This article explores the existential conditions for a transition towards socioeconomic degrowth through an analysis of a paradigm shift between two extreme polarities of socio-ecological positioning: the Dominant Social Paradigm (DSP) and the New Ecological Paradigm (NEP). It is suggested that the transition from one to the other – understood as the first collective step towards degrowth – requires a transformation in the way we, in western capitalist society, define ourselves in relation to nature. This identity transformation corresponds with the reconnection between humans and nature that ecopsychology has been calling for since its emergence in the 1970s. However, according to recent empirical studies in existential psychology, such a transformation contains potentially disquieting aspects, since it implies recognising and accepting the idea of our own mortality. Staging a dialogue between ecopsychology and critical degrowth theories, this article argues that the necessary transition towards degrowth requires new ways of dealing with these existential fears – namely, confronting them in a ‘reflexive’ rather than ‘defensive’ way – so as to develop relationships with nature that respect the limits of the biosphere.