One of the major questions around solar geoengineering is often summarized under the term “moral hazard”: could mere mention of the topic, or research into it, crowd out mitigation efforts? Some surveys support this “crowding out” hypothesis, while others point to the opposite effect: talk of solar geoengineering acting as a wake-up call that crowds in mitigation efforts. We here take this question online and conduct large-scale experiments on a social media platform to elicit under which conditions which effect dominates. We compare people’s reactions to different presentations of climate change and of solar geoengineering and observe their subsequent engagement with environmental topics. We hope this informs our understanding how a broad public might engage with solar geoengineering topics vis-à-vis an overall climate policy portfolio.