Using new surveys on more than 40,000 respondents in twenty countries that account for 72% of global CO2 emissions, we study the understanding of and attitudes toward climate change and climate policies. We show that, across countries, support for climate policies hinges on three key perceptions centered around the effectiveness of the policies in reducing emissions (effectiveness concerns), their distributional impacts on lower-income households (inequality concerns), and their impact on the respondents’ household (self-interest). We show experimentally that information specifically addressing these key concerns can substantially increase the support for climate policies in many countries. Explaining how policies work and who can benefit from them is critical to foster policy support, whereas simply informing people about the impacts of climate change is not effective. Furthermore, we identify several socioeconomic and lifestyle factors – most notably education, political leanings, and availability of public transportation – that are significantly correlated with both policy views and overall reasoning and beliefs about climate policies.