting the differences between minor weather fluctuations and global climate change. They asked the other half to read a passage on the science of sleep. After a comprehension test, they again asked the questions about belief in and concern about global warming and local temperature.
Again the results of temperature were far stronger than the effect of information. Along with other experiments into how the effect works, Elke feels these results have convinced other scientists of how important temperature substitution is. “The fact that our paper tested various other explanations and ruled them out, has made other explanations much less likely,” she told me.
That our opinions and beliefs literally change with the weather helps explain why trying to decide on and enact appropriate ways to handle global warming’s risks is so hard. “My husband often compares the use of today’s temperature deviation from normal as an indication of global climate change to a person looking at how much change he has in his pockets to answer a question about how well the US economy is doing,” Elke points out.
A risk we don’t dread
The difficulties may be worsened because we likewise judge many risks on our direct experience rather than ‘description’ – what we read or are told. “It helps explain why experts and the general public sometimes disagree about the riskiness of something, be it the risk posed by vaccinations or by coastal flooding,” Elke noted. “It also helps with designing more effective risk communication that can correct possible misperceptions by better interventions.”
However direct experience of warming’s impacts might allow us to override the more immediate of temperature, the Columbia researcher added. “If and when we do have extensive personal experience with climate change impacts, for example in the form of frequent and stronger extreme weather events like storms or coastal flooding, those experiences will determine our attitudes and actions on climate change far more than how hot or cold it is the day I am being asked about it.”
These irrational peculiarities of ours are now a subject of study called behavioral decision theory, which was pioneered by Daniel Kahneman, his collaborator Amos Tversky, and Paul Slovic. Elke has worked with Paul, and been influenced by his idea of ‘psychological risk dimensions’. “I coined the term ‘risk as feelings’ a while back,” she explained. “In 2006 I speculated that climate change is not high on our individual and societal agenda because it does not elicit visceral reactions. Just a couple of months ago, I eventually got a graduate student to test my prediction and am gratified to say that she proved me right: climate change does not score on ‘dread’.”
Alongside work on how to promote energy efficiency, Elke is now studying ways to overcome this need for a strong emotional driver to act. “I look at other contextual variables that may make it more likely for us to act on our longer-term goals and objectives which get too easily overridden with our chronic concern for the here and now,” she said. She consequently became the first psychologist to work on UN Intergovernmental Panel on Climate Change reports in its latest assessment. “I contributed a section on non-rational judgment and choice processes to the report, the first time that processes other than rational expectations and choice have been considered and mentioned by that body.”
With the Northern Hemisphere summer now making the kitchen I’m writing this in uncomfortably warm and sticky, I certainly want to avoid things getting much warmer. And with the heat both coincidentally and deliberately influencing people, I can also imagine why the 1988 hearing might have seemed so powerful – and so can Elke. “It was definitely an effective move in terms of getting attention to the issue, ‘illustrating’ the statistical points that Jim Hansen made with the much more salient personal experience of stifling heat,” she emphasised.
Weber, E. (2006). Experience-Based and Description-Based Perceptions of Long-Term Risk: Why Global Warming does not Scare us (Yet) Climatic Change, 77 (1-2), 103-120 DOI: 10.1007/s10584-006-9060-3
Li, Y., Johnson, E., & Zaval, L. (2011). Local Warming: Daily Temperature Change Influences Belief in Global Warming Psychological Science, 22 (4), 454-459 DOI: 10.1177/0956797611400913
Zaval, L., Keenan, E., Johnson, E., & Weber, E. (2014). How warm days increase belief in global warming Nature Climate Change, 4 (2), 143-147 DOI: 10.1038/nclimate2093