This article introduces a typology of nine communication frames and analyzes how they operate in Bill Gates's How to Avoid a Climate Catastrophe (2021) and Greta Thunberg's The Climate Book (2022). The typology draws special attention to how non-fiction books are vehicles that can appeal for timely action (i.e. kairos), establish authorial ethos, disseminate climate science, and advocate for climate activism and energy transitions. The application of the typology highlights the books' narrative arcs: Gates and Thunberg both begin by acknowledging the reality and severity of the climate crisis and the correspondence between social progress and justice. Then, their arguments diverge: Thunberg critiques ineffective policies, cites climate science, and urges immediate social action; Gates provides economic context to support his appeals for innovation spurred by applied science. Towards their conclusions, the two authors' rhetorical appeals converge again as they each advocate for timely action. The results of this thematic analyses reinforce the value of book-length arguments that engage scientific evidence and envisage urgent individual and collective responses to climate crises.