As efforts to reduce greenhouse gas emissions stall, some scientists advocate for technological interventions into the climate system (“geoengineering”). In this lecture, sponsored by the Logic and Politics of Climate Change project, Stephen Gardiner (Professor of Philosophy, University of Washington) discussed the ethical issues raised by the prospect of geoengineering—including concerns about welfare, rights, justice, and political legitimacy. What should we do, ethically speaking, given that we will not do what we should be doing? This paradoxical question helped to explain why geoengineering may be ethically troubling and highlights the largely neglected threat that geoengineered interventions discriminate against future generations. Far from being a welcome new tool for climate action, geoengineering may become yet another manifestation of the underlying problem.