Climate change is increasingly affecting our planet, impacting people’s health, security and livelihood, as well as wider biodiversity. Given this, it is perhaps not surprising that many studies have identified ‘climate anxiety’ (or ‘eco-anxiety’) as an emotional response to these events. Numerous studies have found that anxiety regarding climate change is associated with worse mental health, such as higher rates of depressive and anxiety symptoms, although the majority of these studies are small, cross-sectional and from unrepresentative samples, limiting both generalisability and the extent to which causal conclusions can be drawn. There is therefore a need to explore these questions using data from a large-scale longitudinal population-based study; this is what we intend to do here, using data from ALSPAC.