Paris Agreement

• 1. Introduction

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  The Paris Agreement was adopted on the 12th of December 2015, inside a conference hall outside Paris, by 195 nations and the European Union. The vote was unanimous, or nearly so. Nicaragua wanted to object, arguing the deal was too weak, but was never given a chance to speak. So the gavel came down on what would become the most widely joined climate treaty in history.

  How did the world get there? For decades, countries had tried and stumbled. A 1997 treaty set firm targets but the United States never ratified it. A 2009 summit in Copenhagen was supposed to produce a successor and instead collapsed, producing an accord that was neither legally binding nor universally accepted. Then a quieter, more patient approach took shape, and Paris became its test.

  What the agreement says, what it actually requires, and whether it is working are three very different questions. The temperature goals written into its text have been crossed in a single calendar year. Countries promised to cut emissions and kept letting them rise. Yet courts have used the agreement to order governments and oil companies to change course. The distance between what Paris promised and what the planet is experiencing is one of the defining tensions of our time.

• 2. The Long Road to Paris

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  The 1992 Earth Summit produced the United Nations Framework Convention on Climate Change, one of the first serious international efforts on the climate question. It established the practice of regular meetings, the Conferences of the Parties, and it created the legal foundation on which everything since has rested.

  The Kyoto Protocol of 1997 went further, setting binding emissions targets for wealthier nations covering the period 2008-2012. The United States decided not to ratify it, citing its legally binding nature as the main obstacle. That refusal, combined with recurring disputes over which countries bore what responsibility, poisoned subsequent negotiations. The 2009 summit in Copenhagen was intended to replace Kyoto with something broader, and the collapse of those talks left climate diplomacy in an uncertain place.

  Christiana Figueres, executive secretary of the UNFCCC, led the effort to rebuild momentum after Copenhagen's failure. At the 2011 United Nations Climate Change Conference in Durban, negotiators established what became known as the Durban Platform: a mandate to create a new legal instrument governing climate action from 2020 onward, with the resulting agreement to be adopted in 2015. That mandate set the clock running toward Paris, and Figueres would be among those credited when the clock stopped on a deal.

• 3. How the Deal Was Made

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  Negotiations in Paris ran for two weeks and then kept going through the three final nights. The French hosts had made two decisions that would later be credited with keeping the talks on track. They ensured that countries submitted their intended contributions before the conference began, removing one major pressure point. They also invited world leaders only to the opening, so heads of state could generate political momentum without being present to complicate the detailed drafting that followed.

  The agreement nearly unraveled over a single word. At the last minute, the American legal team noticed that the word "shall" had survived into a provision requiring developed countries to cut emissions, which would have created a legally binding obligation. The French presidency resolved the problem by reclassifying it as a typographical error and swapping in "should". The distinction mattered enormously. Under United States law, a treaty with binding mitigation targets would have required Senate ratification. Without binding targets, the agreement could take effect as an executive agreement, bypassing that obstacle entirely.

  When the final text was adopted on the 12th of December 2015, it reflected this careful architecture. The specific climate goals in each country's plan are, as the agreement puts it, politically encouraged rather than legally bound. Only the reporting and review procedures carry legal force.

• 4. What the Agreement Actually Says

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  Article 2 sets out three aims: hold the global average temperature rise to well below 2 degrees Celsius above pre-industrial levels, pursue efforts to limit that rise to 1.5 degrees, and make financial flows consistent with low-emissions development. The 1.5-degree figure was a major concession to small island states and least-developed nations for whom the difference between 1.5 and 2 degrees is not academic but existential.

  Each country designs its own plan, called a nationally determined contribution, or NDC. Article 3 requires these to be ambitious, to represent a progression over time, and to be updated every five years. The UNFCCC Secretariat registers them. There is no mechanism to compel a country to set any specific target. What János Pásztor, a former UN assistant secretary-general on climate change, described as a "name and encourage" plan is the primary enforcement tool.

  The agreement does not cover international aviation or shipping, which fall under separate international bodies. It does include a framework for carbon trading between countries, known as internationally transferred mitigation outcomes, or ITMOs, with rules finalized at COP26 in Glasgow in 2021. Switzerland is, as of the available record, the only country actively purchasing ITMOs, with deals signed with Peru, Ghana, Senegal, Georgia, Dominica, Vanuatu, Thailand, and Ukraine.

  Loss and damage, meaning the harms that cannot be adapted away, received recognition as a separate pillar of the agreement, pushed there by the Alliance of Small Island States and least-developed countries. The United States resisted this framing, concerned it might create new liability. The final text calls for averting, minimizing, and addressing loss and damage but explicitly states the provision cannot be used as a basis for liability claims.

• 5. The United States and the Agreement

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  On the 1st of April 2016, the United States and China together confirmed they would sign the Paris Agreement. The two countries at that point represented almost 40 percent of global emissions, and their joint announcement signaled that the deal would have real weight. The agreement entered into force on the 4th of November 2016, after the European Union ratified and enough parties representing enough emissions had joined.

