The purpose of this study is to examine the predictive effects of epistemological beliefs about science and informal reading of scientific texts on students' future-oriented optimism on the issue of climate change. Future-oriented climate change optimism is defined as encompassing "hope" and "anticipation" about the climate future. To identify the relationships among variables, structural equation modelling was conducted on the PISA dataset on 15-year-old students from Denmark, the UK and Finland which have the top three Environmental Protection Index. Students of all three countries demonstrated a consistently low optimism about the future of climate change. Also, the findings indicated that students' epistemological beliefs about science had a significantly negative predicting effect on their future-oriented climate change optimism across all three countries, while their informal reading of scientific texts had a significantly positive predictive effect on their future-oriented climate change optimism in Denmark and the UK. Across all three countries, 15-year-old students' awareness of the issue of climate change plays a significantly negative mediating role between their epistemological beliefs about science and their optimism in the future climate, as well as their informal reading of scientific texts and their optimism in the future climate. This calls for a new curricular environmental-science education model that addresses how students' informal science reading and epistemological beliefs about science can address future-oriented climate change optimism which might in turn impact young people's action competence to address the issues of climate change.