Supporting the Paris Agreement through international cooperation: potential contributions, institutional robustness, and progress of Glasgow climate initiatives

The study addresses whether and to what extent international cooperative initiatives launched or revamped around COP26 (the “Glasgow initiatives”) can meaningfully contribute to the Paris Agreement’s long-term temperature goals. It examines: (i) the potential 2030 GHG reductions from full implementation of sector targets; (ii) the institutional robustness of these initiatives; and (iii) the extent to which national government signatories have incorporated initiative targets into their post-COP26 NDC updates. The context is mixed: prior analyses highlight potential for significant mitigation if initiatives are fully implemented, but critics note many pledges lack substantive commitment and follow-through, while global GHG emissions remain on trajectories exceeding 2.5 °C. Few studies have explored how countries’ participation in such initiatives relates to their NDCs and long-term targets. This work focuses on 14 major sector initiatives spanning power, industry, transport, land use, and methane, emphasizing the participation and potential impact of national governments.

Past studies suggested considerable mitigation potential from international climate initiatives and partnerships if fully implemented, indicating they could complement UNFCCC processes by mobilizing sectoral action beyond national borders. However, scholarship also criticizes summit-launched pledges for lacking durability and implementation, with transparency and capacity seen as prerequisites for effectiveness among multistakeholder partnerships and transnational initiatives. Research on NDCs and long-term decarbonization plans is extensive, but analyses of countries’ engagement with international cooperative initiatives and integration into NDCs are limited. Work on climate clubs suggests such arrangements may help prevent backsliding more than they increase ambition, underscoring the need to examine both ambition and institutional set-up to gauge credible delivery.

Scope and initiatives: The study assesses 14 sector initiatives launched or updated around COP26, selected for their sectoral GHG focus and prominence in official and independent COP26 summaries. National government participation was compiled from initiative websites (via Internet Archive) for end-November 2021 and end-January 2023. For Glasgow Breakthroughs, sector-specific endorsements were counted (not the umbrella agenda). Participation in 2023 sector ‘priority international actions’ announced at COP27 was also tracked, though scenario analyses assume COP26 sector endorsers remain participants even if not supporting 2023 actions. NDC integration: Updated NDCs (Dec 2021–Jan 2023) were screened via keywords (“Glasgow”, “COP26”, “Breakthrough”, “Global Methane Pledge”, etc.) and manually reviewed for explicit initiative mentions and target incorporation. Emissions scenarios: Two scenarios quantify potential 2030 impacts for 12 initiatives with quantifiable 2030 goals (Hydrogen and Agriculture Breakthroughs excluded as non-quantifiable): - Glasgow Initiatives–Current Signatories (Glasgow-Signatories): assumes all national signatories as of Jan 2023 fully implement 1.5 °C-aligned 2030 sector goals in the initiatives’ focus areas. - Glasgow Initiatives–Global Ambition (Glasgow-Ambition): assumes global roll-out and full delivery of initiatives’ sector goals, estimating the share of the 2030 emissions gap they could fill. Baselines and benchmarks: The BL-NDC scenario (full implementation of unconditional and conditional NDCs and announced targets as of mid-2021) and BM-1.5 scenario (least-cost 1.5 °C-consistent pathway) were constructed using IEA WEO2021 (APS for BL-NDC; NZE for BM-1.5, downscaled to countries using SDS shares where needed) for energy/industry CO2, complemented by sectoral/non-CO2 projections from external sources. Country-level projections were developed for major emitters and for 99 countries in LULUCF, harmonizing LULUCF accounting (per Grassi et al.) and using NGHGI-based updates and cross-checks. Sectoral initiative potentials were calculated as the BL-NDC to BM-1.5 difference in targeted sectors, assuming initiatives collectively span measures embedded in WEO2021 NZE (efficiency, technology and fuel switching, behavior, tailpipe measures), with electricity demand feedbacks accounted for. Rest-of-world sector reductions were proxied by 2019 sectoral emission shares (IEA, PRIMAP-hist). For the land sector under Glasgow-Ambition, projections equal BM-1.5; under Glasgow-Signatories, only signatory countries to the Forests Declaration were adjusted toward net-zero net forest emissions by 2030 where applicable. Institutional robustness: Six indicators were coded from public sources (C-CID database; data cutoff end-July 2023): (i) dedicated staff/secretariat; (ii) transparent governance structure; (iii) transparent budget; (iv) openness of membership; (v) explicit monitoring arrangements; (vi) publications (progress/emissions reporting). Indicators provide minimum evidence of capacity and credibility to progress toward mitigation impacts.

