Fixing Paris: a comprehensiveness and long-term climate-strategy assessment of UNFCCC COP decisions post 2015

The Paris Agreement of 2015 represented a landmark achievement in international climate governance, yet scholarly assessment reveals significant structural shortcomings that have necessitated progressive elaboration through subsequent Conferences of the Parties (COPs). Existing literature has assessed UNFCCC effectiveness either chronologically or by isolated policy area, with no study having systematically evaluated post-Paris COP decisions as Long-Term Climate Strategies (LTCSs) across the full range of UNFCCC functional domains. This study addresses that gap by offering the first comprehensive cross-COP assessment of decision comprehensiveness from COP21 through COP30. Framing COP cover decisions as multilateral LTCSs, this study adapts Abeysinghe’s (2020) seven success factors for national LTCS assessment into a five-factor evaluative framework applicable to the multilateral governance plane, mapped onto core UNFCCC functional domains. A weighted binary multi-criteria analysis (MCA) is applied to official COP and CMA decisions from COP21 through COP30, sourced from the UNFCCC Secretariat, assigning scores of 0 (no material advancement) or 1 (material advancement) per domain under equal weighting, yielding a comprehensiveness score for each COP session. Results reveal mixed progress across the post-Paris regime. COP21 and COP24 recorded the highest comprehensiveness scores (100% and 91.43%, respectively), reflecting their roles as foundational rule-setting conferences. COP25 recorded the lowest score (22.86%), marking a significant political regression. The Glasgow Climate Pact (COP26) achieved a 77.14% comprehensiveness score, with notable advances in operationalizing market mechanisms, formalizing loss and damage, and advancing adaptation financing, yet persistent shortcomings in aggregate mitigation ambition and financial commitments. Post-Glasgow conferences (COP27–COP30) exhibited a shift toward implementation-oriented consolidation without producing corresponding improvements in emission-reduction outcomes. These findings demonstrate that institutional sophistication within the post-Paris regime has not translated proportionally into comprehensiveness of substantive decisions, with mitigation ambition and finance credibility remaining the regime’s principal structural constraints. The ratchet mechanism emerges as the most consistently operative feature of the Paris architecture, while progress on differentiation and market mechanisms has remained episodic and contingent on negotiating dynamics rather than incremental regime-building. The Glasgow Climate Pact functioned as a structural reset that elevated baseline comprehensiveness for subsequent conferences, though this improvement proved contingently vulnerable, as evidenced by COP27’s score. These findings carry direct implications for COP31 agenda-setting: delivering on mitigation ambition requires both credible financial commitments to restore reciprocity-based trust among developing country Parties and deliberate coalition-building to counteract consensus-based obstruction by high-emitting states.