Earth systems science maintains that there are nine “planetary boundaries” that demarcate a sustainable, safe operating space for humankind for essential global sinks and resources. Respecting these planetary boundaries represents the “strong sustainability” perspective in economics, which argues that some natural capital may not be substituted and are inviolate. In addition, the safe operating space defined by these boundaries can be considered a depletable stock. We show that standard tools of natural resource economics for an exhaustible resource can thus be applied, which has implications for optimal use, price paths, technological innovation, and stock externalities. These consequences in turn affect the choice of policies that may be adopted to manage and allocate the safe operating space available for humankind.