Studies have revealed that heuristics and accessible schemas may affect people's judgments about global warming. In two studies, participants were asked to report on beliefs regarding global warming while seated in a room in which a small tree or several trees had been placed. In one experimental condition, the tree possessed its foliage whereas in the other, the branches were bare. It was found that participants were more likely to believe in global warming in presence of the tree without foliage (Study 1), that this belief increased in presence of three rather than one tree without foliage (Study 2), and that other beliefs not related to global warming were not affected by the experimental conditions. These results reveal that surrounding physical cues do affect beliefs about global warming. The spreading activation theory is used to explain these results. (C) 2012 Elsevier Ltd. All rights reserved.