The Paris Agreement, also known as the Paris Accords or Paris Climate Accords, is an international treaty about climate change that was signed in 2016. The treaty focuses on reducing greenhouse gas emissions, preparing for the effects of climate change, and gathering enough money to support these efforts. The agreement was created by 196 countries during the 2015 United Nations Climate Change Conference held near Paris, France. As of January 2026, 194 members of the United Nations Framework Convention on Climate Change (UNFCCC) have joined the agreement. Among the three UNFCCC member states that have not ratified the agreement, only Iran is a major emitter of greenhouse gases. The United States, the second-largest emitter, left the agreement in 2020, returned in 2021, and left again in 2026.
The Paris Agreement has a long-term goal to keep the rise in global surface temperature well below 2 degrees Celsius (about 3.6 degrees Fahrenheit) above pre-industrial levels. It also aims to limit the increase to 1.5 degrees Celsius (about 2.7 degrees Fahrenheit) if possible. These temperature limits are based on average global temperatures measured over many years.
Smaller temperature increases mean climate change effects will likely be less severe. To reach the temperature goals, greenhouse gas emissions must be reduced as quickly and as much as possible. Emissions should reach net zero by the middle of the 21st century. To stay below 1.5 degrees Celsius of global warming, emissions must be cut by about 50% by 2030. This number considers each country’s reported plans. After the agreement was signed, global emissions continued to rise instead of falling. 2024 was the hottest year on record, with global average temperatures rising more than 1.5 degrees Celsius above pre-industrial levels.
The treaty helps countries prepare for climate change and gather enough money to support these efforts. Under the agreement, each country must decide, plan, and regularly report on its contributions. No rule forces a country to set specific emissions targets, but each target should be more ambitious than the last. Unlike the 1997 Kyoto Protocol, the Paris Agreement does not clearly separate developed and developing countries, so both groups must submit plans to reduce emissions.
The Paris Agreement was opened for signing on April 22, 2016 (Earth Day) at a ceremony in the United Nations Headquarters in New York. After the European Union joined the agreement, enough countries had signed the treaty to meet the required threshold for the agreement to take effect on November 4, 2016.
World leaders have praised the agreement. However, some environmentalists and analysts argue it is not strict enough to achieve its temperature goals. While current pledges under the Paris Agreement are not enough to meet the targets, the agreement includes a process to increase ambition over time. The Paris Agreement has also been used in climate-related legal cases in the late 2010s, leading to stronger climate action by countries and oil companies.
Aims
The goal of the agreement, as explained in Article 2, is to improve the way the world responds to the threat of climate change. It aims to improve how the United Nations Framework Convention on Climate Change is carried out.
Additionally, countries want to achieve the point where global greenhouse gas emissions stop increasing and start to decrease as quickly as possible.
Development
The UN Framework Convention on Climate Change (UNFCCC), created during the 1992 Earth Summit, is one of the first international agreements about climate change. It requires countries to meet regularly at the Conference of Parties (COP) to discuss climate issues. This agreement forms the basis for future climate treaties.
The Kyoto Protocol, created in 1997, required certain countries to reduce greenhouse gas emissions between 2008 and 2012. This agreement was extended until 2020 through the Doha Amendment in 2012. The United States did not ratify the Kyoto Protocol because it required countries to follow legally binding rules. This decision, along with disagreements about how responsibilities should be shared, caused problems in later climate talks. In 2009, talks aimed to create a new agreement to replace Kyoto, but they failed. Instead, the Copenhagen Accord was created, but it was not legally binding and was not accepted by all countries.
The Copenhagen Accord helped set the stage for the Paris Agreement, which uses a bottom-up approach. Under the leadership of UNFCCC executive secretary Christiana Figueres, talks gained momentum after the failure in Copenhagen. At the 2011 United Nations Climate Change Conference, the Durban Platform was created to negotiate a legal agreement about climate change measures starting in 2020. The platform was required to use information from the IPCC’s Fifth Assessment Report and the work of the UNFCCC’s subsidiary groups. The final agreement was planned to be adopted in 2015.
Negotiations for the Paris Agreement took place over two weeks and continued into the final three nights. Many drafts and proposals had been discussed and simplified in the year before. One expert noted that two actions helped increase the chances of success: ensuring that Intended Nationally Determined Contributions (INDCs) were completed before negotiations began, and inviting world leaders only for the opening of the conference.
Negotiations nearly failed because of a single word. At the last moment, the U.S. legal team discovered that the word "shall" had been approved instead of "should," which would have legally required developed countries to cut emissions. The French team solved this by calling it a "typographical error" and changing the word. On December 12, 2015, the final version of the Paris Agreement was approved by all 195 UNFCCC member states and the European Union at COP21. Nicaragua wanted to object because it believed the agreement was too weak, but it was not given the chance. The agreement states that countries will reduce their carbon emissions as soon as possible and work to keep global warming below 2 degrees Celsius (3.6 degrees Fahrenheit).
