It is often stated that optimal global climate policy requires global harmonization of marginal abatement costs – i.e., a single carbon price throughout the world. Chichilnisky and Heal (1994) have shown quite generally that this is only the case if distributional issues are ignored, or if lump-sum transfers are made between countries. Else, a policy in which different regions face different carbon prices may be superior to one with a single global carbon price from a welfare point of view. Still, (...) most integrated assessment models (IAMs) assume away distributional issues and report a single optimal carbon price. We calculate utilitarian-optimal carbon prices under zero cross-regional lump-sum transfers in the multi-region IAM NICE. The result is optimal global climate policy with different regional carbon prices in which the poorest regions face initially low prices, while the richest regions face very high prices from the outset. This entails significant welfare gains over the standard single price optima commonly reported, which, as we argue briefly in conclusion, can be improved upon still by allowing international trading in the corresponding emissions allocations. (shrink)

This book analyzes major ethical issues surrounding the use of climate engineering, particularly solar radiation management techniques, which have the potential to reduce some risks of anthropogenic climate change but also carry their own risks of harm and injustice. The book argues that we should approach the ethics of climate engineering via "non-ideal theory," which investigates what justice requires given the fact that many parties have failed to comply with their duty to mitigate greenhouse gas emissions. Specifically, it argues that (...) climate justice should be approached comparatively, evaluating the relative justice or injustice of feasible policies under conditions that are likely to hold within relevant timeframes. Likely near-future conditions include "pessimistic scenarios," in which no available option avoids serious ethical problems. The book contends that certain uses of SRM can be ethically defensible in some pessimistic scenarios. This is the first book devoted to the many ethical issues surrounding climate engineering. (shrink)

Climate ethics has been concerned with polluter pays, beneficiary pays and ability to pay principles, all of which consider climate change as a single negative externality. This paper considers it as a constellation of externalities, positive and negative, with different associated demands of justice. This is important because explicitly considering positive externalities has not to our knowledge been done in the climate ethics literature. Specifically, it is argued that those who enjoy passive gains from climate change owe gains not to (...) the net losers, but to the emitters, just as the emitters owe compensation to the net losers for the negative externality. This is defended by appeal to theoretical virtues and to the social benefits of generating positive externalities, even when those positive externalities are coupled with far greater negative externalities. We call this the Polluter Pays, Then Receives ('PPTR', or 'Peter') Principle. This principle is then applied at two levels in the context of Canada. [Open access]. (shrink)

Behaviour change via monetary investments is a way to fighting climate change. Prior research has investigated the role of climate-change investments using a Collective-Risk-Social-Dilemma game, where players have to collectively reach a target by contributing to a climate fund; failing which they lose their investments with a probability. However, little is known on how variability in the availability of information about players’ investments influences investment decisions in CRSD. In an experiment involving CRSD, 480 participants were randomly assigned to different conditions (...) that differed in the availability of investment information among players. Half of the players possessed a higher starting endowment compared to other players. Results revealed that investments against climate change were higher when investment information was available to all players compared to when this information was available only to a few players or to no one. Similarly, investments were higher among rich players compared to poor players when information was available among all players compared to when it was available only to a few players or to no one. Again, the average investment was significantly greater compared to the Nash investment when investment information was available to all players compared to when this information was available only to a few players or to no one. We highlight some implications of our laboratory experiment for human decision-making against climate change. (shrink)

Integrated assessment models (IAMs) of climate and the economy provide estimates of the social cost of carbon and inform climate policy. With the Nested Inequalities Climate Economy model (NICE) (Dennig et al. PNAS 112:15,827–15,832, 2015), which is based on Nordhaus’s Regional Integrated Model of Climate and the Economy (RICE), but also includes inequalities within regions, we investigate the comparative importance of several factors—namely, time preference, inequality aversion, intraregional inequalities in the distribution of both damage and mitigation cost and the damage (...) function. We do so by computing optimal carbon price trajectories that arise from the wide variety of combinations that are possible given the prevailing range of disagreement over each factor. This provides answers to a number of questions, including Thomas Schelling’s conjecture that properly accounting for inequalities could lead the inequality aversion parameter to have an effect opposite to what is suggested by the Ramsey equation. (shrink)