Researchers have come up with a wide variety of strategies to get people to adopt more climate-friendly behaviors. But studies evaluating their effectiveness have generally been piecemeal, looking at the effect of individual strategies on individual climate-friendly behaviors. And differences in experimental design make it difficult to compare results across studies.
Enter the megastudy, a large-scale behavioral experiment akin to a randomized controlled trial in medicine. In new research published in the journal Science Advances, scientists tested the effectiveness of 11 different climate interventions on four different facets of climate psychology: climate beliefs, support for climate policy, willingness to share climate information with others (in this case, on social media), and propensity to take climate action (as gauged by an online task in which participants could proofread sets of numbers in exchange for donations to a tree-planting organization).
In addition, while past studies have usually focused on populations in wealthier, more industrialized countries, the new research involved participants from 63 countries around the world. Nearly 250 researchers collaborated on the study, which included 59,000 participants.
The findings suggest a widespread global consensus in favor of climate action: Overall, 86% of the study participants recognized the threat of climate change and 70% supported climate policy to address it.
But which strategies increase climate beliefs, policy support, and so on is more nuanced. Messages emphasizing the dire impacts of climate change emerged as the best way to get people to share climate information on social media, increasing willingness to share by 12%. On the other hand, this doom-and-gloom messaging decreased climate policy support among climate skeptics, and decreased support for tree planting in the overall study sample.
While none of the strategies increased tree-planting behavior, an intervention emphasizing that climate change affects people in the here and now, not just far-off people in the future, spurred the largest increase in climate belief (by 2.3%), while asking people to write a letter to a member of a future generation was the best way to strengthen policy support (by 2.6%).
In contrast to expectations from past studies, the researchers found that interventions emphasizing social norms or correcting misperceptions about other people’s climate beliefs weren’t very effective. “What mattered more than what other people are saying or doing, in this case, was thinking about one’s children and their futures,” says study team member Madalina Vlasceanu, assistant professor of psychology at New York University.
Overall, the effect of the various climate interventions was relatively small, the researchers found. “Our hunch is [this is] because of the heterogeneity in the samples being tested,” says study team member Kim Doell, a neuroscientist at the University of Vienna in Austria. In the study, the effect of interventions varied depending on participants’ initial level of belief in climate change, suggesting that messages need to be tailored based on this variable or perhaps others such as nationality, politics, age, gender, education, and income level.
This idea inspired the researchers to create a Climate Intervention Webapp to help policymakers and advocates zero in on the messages that are most effective in reaching different target groups. For example, emphasizing the scientific consensus on climate change increased climate policy support by 9% in Romania, but decreased it by 5% in Canada.
In the United States, writing a letter to a member of a younger generation is a powerful way to increase climate belief, climate policy support, and willingness to share climate information among those on the political right. “Those who are politically right-winged tend to be the least likely to support such policies, so this would suggest that this is a really good intervention to leverage in the US,” says Doell. “As a bonus, this same intervention tends to be the best one for the politically left as well!”
Meanwhile, says Vlasceanu, “if you’re talking to someone who is still uncertain [about climate change], the most useful topics to bring up in conversation are: the consequences in their immediate geographic region (e.g., wildfires, floods, drought, heatwaves, food shortages, etc.); the impact on their children in just a couple of decades; [and] the usefulness and efficacy of engaging in collective action.”
The researchers are now conducting a similar effort to identify the best ways to stimulate climate advocacy rather than just individual climate action, and they’re crowdsourcing strategies to test.
Source: Vlasceanu M. et al. “Addressing climate change with behavioral science: A global intervention tournament in 63 countries.” Science Advances 2024.
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