Teachers are at the front line of climate change education (CCE), working to integrate its complex environmental, social and ethical dimensions into their classroom practice. Yet little is known about the barriers to and enablers of implementing interdisciplinarity within CCE. This study investigates Finnish secondary school teachers’ perspectives on interdisciplinary CCE, examining how their practices are shaped by access to resources, training and institutional support. Drawing on the ecological model of teacher agency, we conduct a mixed-methods analysis from a national survey of 243 teachers. The findings reveal a strong commitment to locally relevant and ethically informed CCE, as well as an increased interest in activities in outdoor environments, research-based resources and drama-based resources. On the other hand, an increased disinclination to introducing new content and resources highlights the persistence of structural, epistemological, and ideological barriers. Teachers report relying heavily on self-directed learning and growing interdisciplinary fatigue due to fragmented support systems. These dynamics reveal a need for academic–school collaborations that move beyond top-down implementation and towards the creation of accessible, adaptable knowledge. This study contributes to emerging debates about how to foster critical interdisciplinarity in CCE by centring the voices and agency of educators.