As the gravity of anthropogenic climate change is dawning on humanity, essential political aspects of the climatic situation remain unexplored. This article argues that our entering the Anthropocene amounts to a constitutive moment: a moment in which new principles of coexistence are being declared. Drawing on, as well as critically engaging with, the work of Bruno Latour and Hannah Arendt, I introduce and explicate the metaphor declarations of dependence to make sense of what scientists, activists, academics and journalists are doing, in political terms, when they announce the Anthropocene. Theoretically as well as practically, this metaphor opens for a more helpful understanding of the fraught relationship between science and the public on the issue of anthropogenic climate change. I end by considering the possibility that this metaphor, literally construed, can help us make today the first day in the rest of our lives in the Anthropocene.