This study takes a critical mathematics education perspective when researching how focusing on climate change can facilitate students’ critical mathematical competencies. Climate Change is a global and urgent challenge, and mathematics plays a key role in describing, predicting, and communicating about climate change (Barwell, 2013, 2018). The conceptual framework is developed with the insights from the theoretical fields of critical mathematics education, general education and mathematics educational theory, interdisciplinary theory (in particularly STEM education), and post-normal science. An empirical study was carried out in lower secondary school; a research partnership with three mathematics and natural science teachers and their four 10^{th} grade classes. The data was collected over one year, and involved 42 lessons, constituting of seven themes; Startup, Excursion & Report, Dialogue Game, Discussions, Posters, Energy-exhibition, Dialogue & Debate.

Preliminary findings suggest that it is important to acknowledge the characteristics of tasks, reflect on students’ role in society, to identify important and relevant competencies, and recognise relevant aspects of democracy and mathematics education. When engaging in climate change in the mathematics classroom, this also includes a philosophical dimension, such as values and ethical concerns. Wicked problems such as climate change are perceived as a challenge by teachers, and their values influence facilitation. Furthermore, it is identified as important to develop an awareness of how mathematics is used in argumentation and allow enough time and opportunities for reflections on complex problems and collaborative research. Lastly, students’ critical mathematics competencies appeared when they engaged in inquiry-based dialogues, while they critiqued presuppositions, through (intertwined) mathematical, technological and reflective argumentation.