The Paris Agreement was open for signing by countries and regional groups that are part of the UNFCCC from April 22, 2016, to April 21, 2017, at the UN Headquarters in New York. Signing is the first step toward ratification, but countries can also join the agreement without signing. The agreement requires countries to act in a way that supports the treaty’s goals. On April 1, 2016, the United States and China, which together produce about 40% of the world’s emissions, confirmed they would sign the agreement. On the first day it was open for signing, 175 countries (174 states and the European Union) signed the agreement. As of January 2026, 194 countries and the European Union had signed the agreement.
The agreement will become fully effective if 55 countries that produce at least 55% of the world’s greenhouse gas emissions (as listed in 2015) ratify or join the treaty. Countries can also join through acceptance, approval, or accession. Acceptance and approval are usually used when a country’s head of state is not needed to join a treaty, while accession is used when a country joins a treaty that is already in force. After the European Union ratified the agreement, it met the requirements to make the agreement effective on November 4, 2016.
Both the European Union and its member states must individually ratify the Paris Agreement. It was strongly preferred that the EU and its 28 member states ratify the agreement at the same time to avoid confusion about responsibilities. Concerns existed that disagreements about how to share the EU’s overall emissions reduction goals and the UK’s decision to leave the EU might delay the agreement. However, the EU and seven of its member states submitted their ratification documents on October 5, 2016.
Parties
The European Union and 194 other countries, which together produce more than 98% of the world’s greenhouse gas emissions, have signed and agreed to the Paris Agreement. The only countries that have not signed are some greenhouse gas emitters in the Middle East, including Iran, which produces 2% of the world’s total emissions. Libya and Yemen have also not signed the agreement. Eritrea most recently signed the agreement on February 7, 2023.
Article 28 of the agreement allows countries to leave it after sending a notice to the official keeper of the agreement. This notice can be sent no earlier than three years after the agreement becomes active for the country. A country can only leave the agreement one year after the notice is received.
On August 4, 2017, the Trump administration sent a formal notice to the United Nations stating that the United States, the second-largest greenhouse gas emitter after China, planned to leave the Paris Agreement as soon as it was allowed. The notice could not be submitted until three years after the agreement became active for the United States, which was November 4, 2019. The U.S. government sent the notice to the United Nations secretary-general and officially left the agreement one year later, on November 4, 2020.
On January 20, 2021, President Joe Biden signed an order to rejoin the Paris Agreement on his first day in office. After a 30-day period required by Article 21.3, the United States was readmitted. United States climate envoy John Kerry participated in virtual events, stating the U.S. would "earn its way back" into the agreement. United Nations secretary-general António Guterres welcomed the U.S. return, calling it a step that restored a "missing link" that had weakened the agreement.
On January 20, 2025, President Donald Trump signed an order to leave the agreement again. The withdrawal became effective on January 27, 2026.
Content
The Paris Agreement is a short agreement with 16 introductory paragraphs and 29 articles. It includes procedural articles (such as rules for how the agreement starts being used) and operational articles (such as rules for reducing emissions, adapting to climate change, and providing financial help). The agreement is legally binding, but many of its rules do not require countries to take specific actions. Instead, they help countries work together internationally. The agreement covers most greenhouse gas emissions but does not apply to international aviation or shipping, which are managed by the International Civil Aviation Organization and the International Maritime Organization, respectively.
The Paris Agreement is described as having a bottom-up structure because it allows countries to set their own goals for reducing emissions, called nationally determined contributions (NDCs), rather than having goals set for them by others. Unlike the Kyoto Protocol, which required legally binding targets, the Paris Agreement focuses on building agreement among countries. This means that climate goals are encouraged through political efforts, not legal requirements. Only the rules for reporting and reviewing these goals are required by international law. This structure is especially important for the United States because the agreement does not require legally binding targets for reducing emissions or providing financial help. Since the UNFCCC treaty of 1992 was approved by the U.S. Senate, the Paris Agreement does not need new laws to be passed.
A major difference between the Paris Agreement and the Kyoto Protocol is their scope. The Kyoto Protocol separated countries into two groups: Annex-I countries (richer nations with a history of causing climate change) and non-Annex-I countries. The Paris Agreement does not make this distinction clearly, as all countries are required to submit emissions reduction plans. The Paris Agreement still supports the idea that different nations have different responsibilities and abilities to address climate change, but it does not divide countries into developed and developing groups.
