The ethics of negative emissions

Non-technical abstract Limiting dangerous climate change is widely believed to require negative emissions. This prospect has sparked concerns about whether negative emissions could be scaled up quickly enough, along with concerns about their likely ethical costs. Building upon scenario modelling, this paper examines ethical concerns with negative emissions via the comparison of three alternate climate futures. This paper shows that the severity of concerns depends upon implementation conditions, and especially the extent of deferred mitigation. Negative emissions can be a valuable means of limiting dangerous climate change, or an unjust gamble against the future. Technical abstract Limiting dangerous climate change is widely believed to require negative emissions. This prospect has sparked concerns about whether negative emissions could be scaled up quickly enough, along with concerns about their potential ethical costs. To date, however, ethical analysis of negative emissions has been very limited. In this paper, three main concerns are identified, namely that negative emissions may obstruct mitigation both in climate modelling and in policy; that they may encourage a dangerous policy gamble; and that they may overestimate our ability to manage the carbon cycle and thus to deliver significant carbon removal. This paper then attempts an assessment of their potential severity via the comparison of three alternate climate futures. This paper shows that the severity of concerns depends greatly upon implementation conditions, and especially the extent of deferred mitigation. Consequently, negative emissions can be either a valuable means of limiting dangerous climate change, or an unjust gamble against the future.