A 27-country study tested the effectiveness of two scientific consensus messages on climate change: a classic message emphasizing the reality of human-caused climate change and an updated message adding that climate change is a crisis. Across 10,527 participants from 27 countries, the classic message significantly reduced misperceptions of the scientific consensus (d = 0.47) and slightly increased beliefs (d = 0.10) and worry (d = 0.05) about climate change, but had no direct effect on support for public action. The updated message was equally effective but did not add value. Both messages were more effective for audiences with lower familiarity with the message, higher misperceptions, and lower trust in climate scientists, including those with right-leaning ideologies. The study found that scientific consensus messaging is an effective, non-polarizing tool for reducing misperceptions and shifting beliefs and worry about climate change across diverse audiences. However, it had limited direct impact on support for public action. The updated message, which emphasized the crisis aspect of climate change, showed only weak additional effects on belief in climate change as a crisis and support for public action. The results suggest that scientific consensus messaging is most effective for individuals with lower initial consensus perceptions and lower trust in climate scientists. The study highlights the importance of communicating the scientific consensus on climate change to reduce misperceptions and promote climate action. However, the effectiveness of such messaging may vary depending on individual and country-level characteristics. The findings underscore the need for targeted communication strategies that address specific audience needs and contextual factors. The study also emphasizes the importance of considering cultural and political dimensions when designing climate communication strategies. Overall, scientific consensus messaging remains a valuable tool for promoting climate awareness and action, particularly in contexts where public understanding of the scientific consensus is limited.A 27-country study tested the effectiveness of two scientific consensus messages on climate change: a classic message emphasizing the reality of human-caused climate change and an updated message adding that climate change is a crisis. Across 10,527 participants from 27 countries, the classic message significantly reduced misperceptions of the scientific consensus (d = 0.47) and slightly increased beliefs (d = 0.10) and worry (d = 0.05) about climate change, but had no direct effect on support for public action. The updated message was equally effective but did not add value. Both messages were more effective for audiences with lower familiarity with the message, higher misperceptions, and lower trust in climate scientists, including those with right-leaning ideologies. The study found that scientific consensus messaging is an effective, non-polarizing tool for reducing misperceptions and shifting beliefs and worry about climate change across diverse audiences. However, it had limited direct impact on support for public action. The updated message, which emphasized the crisis aspect of climate change, showed only weak additional effects on belief in climate change as a crisis and support for public action. The results suggest that scientific consensus messaging is most effective for individuals with lower initial consensus perceptions and lower trust in climate scientists. The study highlights the importance of communicating the scientific consensus on climate change to reduce misperceptions and promote climate action. However, the effectiveness of such messaging may vary depending on individual and country-level characteristics. The findings underscore the need for targeted communication strategies that address specific audience needs and contextual factors. The study also emphasizes the importance of considering cultural and political dimensions when designing climate communication strategies. Overall, scientific consensus messaging remains a valuable tool for promoting climate awareness and action, particularly in contexts where public understanding of the scientific consensus is limited.