Each country decides what contributions it will make to meet the goals of the agreement. These plans are called nationally determined contributions (NDCs). Article 3 requires NDCs to be "ambitious efforts" that work toward the goals of the agreement and improve over time. Countries must update their NDCs every five years, and these updates must be more ambitious than the previous ones. These updates are registered by the UNFCCC Secretariat. Countries can work together to combine their contributions. When a country ratifies the Paris Agreement, its Intended Nationally Determined Contributions from the 2015 Climate Change Conference become official NDCs, unless the country submits an updated plan.
The Paris Agreement does not specify the exact details of NDCs. At a minimum, NDCs must include actions to reduce emissions, but they may also include goals for adapting to climate change, providing financial help, sharing technology, building capacity, and being transparent. Some parts of NDCs are unconditional, while others depend on factors like receiving financial or technical support, the actions of other countries, or details of the Paris Agreement that are still being worked out. Most NDCs include some conditional parts.
Although NDCs themselves are not legally binding, the processes around them are. Countries must prepare, share, and update their NDCs every five years. They must also provide information about how they are implementing their goals. There is no rule that forces a country to set a NDC by a certain date or to meet its goals. Instead, the agreement uses a system where countries are named and encouraged to improve their efforts, as described by János Pásztor, a former U.N. assistant secretary-general on climate change.
Under the Paris Agreement, countries must improve their goals every five years. To help with this, the agreement created the Global Stocktake, which checks progress. The first review was in 2023. The results of this review are used to help countries update their NDCs. The Talanoa Dialogue in 2018 was an example of this process. After a year of discussion, a report was published and a call for action was made, but countries did not increase their goals afterward.
The Global Stocktake is part of the Paris Agreement's effort to increase the ambition of emissions reductions over time. In 2014, experts said that the NDCs would not be enough to keep global temperatures below 2°C, so the Global Stocktake brings countries together to review how their NDCs must improve to reflect their highest possible efforts. While increasing the ambition of NDCs is a major goal of the Global Stocktake, it also evaluates efforts beyond emissions reductions, such as adaptation, climate finance, and technology development and sharing.
On November 30, 2023, the United Nations Climate Change Conference (COP28) began in Dubai with renewed calls for stronger climate action.
Article 6 is one of the most important parts of the Paris Agreement. It outlines ways countries can work together to reduce emissions. This helps create a framework for a global carbon market. Article 6 is the only major part of the agreement that has not yet been fully decided. Negotiations in 2019 did not reach an agreement, but the topic was resolved during the 2021 COP26 in Glasgow. A system called "corresponding adjustment" was created to prevent double counting of emission reductions.
Paragraphs 6.2 and 6.3 set up a system for the international transfer of mitigation outcomes (ITMOs). The agreement allows countries to use emissions reductions from other countries toward their NDCs. This requires linking carbon emissions trading systems, as emissions reductions must not be counted twice. One country would record the reduction as a gain, and the other would record it as a loss, known as "corresponding adjustment." Because NDCs and domestic carbon trading systems vary, ITMOs provide a way for countries to connect their systems under the UNFCCC. This also encourages countries to develop systems for managing emissions, as they may need to track carbon units to use cost-effective methods for meeting their NDCs.
So far, Switzerland is the only country that has signed agreements to buy ITMOs. Switzerland has made deals with Peru, Ghana, Senegal, Georgia, Dominica, Vanuatu, Thailand, and Ukraine.
Paragraphs 6.4–6.7 describe a system to help reduce greenhouse gases and support sustainable development. This system is not yet officially named but is sometimes called the Sustainable Development Mechanism (SDM). The SDM is the successor to the Clean Development Mechanism, which was used under the Kyoto Protocol to help countries reduce emissions together.
The SDM is expected to work similarly to the Clean Development Mechanism, with the goals of reducing global greenhouse gas emissions and supporting sustainable development. While the details of the SDM are not yet decided, it is expected to have similarities and differences compared to the Clean Development Mechanism.
Implementation
The Paris Agreement is carried out through each country's own plans. It includes improving energy efficiency to use less energy for the same amount of goods and services worldwide. Implementation also needs to reduce the use of fossil fuels and increase the use of sustainable energy quickly. Emissions are decreasing fast in the electricity sector, but not as much in buildings, transportation, and heating. Some industries are hard to make carbon-free, so removing carbon dioxide from the air might be needed to reach net zero emissions. In a 2022 report, the IPCC said innovation and technology changes, along with changes in how people use and make products, are needed to meet the Paris Agreement goals.
To keep global warming below 1.5°C, emissions must be cut by about half by 2030. This total includes all countries' individual plans to reduce emissions. By the middle of the century, carbon dioxide emissions must reach zero, and total greenhouse gases must be net zero shortly after that.
