Measuring Alignment with National Climate Commitments: A Gap-to-Target Indicator for Kyoto and Paris NDC Cycles

Assessing whether observed emissions remain aligned with national commitments is central to evaluate international climate agreements. Yet consistent comparisons across countries and commitment cycles remain challenging because national targets differ in their formulation, coverage, and accounting rules. To address this gap, we develop an annual Gap-to-Target indicator that relates observed greenhouse gas emissions to the pathway implied by each national commitment. The indicator is applied to 36 countries during the first Kyoto commitment period and to 164 countries across the first two Paris NDC cycles. The results reveal substantial heterogeneity across countries and commitment cycles. Under Kyoto, land-use accounting and transactions in Kyoto units materially affect measured alignment and country rankings. Under the Paris Agreement, jointly considering target ambition and the Gap-to-Target identifies four ambition–alignment groups and clarifies how commitment stringency relates to countries’ positions. Positive gaps are more prevalent under NDC2. Among 122 countries observed in both cycles, 19.7% move from below to above their target-consistent pathways; only 4.9% move in the opposite direction, and 58.2% remain above in both cycles. Estimates also vary across target architectures and alternative BAU specifications. The framework provides an operational basis for tracking climate commitments and investigating the determinants of emissions alignment. The findings further suggest that greater consistency in the formulation, coverage, and reporting of national targets would strengthen comparative assessments and support more effectively targeted climate action.