Assessing climate ambition through policy outputs: a comparative measure of 35 major emitters

Abstract Climate ambition flexibly engages with broad policy frameworks of countries, typically referring to the holistic policy efforts in the climate field. However, understanding of cross-national variation in ambition remains limited, owing to conceptual complexity, limited data, and methodological challenges. I propose a comparative measure of ‘climate policy ambition’ based on the combination of depth and breadth of policy outputs. Drawing on this framework, I introduce a new dataset to explore the climate policy ambitions of 35 major emitters (each contributing at least 0.5% of global emissions) from 1990 to 2020. Empirical findings highlight a global rise in ambition after the Paris Agreement, consistently higher ambition exhibited by European countries, and the divergence of intensity levels across policy fields. However, while climate ambition has markedly increased, levels of actual policy performance have not. The observed imbalance between climate ambition and implementation requires stronger mechanisms to integrate ambition into substantive actions.