Paris Agreement
The Paris Agreement (December 2015) is the global climate framework. 195 countries plus the EU have signed; almost all have ratified. The agreement commits parties to hold warming 'well below 2°C' and pursue 1.5°C. Each country sets its own Nationally Determined Contribution (NDC) — there is no top-down emissions allocation. Current NDCs put the world on roughly 2.5–2.7°C of warming.
Key insights
Bottom-up rather than top-down
Pre-Paris attempts (Kyoto Protocol 1997) used top-down emissions caps and failed politically — the US never ratified, developing countries had no targets. Paris reversed the model: each country submits its own pledge ('Nationally Determined Contribution'), reviewed every 5 years. This makes participation universal but enforcement weak — there are no penalties for missing targets, only 'name-and-shame' transparency.
The ratchet mechanism in theory and practice
Each successive NDC is supposed to be more ambitious than the last. The first NDCs (2015) put the world on ~3.6°C. Updated 2020-21 NDCs improved this to ~2.7°C. The 2025 NDC round (due before COP30 in Brazil) is critical — countries need significantly stronger pledges to align with 1.5°C. As of mid-2024, only a minority have submitted updated NDCs; most are late.
Climate finance is the contested core
The $100B/year climate finance pledge (Copenhagen 2009, reaffirmed Paris) for developing countries was finally met in 2022. The new 'NCQG' (New Collective Quantified Goal) at COP29 (2024) raised the figure to $300B/year by 2035 — far below the $1.3T/year that developing countries argue is needed. Climate finance is the central political constraint on developing-country NDC ambition: weak finance, weak commitments.
Implied 2100 warming under different scenarios
°C above pre-industrial, IPCC pathways and tracker analyses
Key Finding: Pledges have improved but remain well above the 1.5°C target. The gap between current policies and target ambition is now the central political problem.
Remaining carbon budget for 1.5°C and 2°C
Gt CO₂ from 2024 onward (IPCC AR6, 50% likelihood)
Key Finding: At current annual emissions of ~37 Gt CO₂, the 1.5°C budget is exhausted in 11 years; the 2°C budget in 29 years.
Methodology & caveats
'Well below 2°C' and 'pursuing efforts toward 1.5°C'
The Paris text is intentionally ambiguous. 'Well below 2°C' suggests ~1.8°C target. 'Pursuing efforts toward 1.5°C' was added at the insistence of small-island states whose territories may not survive 2°C warming. The IPCC 1.5°C special report (2018) showed the meaningful differences between 1.5 and 2°C outcomes — and the post-2018 political conversation has largely treated 1.5°C as the operative goal even though the legal text doesn't require it.
Equity and historical responsibility
Paris pre-supposes that high-historical-emitter countries should do more and provide more finance than low-historical-emitter countries. The implementation is loose — there's no formula. Differentiated responsibilities are operationalized through climate finance commitments, technology transfer, and adaptation funding rather than differentiated emission caps.
Why COP matters anyway
COPs (Conferences of Parties) are theatrical and slow, but they're the only continuous global forum on climate. Major frameworks (Glasgow Climate Pact 2021, Loss and Damage Fund 2022 Sharm el-Sheikh, NCQG 2024 Baku) emerged from COP negotiations even without a Paris-equivalent breakthrough. Critics argue COPs entrench delay; defenders argue they're the only way to keep all parties engaged and accountable.