Solar radiation management (SRM), a form of climate engineering, would offset the effects of increased greenhouse gas concentrations by reducing the amount of sunlight absorbed by the Earth. To encourage support for SRM research, advocates argue that SRM may someday be needed to reduce the risks from climate change. This paper examines the implications of two moral constraints—the Doctrine of Doing and Allowing, and the Doctrine of Double Effect—on this argument for SRM and SRM research. The Doctrine of Doing and (...) Allowing, and perhaps the Doctrine of Double Effect, shows that the argument is weaker than it appears. (shrink)