- Participation and sector coverage: Land use exhibits broad participation via the Glasgow Forests Declaration, and the Global Methane Pledge covers ~60% of global methane emissions. Energy and industry initiatives show low coverage; China is largely absent (signed only the Forests Declaration and Breakthrough Hydrogen; not a Global Methane Pledge signatory). Participation is concentrated in high-income countries (G7 and EU), with low uptake among non-G7 G20 members; China and India are signatories to only two and three initiatives respectively as of Jan 2023. - Post-COP26 participation dynamics: Only the Global Methane Pledge saw substantial signatory growth (from 110 to 150 between Nov 2021 and Nov 2022). Many countries that endorsed sectoral Breakthrough goals at COP26 did not endorse 2023 priority actions at COP27 (e.g., USA for power and road transport; Republic of Korea for power, hydrogen, and steel). - Quantified mitigation potential: Global emissions in 2030 are projected at 49 GtCO2e (BL-NDC) versus 33 GtCO2e (BM-1.5), yielding a 16 GtCO2e emissions gap. • Glasgow-Ambition (global roll-out): initiatives could fill about 65% of the gap (≈10 GtCO2e) by 2030, with largest reductions in power, followed by methane, land use, and road transport. • Glasgow-Signatories (current national signatories): initiatives could fill about 4 GtCO2e of the gap (≈25%), reducing 2030 emissions to ~44 GtCO2e (consistent with ~2 °C in 2100, 66% chance). Roughly one quarter of these reductions come from land use via the Forests Declaration. The limited additionality partly reflects that many signatories already had sector targets as ambitious as initiative goals (e.g., PPCA members with low coal reliance). - Integration into NDCs: Among 38 updated NDCs (Dec 2021–Jan 2023), 34 countries had signed at least one initiative; only the UK referenced all initiatives launched at COP26. Others made sparse references: one country mentioned the Glasgow Breakthroughs (Dominica), one the Forests Declaration (Vietnam), one the Global Coal to Clean Power Transition (Vietnam), and four referenced the Global Methane Pledge (including Micronesia, Republic of Korea, and Vietnam). - Institutional robustness: Considerable variation across initiatives. • Data gaps: Little public information on budgets, suggesting transparency gaps (with some exceptions noted via external sources, e.g., US State Department release for methane). • Membership openness: Often explicit, but unclear for International Aviation Climate Ambition Coalition and the Forests Declaration. • Declarative initiatives (International Aviation Climate Ambition Coalition, Forests Declaration, A2Z Coalition) show limited capacity for coordination, implementation, and monitoring; most lack clear monitoring or participation-expansion processes (Clydebank an exception). These account for ~40% of the 4 GtCO2e signatory potential and are unlikely to realize it without institutional development. • More robust initiatives include the Glasgow Breakthroughs (Power, Road Transport, Steel, Hydrogen, Agriculture), PPCA, BOGA, and the Global Methane Pledge, often stewarded by experienced bodies (Clean Energy Ministerial, Mission Innovation). They show clearer governance, secretariats, monitoring, and openness, representing roughly half of the 4 GtCO2e signatory potential. To date, only the Breakthroughs and the Global Methane Pledge report emission reductions.

The analysis shows that while Glasgow initiatives can engage governments and non-state actors across sectors, the current configuration of national signatories and institutional capacities limits near-term impact. Under present participation, initiatives would fill only about a quarter of the 2030 global emissions gap to a 1.5 °C path, even with full delivery, and many initiatives lack sufficient institutional robustness to ensure implementation. Sparse references in post-COP26 NDCs suggest limited translation of international pledges into national commitments. The findings underscore that broadening participation—especially among major emitters—and embedding initiative goals within NDCs as quantifiable domestic targets are critical steps to convert transnational ambition into national policy and measurable reductions. Strengthening governance—through dedicated secretariats, clear roles, monitoring, transparency, and resourcing—would enhance credibility and the likelihood of delivery, particularly for declarative initiatives. More robust initiatives (PPCA, Global Methane Pledge, Glasgow Breakthroughs) have better prospects for real impact, but scaling effects depend on expanded membership and sector-wide implementation. Climate clubs and cooperative initiatives may help prevent policy backsliding among members, contributing to broader governance benefits, but are not, on their own, sufficient to bridge the 2030 gap without deeper integration into national policy frameworks.

This paper systematically assesses the potential 2030 mitigation contributions and institutional robustness of 14 Glasgow sector initiatives and examines their reflection in updated NDCs. Key contributions include: (1) quantification showing that current-signatory implementation could close ~4 GtCO2e (≈25%) of the 2030 emissions gap, while full global roll-out could close ~10 GtCO2e (≈65%); (2) identification of significant institutional robustness variation and transparency gaps; and (3) evidence of limited incorporation of initiative goals into post-COP26 NDCs. Policy recommendations: (i) expand national government participation, particularly among major emitters and G20 members not yet engaged; (ii) integrate initiative goals into enhanced NDCs with quantifiable domestic targets during the 2025 update cycle; and (iii) strengthen institutional arrangements (secretariats, governance, budgets, monitoring, and reporting) and demand credible follow-up, especially for declarative initiatives. Near-term prospects for real mitigation are strongest in the PPCA, Global Methane Pledge, and Glasgow Breakthroughs, provided membership grows and sectoral implementation scales. Future research should track implementation outputs and realized emission outcomes to validate and refine these projections.

- Scope of actors and impacts: The assessment centers on national government participation and territorial emissions, not fully capturing transnational spillovers or contributions from subnational and corporate actors, whose involvement could extend impacts beyond national policies. - Sectoral coverage: Important emitting sectors and financial initiatives outside the 14 Glasgow initiatives (e.g., cement, buildings, GFANZ) were not assessed, potentially omitting additional mitigation pathways. - Stage of impact chain: The study evaluates target ambition and institutional robustness (early stages) rather than implementation, behavioral change, or realized emission outcomes, which require longitudinal tracking. - Membership vs ambition: Non-participation does not equate to low ambition (e.g., South Africa’s JET-P demonstrates substantial decarbonization efforts outside the assessed initiatives). Uncertainties also stem from scenario assumptions (e.g., LULUCF accounting harmonization, treatment of forest goals, and COVID-19/Ukraine impacts beyond the modeling basis).