The Paris Agreement (also called the Paris Accords or Paris Climate Accords) is an international treaty on climate change that was signed in 2016. The treaty covers climate change mitigation, adaptation, and finance. The Paris Agreement was negotiated by 196 parties at the 2015 United Nations Climate Change Conference near Paris, France. As of January 2026, 194 members of the United Nations Framework Convention on Climate Change (UNFCCC) are parties to the agreement. Of the three UNFCCC member states which have not ratified the agreement, the only major emitter is Iran. The United States, the second largest emitter, withdrew from the agreement in 2020, rejoined in 2021, and withdrew again in 2026.
The Paris Agreement has a long-term temperature goal which is to keep the rise in global surface temperature to well below 2 °C (3.6 °F) above pre-industrial levels. The treaty also states that preferably the limit of the increase should only be 1.5 °C (2.7 °F). These limits are defined as averages of the global temperature measured over twenty years.
The lower the temperature increase, the smaller the effects of climate change can be expected. To achieve this temperature goal, greenhouse gas emissions should be reduced as soon as, and by as much as, possible. They should even reach net zero by the middle of the 21st century. To stay below 1.5 °C of global warming, emissions need to be cut by roughly 50% by 2030. This figure takes into account each country's documented pledges. After the Paris Agreement was signed, global emissions continued to rise rather than fall. 2024 was the hottest year on record, with a rise of more than 1.5 °C in global average temperature.
The treaty aims to help countries adapt to climate change effects, and mobilize enough finance. Under the agreement, each country must determine, plan, and regularly report on its contributions. No mechanism forces a country to set specific emissions targets, but each target should go beyond previous targets. In contrast to the 1997 Kyoto Protocol, the distinction between developed and developing countries is blurred, so that the latter also have to submit plans for emission reductions.
The Paris Agreement was opened for signature on 22 April 2016 (Earth Day) at a ceremony inside the UN headquarters in New York City. After the European Union ratified the agreement, sufficient countries had ratified the agreement responsible for enough of the world's greenhouse gases for the agreement to enter into force on 4 November 2016.
World leaders have lauded the agreement. However, there is debate about its effectiveness, with some environmentalists and analysts criticizing it for not being strict enough. While pledges under the Paris Agreement are insufficient for reaching the set temperature goals, there is a mechanism of increased ambition. The Paris Agreement has been successfully used in climate litigation in the late 2010s, forcing countries and oil companies to strengthen climate action.
Aims
The aim of the agreement, as described in Article 2, is to have a stronger response to the danger of climate change; it seeks to enhance the implementation of the United Nations Framework Convention on Climate Change through:
(a) Holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change;
(b) Increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience and low greenhouse gas emissions development, in a manner that does not threaten food production;
(c) Making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development.
Countries furthermore aim to reach "global peaking of greenhouse gas emissions as soon as possible".
Development
Lead-up
The UN Framework Convention on Climate Change (UNFCCC), adopted at the 1992 Earth Summit is one of the first international treaties on the topic. It stipulates that parties should meet regularly to address climate change, at the Conference of Parties or COP. It forms the foundation to future climate agreements.
The Kyoto Protocol, adopted in 1997, regulated greenhouse gas reductions for a limited set of countries from 2008 to 2012. The protocol was extended until 2020 with the Doha Amendment in 2012. The United States decided not to ratify the protocol, mainly because of its legally-binding nature. This, and distributional conflict, led to failures of subsequent international climate negotiations. The 2009 negotiations were intended to produce a successor treaty of Kyoto, but the negotiations collapsed and the resulting Copenhagen Accord was not legally binding and did not get adopted universally.
The accord did lay the framework for bottom-up approach of the Paris Agreement. Under the leadership of UNFCCC executive secretary Christiana Figueres, negotiation regained momentum after Copenhagen's failure. During the 2011 United Nations Climate Change Conference, the Durban Platform was established to negotiate a legal instrument governing climate change mitigation measures from 2020. The platform had a mandate to be informed by the Fifth Assessment Report of the IPCC and the work of the subsidiary bodies of the UNFCCC. The resulting agreement was to be adopted in 2015.
Negotiations and adoption
Negotiations in Paris took place over a two-week span, and continued throughout the three final nights. Various drafts and proposals had been debated and streamlined in the preceding year. According to one commentator two ways in which the French increased the likelihood of success were: firstly to ensure that Intended Nationally Determined Contributions (INDCs) were completed before the start of the negotiations, and secondly to invite leaders just for the beginning of the conference.
The negotiations almost failed because of a single word when the US legal team realized at the last minute that "shall" had been approved, rather than "should", meaning that developed countries would have been legally obliged to cut emissions: the French solved the problem by changing it as a "typographical error". At the conclusion of COP21 (the 21st meeting of the Conference of the Parties), on 12 December 2015, the final wording of the Paris Agreement was adopted by consensus by the 195 UNFCCC participating member states and the European Union. Nicaragua indicated they had wanted to object to the adoption as they denounced the weakness of the agreement, but were not given a chance. In the agreement the members promised to reduce their carbon output "as soon as possible" and to do their best to keep global warming "to well below 2 degrees C" (3.6 °F).
Signing and entry into force
The Paris Agreement was open for signature by states and regional economic integration organizations that are parties to the UNFCCC (the convention) from 22 April 2016 to 21 April 2017 at the UN Headquarters in New York. Signing of the agreement is the first step towards ratification, but it is possible to accede to the agreement without signing. It binds parties to not act in contravention of the goal of the treaty. On 1 April 2016, the United States and China, which represent almost 40% of global emissions confirmed they would sign the Paris Climate Agreement. The agreement was signed by 175 parties (174 states and the European Union) on the first day it was opened for signature. As of January 2026, 194 states and the European Union have signed the agreement.
