Time Inconsistency and Credibility in Long-Term Climate Policy

The overarching goal of the 2015 Paris Agreement is to limit global mean temperature increases to 1.5 – 2°C by the end of this century as compared to pre-industrial levels (UNFCCC 2015). To achieve this goal, the Paris Agreement asks its Parties to periodically submit “nationally determined contributions” (NDCs), i.e., comparatively short-term climate pledges that contribute to this overall goal, as well as so-called “Long-term Low Emissions and Development Strategies”. In recent years, more than 150 countries have submitted new or updated 2030 mitigation goals in their NDCs, and around 75 countries have also announced long-term strategies such as net-zero emissions pledges. The long-term targets often imply drastic emission reductions of greenhouse gases (GHGs) by the middle of the present century as well as the build-up of negative emissions, such as increased carbon absorption by forests as well as direct air capture combined with carbon capture and storage. How credible are such long-term targets? By comparing rates of GHG reductions implied by country-specific 2030 and 2050 targets, we assess variations in the temporal structure of countries’ climate pledges. We derive indicators of “frontloading” vs. “backloading” in GHG emission reduction policies until the middle of this century and explain why some countries frontload their emission reductions while others backload emission reductions over time. Our statistical analyses show that most countries backload their emissions reductions, which implies (much) steeper emissions reductions in the period 2030-2050 than for the 2015-2030 period. This finding raises fundamental questions about the credibility of long-term strategies since the short-term pledges are already proving hard to comply with. Further, we show that regime corruption correlates strongly with climate policy backloading. This paper provides a novel approach to assess the credibility of countries’ long-term climate policy, based on temporal variations in pledged emissions cuts.