Climate change communication on social media plays a prominent role in efforts undertaken by state agencies, NGOs, and international organizations, to make citizens aware of this phenomenon. The images used to communicate climate change are of great importance, since they can help to effectively raise citizen awareness. Building upon news values theory and the concept of availability heuristics, this research paper aims to identify principles that can be used for effective visual communication of climate change on social media on a cross-national scale, based upon analyses of characteristics of images that foster interaction on Twitter. We conducted a content analysis of a random selection of images (photographs, illustrations, and graphics, n = 380), posted on Twitter that were included in the so-called 'top tweets' about climate change. The results indicate that the types of images that are used on social media are relatively similar to those employed by conventional media, although images of identifiable people are less frequently shown on social media. We also deduced that four practical principles are especially relevant to foster user interaction on Twitter through images: (i) show 'real people' (i.e. non-staged images of people that transmit real emotions), (ii) tell a story, (iii) include a local connection, and (iv) show impacts or actions by people who are directly affected. These practical principles are based on the more general principles of meaningfulness and personification, two foundations that can help to overcome some of the main barriers to citizens' perception of climate change as a relevant issue with serious consequences in their lives. Campaigns on social media that use imagery based on these practical and general principles can be effective in communicating the shared responsibility to address climate change. This can have a relevant impact on social perception, since it can encourage citizens to care about climate, which is regarded as necessary to increase participation in climate action. Key policy insights Social media can play a prominent role in campaigns to make citizens aware of climate change. Images can help to effectively raise citizen awareness of climate change. Four practical principles can be effective in increasing user interaction on social media with images about climate: show 'real' people, tell a story, include a local connection, and show people who are directly affected. Visual campaigns based on the more general principles of meaningfulness and personification can be effective in representing climate change as a relevant issue in citizens' lives. These practical and more general principles can have a relevant impact on the social perception of climate change and increase citizen participation in climate debate and action.