Person:

Aldy, Joseph

A natural outcome of the emerging pledge and review approach to international climate change policy is the interest in comparing mitigation efforts among countries. Domestic publics and stakeholders will have an interest in knowing if peer countries are undertaking (or planning to undertake) comparable efforts in mitigating their greenhouse gas emissions. Moreover, if the aggregate efforts are considered inadequate in addressing the risks posed by climate change, then this will likely prompt a broader interest in identifying those countries where greater efforts are arguably warranted based on comparison with their peers. Both assessments require metrics of efforts and comparisons among countries. We propose a framework for such an exercise, drawing from a set of principles for designing and implementing informative metrics. We present a template for organizing metrics on mitigation efforts, for both ex ante and ex post review. We also provide preliminary assessments of efforts along emissions, price, and cost metrics for post-2020 climate policy contributions by China, the European Union, Russia, and the United States. We close with a discussion of the role of academics and civil society in promoting transparency and facilitating the evaluation and comparison of efforts.

A key element in the emerging international architecture will be practical mechanisms to compare domestic efforts to mitigate global climate change. How do countries decide whether and to what degree pledges by their peers – often expressed in different forms that stymie obvious apples-to-apples comparison – are sufficient to justify their own actions now and more ambitious actions in the future? We describe a number of desirable features of metrics that might be used for ex ante comparisons of proposed pledges and ex post assessments of subsequent actions delivering on those pledges. Such metrics should be comprehensive, measurable, and universal. In practice, however, no single metric has all these features. We suggest using a collection of metrics to characterise and compare mitigation efforts, akin to employing a suite of economic statistics to illustrate the health of the macroeconomy. We illustrate the application of a suite of metrics to several countries’ mitigation pledges (their intended nationally determined contributions in the UN climate talks). In the pledge and review model emerging in the climate change negotiations, participation, compliance, and ambition can be enhanced if this collection of metrics can illustrate comparable actions among peers, both prospectively and retrospectively. The latter, in particular, highlights the need for a well-functioning policy surveillance regime.