The Ethics of Distribution in a Warming Planet

The discounted-utilitarian social welfare function (DU) is used by the great majority of researchers studying intergenerational resource allocation in the presence of climate change (e.g., W. Nordhaus, M. Weitzman, N. Stern, and P. Dasgupta). I present three justifications for using DU: (1) the view that the first generation's preferences should be hegemonic, (2) the viewpoint of a utilitarian Ethical Observer who maximizes expected utility when the existence of future generations is uncertain, and (3) axiomatic justifications (as in classical social-choice theory). I argue that only justification (2) provides an ethically convincing justification, and that, only if one endorses utilitarianism as a good ethic. Recent work by Llavador, Roemer and Silvestre challenges the utilitarian assumption, and argues that sustaining human welfare at the highest possible level forever, or sustaining the growth rate of human welfare (at a fixed exogenous growth rate), are more attractive ethical choices. The work of these authors, which studies the optimal intergenerational paths of resource allocatiobn under the sustainabilitarian objectives, is briefly reviewed and contrasted with the discounted-utilitarian approach.