This article examines how Holocaust memory shapes contemporary representations of climate change. Despite the climate crisis being unprecedented in human history, its cultural imagination often draws on historical calamities such as the Holocaust, nuclear annihilation, and colonial destruction. Employing the concepts of postmemory, multidirectional memory, and anticipatory memory, together with the notion of an ethics of comparison, the article explores how narratives of genocide serve as mnemonic templates for understanding environmental collapse while also assessing the ethical stakes of such analogies. It analyses public debates, academic discourse, and climate fiction, revealing how Holocaust comparisons function as rhetorical devices that mediate future-oriented anxieties and heighten the urgency of climate action. While these analogies are contentious and ethically fraught, risking trivialisation or historical distortion, they also mobilise the affective and political force of memory to confront the enormity of the climate crisis. Finally, the article turns to the genocide–ecocide nexus, arguing for an expanded framework of multidirectional eco-memory that acknowledges the entangled vulnerabilities of human and non-human life.