ABSTRACT
Each of the next four chapters addresses a specific dimension of the ethics of climate engineering. Chapter one focuses on the potential outcomes of SRM, including both beneficial and harmful impacts. Proponents of researching climate engineering contend that, despite some harmful impacts (e.g., due to precipitation change), SRM could reduce many of the harms of anthropogenic climate change by slowing or even halting planetary warming. Thus, in certain future scenarios, SRM might yield less harm and more benefits (on the whole) than other policies, such as those involving adaptation or mitigation alone. While there is some plausibility to the claim that SRM could provide a comparatively attractive balance of harms and benefits in some cases, this broadly consequentialist line of reasoning faces two important problems. First, the impacts of SRM (and climate change more generally) are uncertain. Climate model simulations provide only probabilities of certain (more or less severe) physical impacts of SRM, such as regional changes in precipitation patterns. So in comparing available climate policies, we cannot simply assume that each policy will have a given set of impacts. Instead, a consequentialist assessment of climate policies needs to take into account the probabilities of various impacts. There are methods for doing this, of course, such as that of expected utility maximization. Unfortunately, there is deep uncertainty (also known as ambiguity of Knightian uncertainty) regarding many of the impacts of SRM techniques, meaning that different climate model simulations provide divergent probability density functions. This suggests that, in many cases, we will not know the relevant probabilities to use in expected utility calculations, which is a problem for consequentialist arguments in favor of SRM. The second problem for such arguments is that they overlook the question of distributive justice. Even assuming that some policy involving SRM would deliver the best overall balance of benefits to harms, those harms and benefits might be distributed in unjust ways.