  Less than a year later, on the 4th of August 2017, the Trump administration notified the United Nations of its intent to withdraw. The agreement's own rules set a waiting period: a country could not submit a withdrawal notification until the treaty had been in force for three years in that country, meaning the earliest possible submission date for the United States was the 4th of November 2019. The withdrawal formally took effect one year after that, on the 4th of November 2020.

  President Joe Biden signed an executive order on the 20th of January 2021, his first day in office, to rejoin the agreement. Climate envoy John Kerry said publicly that the country would "earn its way back" into legitimacy in the Paris process. UN secretary-general António Guterres described the return as restoring the "missing link that weakened the whole."

  On the 20th of January 2025, President Donald Trump signed an executive order withdrawing the United States again. That withdrawal went into effect on the 27th of January 2026. The United States, the second largest emitter of greenhouse gases after China, has now left the agreement twice.

• 6. The Gap Between Promise and Reality

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  After the agreement was signed, global emissions kept rising. In 2021, a study using a probabilistic model found that emissions reductions would need to increase by 80 percent beyond the existing NDCs to likely meet the 2-degree upper target. The same study estimated a 5-26 percent probability of staying below 2 degrees of warming even if NDCs were met and continued after 2030.

  A pair of studies published in Nature found that as of 2017, none of the major industrialized nations were implementing the policies they had pledged, and none had met their pledged emission reduction targets. Even if every pledge had been fulfilled, the combined commitments as of 2016 would not have kept temperature rise well below 2 degrees.

  The 2021 Production Gap report found that governments were still planning to produce 110 percent more fossil fuels in 2030 than the 1.5-degree limit would allow, including 240 percent more coal, 57 percent more oil, and 71 percent more gas. In September 2021, the Climate Action Tracker estimated that current policies pointed to global emissions doubling above the 2030 target level, a gap of 20-23 gigatonnes of carbon dioxide equivalent.

  Only the Gambia's emissions were assessed to be at the level required by the Paris Agreement. Countries including Iran, Russia, Saudi Arabia, Singapore, and Thailand were criticized for policies consistent with roughly 4 degrees of warming if applied globally. The first global stocktake report, released in September 2023, carried both genuine good news and a stark warning: the expected 2100 temperature rise had fallen from 3.7-4.8 degrees in 2010 to 2.4-2.6 degrees by COP27, but the world remained far from 1.5 degrees, and global emissions had not yet peaked.

• 7. The Courts Step In

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  State of the Netherlands v. Urgenda Foundation began before the Paris Agreement existed, filed after the Dutch government reduced its planned emissions reductions for 2030. A court ruled against the government in 2015, requiring it to maintain its planned reductions. The Dutch Supreme Court upheld that ruling in 2019, finding that the government had violated human rights under Dutch law and the European Convention on Human Rights. The 2-degree temperature target from the Paris Agreement formed part of the legal basis for that judgment.

  In Germany, the agreement's goals, enshrined in German law, formed part of the argumentation in Neubauer et al. v. Germany, in which the court ordered Germany to reconsider its climate targets.

  In May 2021, the district court of The Hague ruled against Royal Dutch Shell in Milieudefensie et al. v. Royal Dutch Shell, ordering the company to cut its global emissions by 45 percent from 2019 levels by 2030. The court found Shell was in violation of human rights. This case was considered the first major application of the Paris Agreement toward a corporation.

  On the 4th of July 2022, the Supreme Federal Court of Brazil recognized the Paris Agreement as a human rights treaty, ruling it should supersede national law. That same month, the United Nations Human Rights Council passed a resolution linking the right to stop climate change with the right to food. As James Hansen, a former NASA scientist, put it, the agreement consists largely of promises and aims rather than firm commitments, but the courts have begun to treat those promises as something that carries legal consequence.

• 8. Where the Temperature Stands

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  The Paris Agreement required countries to pursue efforts to limit warming to 1.5 degrees Celsius above pre-industrial levels but did not define what "pre-industrial" meant. In 2018, the IPCC filled that gap in a special report titled "Global Warming of 1.5 degrees C," setting the reference period as 1850-1900 and defining the warming as a 30-year global average of combined land air and ocean surface temperatures.

  Using that methodology, the 2017 30-year average stood at about 1.03 degrees, and the IPCC predicted the 1.5-degree level would be crossed around 2040. As of 2024, applying the same methodology, the crossing was projected to occur sometime in 2029. That projection may itself be optimistic: the warming trend since 2017 suggests the IPCC's original figure for that year was underestimated by about 0.1 degrees.

  2024 was the hottest year on record, with the global average temperature rising more than 1.5 degrees for a single calendar year. Scientists have suggested that 2024 may mark the beginning of a 20-year period that will establish a sustained average above 1.5 degrees. The agreement's own stocktake process identified 2025 as the year by which global emissions need to peak to hold warming to 1.5 degrees. That window is now closed.