What Is the Paris Agreement?

The Paris Agreement is a legally binding international treaty on climate change, adopted by 196 Parties at the twenty-first Conference of the Parties to the United Nations Framework Convention on Climate Change in Paris on 12 December 2015 and in force since 4 November 2016. Its central objective is to hold the increase in global average temperature to well below 2 degrees Celsius above pre-industrial levels while pursuing efforts to limit the increase to 1.5 degrees. Alongside that mitigation target, the treaty sets goals for adaptation and for aligning financial flows with low-emission, climate-resilient development.

The agreement broke with the architecture of the 1997 Kyoto Protocol, which assigned binding emission targets to a listed group of industrialized countries. Paris instead applies to all Parties and makes the substance of each country's target self-determined, with the binding obligations attaching to process: submitting a target, reporting progress against it, and participating in periodic collective review. That design choice is what allowed near-universal participation, and it is also the source of most criticism of the treaty's stringency. The two treaties are legally separate instruments adopted under the same framework convention, and Kyoto was never repealed: its second commitment period ran until the end of 2020, overlapping the first years of the Paris regime.

Nationally Determined Contributions

Each Party sets out its climate plan in a nationally determined contribution, or NDC, which states an emissions target and describes the policies intended to meet it. NDCs are submitted and updated every five years, and Article 4 requires each successive submission to represent a progression beyond the previous one, a ratchet mechanism intended to close the gap between pledges and the temperature goal over time. The 2025 round called for targets extending to 2035. NDCs vary widely in form: some express absolute economy-wide reduction targets against a base year, others use intensity targets, deviation from a business-as-usual baseline, or conditional pledges contingent on international finance. Analyses of the submitted contributions consistently find aggregate ambition short of what a 1.5 degree pathway requires.

Transparency, Accounting, and the Global Stocktake

Because targets are self-set, the credibility of the regime rests on measurement. Article 13 establishes an enhanced transparency framework under which Parties submit national greenhouse gas inventories and biennial transparency reports, prepared using Intergovernmental Panel on Climate Change methodologies and subject to technical expert review. That machinery drives demand for atmospheric monitoring networks, satellite observation of carbon dioxide and methane plumes, activity data collection across energy and land-use sectors, and uncertainty quantification in inventory estimates. Every five years the global stocktake assesses collective progress and feeds the result back into the next round of NDCs. The first stocktake concluded in 2023 and called on countries to transition away from fossil fuels in energy systems and to triple renewable capacity by 2030.

Finance, Markets, and Adaptation

Article 9 obliges developed countries to provide financial resources to developing countries for mitigation and adaptation, with a collective quantified goal periodically renegotiated. Article 6 provides for cooperative approaches, including internationally transferred mitigation outcomes and a centralized crediting mechanism, with rules designed to prevent the same reduction being counted twice. Article 7 establishes a global goal on adaptation, and a separate fund addressing loss and damage from climate impacts was operationalized after the treaty's adoption.

Applications

The Paris Agreement shapes technical work in a range of fields, including:

• National greenhouse gas inventory and emissions accounting systems
• Satellite and ground-based atmospheric monitoring
• Power system planning and renewable energy integration
• Carbon market design and registry infrastructure
• Industrial decarbonization and process electrification
• Climate risk assessment for infrastructure and finance
• Integrated assessment and Earth system modeling