In this article, we study two Facebook groups in Sweden that address environmental issues, which adopt opposingly radical positions as it regards sustainability: one Facebook group supports climate change denialism, aligning with anthropocentrism, and one promotes the rights of nature movement and its ideas, embedded in ecocentrism. Employing discourse analysis, we exemplify how the radical positions that the two Facebook groups adopt demarcate the margins and the breadth of the spectrum of discourses around sustainability, but also how these positions signify the ideological struggle between anthropocentrism and ecocentrism, which lies behind the narratives of climate change denial or rights of nature, and structures their claims and radicality.