Through conversations with secondary school teachers, several tensions were identified in the enactment of climate change education vis-à-vis the sustainability paradigm, in an exploratory study of teachers’ knowledge, perceptions, and practices in Singapore. Teachers’ content knowledge of the subject is deficient. Their pedagogy is influenced by the perception that students are overexposed to the discourse, as well as the belief that there is enough coverage afforded to the topic across academic disciplines. Decisions on whether to prioritize topics depend on the weighting a topic commands in national high-stakes examinations. Cross-disciplinary collaborations and professional development activities to enhance content knowledge, and the use of appropriate pedagogy are recommended.