The agreement would enter into force (and thus become fully effective) if 55 countries that produce at least 55% of the world's greenhouse gas emissions (according to a list produced in 2015) ratify or otherwise join the treaty. Alternative ways to join the treaty are acceptance, approval or accession. The first two are typically used when a head of state is not necessary to bind a country to a treaty, whereas the latter typically happens when a country joins a treaty already in force. After ratification by the European Union, the agreement obtained enough parties to enter into effect on 4 November 2016.
Both the EU and its member states are individually responsible for ratifying the Paris Agreement. A strong preference was reported that the EU and its 28 member states ratify at the same time to ensure that they do not engage themselves to fulfilling obligations that strictly belong to the other, and there were fears by observers that disagreement over each member state's share of the EU-wide reduction target, as well as Britain's vote to leave the EU might delay the Paris pact. However, the EU deposited its instruments of ratification on 5 October 2016, along with seven EU member states.
Parties
Countries that have ratified or acceded
The EU and 194 states, totalling over 98% of greenhouse gas emissions, have ratified or acceded to the agreement. The only countries which have not ratified are some greenhouse gas emitters in the Middle East: Iran with 2% of the world total being the largest. Libya and Yemen have also not ratified the agreement. Eritrea is the latest country to ratify the agreement, on 7 February 2023.
Article 28 enables parties to withdraw from the agreement after sending a withdrawal notification to the depositary. Notice can be given no earlier than three years after the agreement goes into force for the country. Withdrawal is effective one year after the depositary is notified.
United States withdrawal, readmittance, and rewithdrawal
On 4 August 2017, the Trump administration delivered an official notice to the United Nations that the United States intended to withdraw from the Paris Agreement as soon as it was eligible to do so. The notice of withdrawal could not be submitted until the agreement was in force for three years for the US, on 4 November 2019. The US government deposited the notification with the secretary-general of the United Nations and officially withdrew one year later on 4 November 2020.
President Joe Biden signed an executive order on his first day in office, 20 January 2021, to re-admit the United States into the Paris Agreement. Following the 30-day period set by Article 21.3, the US was readmitted to the agreement. United States climate envoy John Kerry took part in virtual events, saying that the US would "earn its way back" into legitimacy in the Paris process. United Nations secretary-general António Guterres welcomed the return of the United States as restoring the "missing link that weakened the whole".
On 20 January 2025, President Donald Trump signed an executive order again withdrawing the US from the agreement. The withdrawal went into effect on 27 January 2026.
Content
Structure
The Paris Agreement is a short agreement with 16 introductory paragraphs and 29 articles. It contains procedural articles (covering, for example, the criteria for its entry into force) and operational articles (covering, for example, mitigation, adaptation and finance). It is a binding agreement, but many of its articles do not imply obligations or are there to facilitate international collaboration. It covers most greenhouse gas emissions, but does not apply to international aviation and shipping, which fall under the responsibility of the International Civil Aviation Organization and the International Maritime Organization, respectively.
The Paris Agreement has been described as having a bottom-up structure, as its core pledge and review mechanism allows nations to set their own nationally determined contributions (NDCs), rather than having targets imposed top down. Unlike its predecessor, the Kyoto Protocol, which sets commitment targets that have legal force, the Paris Agreement, with its emphasis on consensus building, allows for voluntary and nationally determined targets. The specific climate goals are thus politically encouraged, rather than legally bound. Only the processes governing the reporting and review of these goals are mandated under international law. This structure is especially notable for the United States – because there are no legal mitigation or finance targets, the agreement is considered an "executive agreement rather than a treaty". Because the UNFCCC treaty of 1992 received the consent of the US Senate, this new agreement does not require further legislation.
Another key difference between the Paris Agreement and the Kyoto Protocol is their scope. The Kyoto Protocol differentiated between Annex-I, richer countries with a historical responsibility for climate change, and non-Annex-I countries, but this division is blurred in the Paris Agreement as all parties are required to submit emissions reduction plans. The Paris Agreement still emphasizes the principle of Common but Differentiated Responsibility and Respective Capabilities – the acknowledgement that different nations have different capacities and duties to climate action – but it does not provide a specific division between developed and developing nations.
Nationally determined contributions
Countries determine themselves what contributions they should make to achieve the aims of the treaty. As such, these plans are called nationally determined contributions (NDCs). Article 3 requires NDCs to be "ambitious efforts" towards "achieving the purpose of this Agreement" and to "represent a progression over time". The contributions should be set every five years and are to be registered by the UNFCCC Secretariat. Each further ambition should be more ambitious than the previous one, known as the principle of progression. Countries can cooperate and pool their nationally determined contributions. The Intended Nationally Determined Contributions pledged during the 2015 Climate Change Conference are converted to NDCs when a country ratifies the Paris Agreement, unless they submit an update.
The Paris Agreement does not prescribe the exact nature of the NDCs. At a minimum, they should contain mitigation provisions, but they may also contain pledges on adaptation, finance, technology transfer, capacity building and transparency. Some of the pledges in the NDCs are unconditional, but others are conditional on outside factors such as getting finance and technical support, the ambition from other parties or the details of rules of the Paris Agreement that are yet to be set. Most NDCs have a conditional component.
While the NDCs themselves are not binding, the procedures surrounding them are. These procedures include the obligation to prepare, communicate and maintain successive NDCs, set a new one every five years, and provide information about the implementation. There is no mechanism to force a country to set a NDC target by a specific date, nor to meet their targets. There will be only a name and shame system or as János Pásztor, the former U.N. assistant secretary-general on climate change, stated, a "name and encourage" plan.