Introduction

Climate change and global income inequality are intimately and inextricably interrelated. Regional income per capita is well correlated with past and present greenhouse gas emissions. Damages from climate change are expected to be far worse in developing countries, many of which have special geographic vulnerabilities (such as tropical climates or low-lying islands) and most of which can ill afford the adaptation measures necessary to fend off climate impacts. International climate negotiations hinge on finding a compromise between philosophical differences of developed and developing countries on the meaning of equity: what determines each country's responsibility in reducing emissions? What determines each country's responsibility in paying for emissions reductions and adaptation measures at home and abroad?

Climate economics models play an important role in this policy debate by quantifying the value of climate damages and abatement costs under various mitigation scenarios. Many of these integrated assessment models (IAMs) offer policy advice in the form of an optimal scenario: a recommended course of action telling us how much emissions should be abated in what time periods to achieve the greatest human wellbeing across the centuries. In a policy debate fraught with differing understandings of right and wrong, the importance of making transparent the ethical assumptions used in these models cannot be overestimated.