What Is the Paris Agreement and How Countries Are Actually Measured?

The Agreement That Changed Climate Diplomacy

On December 12, 2015, representatives of 196 countries meeting in Le Bourget, France, reached a consensus that would reshape global climate policy. The Paris Agreement entered into force in November 2016, becoming the most widely ratified environmental treaty in history. It replaced the earlier Kyoto Protocol with a fundamentally different architecture — one that sought to involve every country rather than only developed nations, and that relied on national self-determination rather than top-down binding targets.

The agreement's central goal is to hold the global average temperature increase to well below 2°C above pre-industrial levels, with a further aspiration to limit warming to 1.5°C. These thresholds were chosen based on climate science indicating significantly worse impacts — more severe sea level rise, more frequent extreme weather, more ecosystem disruption — beyond 2°C. The 1.5°C target was pushed hard by small island nations and climate-vulnerable countries who understood that 2°C might represent an existential threat to their territories.

How the Agreement Is Structured

Unlike the Kyoto Protocol, which set legally binding emissions targets for developed countries, the Paris Agreement uses a softer mechanism: each country submits its own climate action plan called a Nationally Determined Contribution (NDC). NDCs specify what each country commits to do on emissions reduction, adaptation to climate impacts, and sometimes climate finance. Crucially, the emission targets within NDCs are not legally binding under international law — countries cannot be penalized under the treaty for missing their own targets.

What is legally binding is the requirement to submit and update NDCs every five years, with each successive NDC expected to represent a progression beyond the previous one. Countries are also legally required to report on their emissions and progress toward their targets through a common transparency framework. The theory is that mandatory transparency and regular updating create a "ratchet mechanism" — a way to increase global ambition over time even without top-down enforcement.

What Are NDCs and What Do They Actually Say?

NDCs vary enormously in structure, ambition, and specificity. Major emitters have submitted plans that cover their most significant emissions sources. The European Union committed to reducing net greenhouse gas emissions by at least 55% below 1990 levels by 2030. The United States (under the Biden administration) pledged a 50–52% reduction below 2005 levels by 2030. China committed to peak its CO2 emissions before 2030 and achieve carbon neutrality by 2060. India pledged to reach net zero by 2070 and expand its non-fossil energy capacity substantially.

These plans differ in their baseline years, coverage of gases, and conditionality — some countries attach conditions to their targets, promising more if they receive international climate finance. Comparing NDCs across countries is therefore genuinely complex. Analysts at organizations like Climate Action Tracker assess each country's plans and rate them on a scale from "critically insufficient" to "1.5°C compatible." As of the mid-2020s, the aggregate of all NDCs submitted puts the world on track for roughly 2.5–3°C of warming — insufficient by the agreement's own standard.

The Measurement and Reporting System

One of the Paris Agreement's most important innovations is its Enhanced Transparency Framework (ETF), which requires all parties to report regularly on their emissions inventories and progress toward their NDCs using standardized methodologies. Under the ETF, countries submit Biennial Transparency Reports (BTRs) starting in 2024. These reports are then subject to technical expert review and a multilateral review process where other countries can ask questions.

The emissions data in these reports follows guidelines from the Intergovernmental Panel on Climate Change (IPCC) for calculating national greenhouse gas inventories. Countries must account for emissions across major sectors — energy, industry, agriculture, land use, and waste — and across different gases (CO2, methane, nitrous oxide, and others), converted to CO2-equivalent using standardized global warming potentials. Developing countries have somewhat more flexibility in their reporting requirements, recognizing different national capacities.

The Global Stocktake

Every five years, the Paris Agreement calls for a Global Stocktake — a comprehensive assessment of collective progress toward the agreement's goals. The first Global Stocktake was completed at COP28 in Dubai in 2023. Its conclusion was sobering: current policies and NDCs fall far short of the trajectory needed to meet the 1.5°C goal, fossil fuel use needs to be phased down rapidly, and climate adaptation support for vulnerable countries remains deeply inadequate.

The Global Stocktake feeds into the next round of NDC submissions, theoretically ratcheting up ambition. Whether this mechanism actually drives sufficient action depends on political will in major emitting countries — something the treaty cannot create by itself. The agreement provides the architecture for ambition escalation, but the fuel must come from domestic politics, economic shifts, and public pressure in each country.

The Finance Question

Climate finance is one of the most contested dimensions of the Paris Agreement. Developed countries originally committed in 2009 to mobilize $100 billion per year by 2020 for developing countries' climate action — a target that was consistently missed and only nominally achieved through creative accounting of loans and private finance in the early 2020s. At COP29 in Baku in 2024, a new finance goal was negotiated, though the adequacy of the amounts and the proportion of grants versus loans remained deeply contested.

For many developing countries, international climate finance is not just a matter of fairness but of feasibility. Countries with limited fiscal space cannot easily fund major clean energy transitions or climate adaptation infrastructure without external support. The loss and damage mechanism, established at COP27 in Sharm el-Sheikh and operationalized at COP28, represents a further financial commitment to help countries already experiencing climate impacts pay for recovery and rebuilding.

• The Paris Agreement requires NDC submission every 5 years, but emission targets are not internationally enforceable
• The Enhanced Transparency Framework standardizes emissions reporting across all countries from 2024 onward
• The Global Stocktake (every 5 years) assesses collective progress and informs the next NDC round
• Aggregate NDCs as of the mid-2020s put the world on track for roughly 2.5–3°C of warming
• Climate finance flows to developing countries remain well below what scientists say is needed

Can the Paris Agreement Succeed?

The Paris Agreement represents a genuine diplomatic achievement: it created a universal framework where none existed and established the principle that every country must act on climate. But its architecture of voluntary, self-determined targets with transparency accountability rather than binding enforcement has inherent limitations. Progress depends on domestic political dynamics in major emitting countries remaining supportive of ambitious climate action — an assumption that recent political shifts have sometimes challenged.

The honest assessment from the scientific community is that the agreement alone is insufficient. Keeping warming below 2°C requires unprecedented speed and scale of economic transformation — energy system decarbonization, land use change, shifts in agriculture and industry — faster than any comparable transformation in history. The Paris Agreement provides the framework; whether humanity fills it with sufficient ambition remains the defining question of the coming decade.