In this paper I argue that individuals are, prior to the existence of just institutions requiring that they do so, bound as a matter of global distributive justice to restrict their use, or share the benefits fairly of any use beyond their entitlements, of the Earth's capacity to absorb greenhouse gases (EAC) to within a specified justifiable range. As part of the search for an adequate account of climate morality, I approach the task by revisiting, and drawing inspiration from, two prominent models from classical political philosophy for thinking about norms (rights, permissions, limits, etc.) regarding “pre-institutional” appropriation of unowned resources; Locke and Kant, respectively. The basic resources they develop—connected to fundamental norms of equality and rights to self-preservation and freedom—in order to generate their particular schema for distributive shares prior to the existence of just institutions can be usefully and plausibly connected with the scarce, valuable, rival, non-excludable, global, and unowned resource that is EAC in order to undergird a picture of individual climate duties in the contemporary world. It is a picture that comes with some fairly radical implications, especially for the well-off.