Does the Paris Agreement's Pledge and Review Process Ratchet up Climate Ambition? A Peer Group Spatial Analysis of Nationally Determined Contributions

The Paris Agreement’s pledge and review process was designed to ramp up ambition through norm-setting and repeated interactions. However, this dynamic remains exogenous to extant analyses of the determinants of climate ambition. To address this gap, this paper aims to answer the question: “Does NDC climate ambition of peer countries influence climate ambition in subsequent rounds?” This paper builds on and aims to contribute to research on the Paris Agreement, the drivers of climate ambition, and the broader literature on soft governance. Through incorporating peer pressure into spatial lags of first-round NDC ambition, spatial regression models are used to analyse the variance of current NDC ambition. We find that climate ambition for peer groups with high geopolitical affinity, similar levels of democracy, and regional similarity converges, whereas development has a negative relationship, leading to divergence. These findings highlight the importance of interaction effects in global climate governance.