Make or Brake on the Paris Agreement? Accelerating Climate Ambition Trajectories
2026-06-08
Among OECD states with an outsize responsibility for mitigation efforts, there has been substantial variation in climate ambition in their respective Nationally Determined Contributions (NDCs). This variation in climate ambition occurs across states and also over time in subsequent NDC submission cycles. This article is the first to use qualitative comparative analysis to examine the role of ideas, interests, and institutions in shaping climate ambition trajectories across two rounds of NDC submissions. I find that states with low fossil fuel interests and nonleft partisanship can overcome institutional barriers to submit ambitious NDCs and form positive ambition trajectories. Conversely, high fossil fuel interests and nonleft partisanship form the dominant pathway that constrains climate ambition shifts across conferences of the parties. I focus on Japan as an illustrative case study that demonstrates how climate laggards can improve over time and in turn deepen understandings of the domestic changes that drive positive ambition trajectories.