Dataset.

As public support influences policy choices, it is crucial to understand how people view climate policies. Based on the premise that individuals tend to be conditional cooperators, we derived the “They Reduce, We Reduce” hypothesis, according to which citizens’ support for climate policies in their own country is higher if they perceive a stronger climate effort by other countries. We tested this hypothesis with a survey study (N = 4,000) in China, India, Japan, and the United States. Findings show that participants who perceived that other countries were likely and willing to take action to reduce climate change, or that the major emitters in the world were currently making substantial efforts, were more supportive of implementing climate policies in their own country. We also observed interindividual variations in this effect, though the patterns differed between countries: The policy attitudes of individuals who felt personally obligated to combat climate change and those who supported their country’s unconditional efforts were less tied to such perceptions. These findings suggest that people respond to other countries’ actions, and policy attitudes should be understood in the context of global climate governance, with reciprocity playing an important role in mobilizing public support.