This paper presents the argument that climate change should be taught in schools as a sociopolitical and scientific process, and that students should be able to use their science knowledge to think critically about climate change as a social justice issue. A necessary and achievable outcome of science education is critical climate awareness--an understanding of the systems and structures that create and sustain climate change inequities. Through a participatory design research partnership, a high school chemistry course was designed and studied that focused on this outcome. Data from a single group, mixed method pre/postdesign show how a group of Black and Latinx urban youth appropriated critical climate awareness from the curriculum they experienced and how they used this awareness to explain climate change as a scientific and sociopolitical process. The findings show that students became concerned about climate change, if they were not already, and that they improved their knowledge of scientific concepts specific to climate change. In their explanations of climate change, students foregrounded sociopolitical processes that result in changes to physical systems, assigned agency for carbon emissions to diverse social actors in ways attentive to power dynamics, and articulated differences in consequences and solutions based on the racial and socioeconomic demographics of communities. This work has implications for transforming science classrooms into incubators for climate justice.