LETTERS PUBLISHED ONLINE: 2 DECEMBER 2012 | DOI: 10.1038/NCLIMATE1754 The relationship between personal experience and belief in the reality of global warming Teresa A. Myers 1 * , Edward W. Maibach 1 , Connie Roser-Renouf 1 , Karen Akerlof 1 and Anthony A. Leiserowitz 2 In this paper, we address the chicken-or-egg question posed by two alternative explanations for the relationship between perceived personal experience of global warming and belief certainty that global warming is happening: Do observable climate impacts create opportunities for people to become more certain of the reality of global warming, or does prior belief certainty shape people’s perceptions of impacts through a process of motivated reasoning 1 ? We use data from a nationally representative sample of Americans surveyed first in 2008 and again in 2011; these longitudinal data allow us to evaluate the causal relationships between belief certainty and perceived experience, assessing the impact of each on the other over time 2 . Among the full survey sample, we found that both processes occurred: ‘experiential learning’, where perceived personal experience of global warming led to increased belief certainty, and ‘motivated reasoning’, where high belief certainty influenced perceptions of personal experience. We then tested and confirmed the hypothesis that motivated reasoning occurs primarily among people who are already highly engaged in the issue whereas experiential learning occurs primarily among people who are less engaged in the issue, which is particularly important given that approximately 75% of American adults currently have low levels of engagement 3,4 . Climate change is affecting every region by increasing the frequency and/or intensity of heat waves, droughts, precipitation, floods, hurricanes, and forest fires, and through impacts on ecosystems and species, including human health 5 . Yet, most Americans perceive climate change as a problem distant in time and space, and do not recognize its indicators and impacts in their own localities 4,6 . Moreover, despite widespread agreement among climate scientists that human-caused climate change is occurring 7 only two-thirds (66%) of Americans adults correctly understand that ‘global warming is happening’, and nearly half of these are only ‘somewhat sure’ (42%) or ‘not at all sure’ (5%) of their answer; moreover, only a third believe that they or their families will be harmed 4 . Low levels of belief certainty and perceived threat, in turn, indicate low levels of engagement with the issue, which is strongly associated with reduced levels of support for taking action to address the problem 8 . One possible explanation for these low levels of belief certainty— and perceptions of the threat as distant—is that climate change is difficult to perceive directly; ‘climate’ itself is a statistical abstraction, even though its impacts can be quite tangible 9 . Current theories of cognitive science suggest that learning about abstractions requires analytical information processing, which 1 Center for Climate Change Communication, George Mason University, Fairfax, Virginia 22030, USA, 2 School of Forestry, Yale University, New Haven, Connecticut 06511, USA. *e-mail: tmyers.6@gmu.edu. involves cognitive effort—a scarce commodity, which people expend sparingly 10 . Both low motivation to think about climate change and low ability to comprehend scientific information 11 can impede people’s processing of the charts, graphs and models in the climate scientist’s toolkit. By contrast, experiential processing—learning through experience—is much more likely to occur: it happens automatically, effortlessly and instantly, and has strength and immediacy that analytical information lacks. Peoples’ impressions of climate change are probably shaped in large measure by their strong propensity for experiential processing, yet information about climate change is often presented in abstract analytical terms that are hard for people to process and connect to their own lives 12 . Common in both scientific and media reports 13 , abstractions make for pallid education, and are less convincing than the vividness of personal experience. Indeed, people who say they have personally experienced global warming are far more likely to be engaged with the issue than people who say they have not 1,14,15 . More than a quarter of the American public believe they have personally experienced the effects of global warming 4 , and that belief is strongly associated with higher global warming risk perceptions 16 , worry 17 , and response motivation 18 . This pattern of relationships suggests the possibility that as individuals experience the effects of global warming, they become more certain that global warming is occurring. However, a rival hypothesis suggests that perceptions of personal experience stem from prior beliefs through a process of motivated reasoning rather than from impartially detecting changes in their local environment. The literature on motivated reasoning in general—and cultural cognition in particular 19 —has demonstrated that people’s prior beliefs about climate change can strongly influence how they interpret changes in environmental conditions (see also literature on Bayesian updating for a competing perspective 20 ). People tend to seek (or avoid) and process information— often using mental shortcuts—in a manner that is favourable to their preferred conclusions 21 . Evidence that is consistent with the desired attitude is accepted at face value, while conflicting evidence is ignored, dismissed, or subjected to critical review 22 . Value- inconsistent information can lead to ‘boomerang’ effects (that is, strengthening prior beliefs) 23 , and can be avoided, forgotten, or distorted 24 , particularly in situations where an individual feels powerless to reduce a potential threat 22 . There is considerable evidence that motivated reasoning influ- ences some people’s global warming beliefs. Political ideology, egal- itarianism, and individualism, for example, are strongly associated NATURE CLIMATE CHANGE | ADVANCE ONLINE PUBLICATION | www.nature.com/natureclimatechange 1 © 2012 Macmillan Publishers Limited. All rights reserved.