Via thematic content analysis, this article combines approaches from educational and literary research to explore representations of nature, climate change and sustainability "by" children in their own reflections and "for" children in fiction. The primary materials consist of ethnographic studies conducted in Swedish schools in 2011 and 2013, and of close readings of Julie Bertagna's trilogy "Exodus" (2002), "Zenith" (2003), and "Aurora" (2011). Representations by young learners, as well as themes in climate fiction, reflect concerns regarding climate change, a critical awareness of anthropogenic influences, and a conviction that cooperation is essential to promote change. Speculative climate fiction can assist when re-thinking current structures and patterns by letting readers encounter possible scenarios in a safe space, in this way broadening discussions regarding future sustainability. We identify a number of contact points between our materials and suggest how findings point to bright spots when re-thinking the role of literature in education for sustainable development (ESD) and, conversely, the importance of young learners' voices within ESD for literature studies.