The Ethics of Geoengineering: Moral Considerability and the Convergence Hypothesis

Although it could avoid some harmful effects of climate change, sulphate aerosol geoengineering (SAG), or injecting sulphate aerosols into the stratosphere in order to reflect incoming solar radiation, threatens substantial harm to humans and non‐humans. I argue that SAG is prima facie ethically problematic from anthropocentric, animal liberationist, and biocentric perspectives. This might be taken to suggest that ethical evaluations of SAG can rely on Bryan Norton's convergence hypothesis, which predicts that anthropocentrists and non‐anthropocentrists will agree to implement the same or similar environmental policies. However, there are potential scenarios in which anthropocentrists and non‐anthropocentrists would seem to diverge on whether a particular SAG policy ought to be implemented. This suggests that the convergence hypothesis should not be relied on in ethical evaluation of SAG. Instead, ethicists should consider the merits and deficiencies of both non‐anthropocentric perspectives and the ethical evaluations of SAG such perspectives afford.