How Stable is Earth’s Climate?
Americans have very different mental models of the stability of the climate system. In a nationally representative study, we examined Americans’ understanding of how the climate system works. Survey respondents were presented with the following question:
“People disagree about how the climate system works. The five pictures below illustrate five different perspectives. Each picture depicts the Earth’s climate system as a ball balanced on a line, yet each one has a different ability to withstand human-caused global warming. Which one of the five pictures best represents your understanding of how the climate system works?”
Fragile: Earth's climate is delicately balanced. Small amounts of global warming will have abrupt and catastrophic effects.
Threshold: Earth's climate is stable within certain limits. If global warming is small, climate will return to a stable balance; if it is large, there will be dangerous effects.
Gradual: Earth's climate is gradual to change. Global warming will gradually lead to dangerous effects.
Random: Earth's climate is random and unpredictable. We do not know what will happen.
Stable: Earth's climate system is very stable. Global warming will have little or no effects.
Figure 1: Americans' mental models of the climate system (Data Source: Leiserowitz et al., 2010).
Most respondents chose the Threshold model (34%), followed by the Gradual (24%), Random (21%), Fragile (11%) and Stable (10%) models. Scientifically, at different temporal or spatial scales the climate system can exhibit each of these behaviors, but the best overall answer is the threshold model.
We also asked: "Do you think global warming is happening?" Overall, 63% of Americans said "Yes", 19% said "No," and 18% said "Don't know." We then compared how Americans' mental models of the climate system relate to their understanding that global warming is happening. Figure 2 depicts the proportion of respondents who said that global warming is happening, within each mental model. For example, of those Americans who chose the Fragile model, 79% said that global warming is happening. By contrast, of those Americans who chose the Stable model, only 21% said global warming is happening, while 64% said it is not happening.
Figure 2: Understanding that global warming is happening by mental models of the climate system (Data Source: Leiserowitz et al., 2010).
Summary: Americans who have a Threshold, Gradual, or Fragile mental model of the climate system are more likely to understand and accept that global warming is happening. Americans who have a Random or Stable mental model of the climate system, however, are less likely to understand or accept that global warming is happening. Whether one's mental model influences belief in global warming, or vice versa, however, cannot be determined by this analysis.