There are challenges to following the agreement. Some countries have trouble getting the money needed for projects that reduce carbon emissions. Climate finance is spread out, making it harder to invest. Another problem is that governments and other organizations often lack the ability to carry out policies. Clean technology and knowledge are not always shared with countries or areas that need them. In December 2020, the former leader of COP 21, Laurent Fabius, said the Paris Agreement could be improved by creating a Global Pact for the Environment. This pact would outline the environmental rights and responsibilities of governments, individuals, and businesses.
Specific topics of concern
The Paris Agreement's ability to meet its climate goals is being discussed by experts. Many believe it is not enough to keep global temperatures from rising more than 1.5°C. Some details of the agreement are still being worked out, so it may be too early to fully judge its success. A 2020 report by the United Nations Environment Programme said that if current climate plans are followed, global temperatures could rise by more than 3°C by the end of the 21st century. Newer goals to reach net zero emissions were not included in the Nationally Determined Contributions (NDCs) of countries, but they could help reduce temperatures by an additional 0.5°C.
The initial promises made by countries are not enough to meet the Paris Agreement's targets. If these goals are not met, more and faster actions to reduce emissions would be needed, but at a higher cost. There is also a gap between what countries have promised in their NDCs and what they actually do. About one-third of the difference between the lowest cost of reducing emissions and actual reductions could be closed by following existing pledges. A pair of studies in Nature found that in 2017, none of the major industrialized nations were following the policies they had promised, and none had met their emission reduction goals. Even if all countries had met their pledges by 2016, the combined efforts would not have kept global warming "well below 2°C."
A 2021 study using a probabilistic model said that emissions reductions would need to increase by 80% beyond current NDCs to likely meet the 2°C target of the Paris Agreement. The chance of major emitters meeting their NDCs without such an increase is very low. The study also estimated that if current trends continue, the probability of keeping global warming below 2°C is 5–26%, even if all signatories meet their NDCs and continue them after 2030.
As of 2020, there is limited scientific research on how well the Paris Agreement is working in areas like helping countries build capacity and adapt to climate change, even though these topics are important parts of the agreement. Available research is mixed in its conclusions about loss and damage, and adaptation efforts.
According to the stocktake report, the agreement has had an effect: in 2010, the expected temperature rise by 2100 was 3.7–4.8°C, but at COP 27, it was reduced to 2.4–2.6°C. If all countries meet their long-term pledges, the temperature rise could be 1.7–2.1°C. However, the world is still far from the goal of limiting warming to 1.5°C. To achieve this, emissions must peak by 2025. Recent data from 2024 shows that Earth has likely entered a 20-year period where the average warming will reach 1.5°C. Some studies suggest that the global mean temperature may have already exceeded 1.5°C in 2024.
The Paris Agreement has influenced the focus of the IPCC's reports. Before the agreement, IPCC reports discussed temperatures above and below 2°C roughly equally. However, in the 6th assessment report, after the Paris Agreement, less than 20% of temperature mentions were above 2°C, and nearly 50% focused on 1.5°C.
In September 2021, the Climate Action Tracker estimated that current policies would lead to global emissions doubling above the 2030 target level. The gap is 20–23 Gt CO2e. Countries like Iran, Russia, Saudi Arabia, Singapore, and Thailand have been criticized for not doing enough to meet the agreement's requirements. If current policies are widely followed, these countries could contribute to a 4°C warming. Only the Gambia's emissions are at the level required by the Paris Agreement. Models predicted that without necessary measures by autumn 2021, global temperatures would rise by 2.9°C. With the implementation of Paris Agreement pledges, temperatures would rise by 2.4°C, and with every zero-emission target reached, the rise would be 2.0°C.
The Production Gap 2021 report states that governments still plan to produce 110% more fossil fuels in 2030 than the 1.5°C limit allows, including 240% more coal, 57% more oil, and 71% more gas.
In September 2023, the first global stocktake report on the Paris Agreement's implementation was released. The report said that the agreement has had a significant effect: in 2010, the expected temperature rise by 2100 was 3.7–4.8°C, but at COP 27, it was 2.4–2.6°C. If all countries meet their long-term pledges, the rise could be 1.7–2.1°C. However, the world is still far from limiting warming to 1.5°C. To meet this goal, global emissions must peak by 2025. While some countries have already peaked, global emissions have not.
Developed countries reaffirmed their commitment to provide $100 billion annually in climate finance by 2020 and agreed to continue this until 2025. This funding supports mitigation and adaptation efforts in developing countries, including the Green Climate Fund and other public and private pledges. The Paris Agreement requires a new commitment of at least $100 billion per year to be agreed before 2025.
Although both mitigation and adaptation need increased climate financing, adaptation typically receives less support and less action from the private sector. A report by the OECD found that 16% of global climate finance was directed toward adaptation in 2013–2014, compared to 77% for mitigation. The Paris Agreement calls for a balance between adaptation and mitigation funding, with a focus on increasing support for countries most vulnerable to climate change, such as least developed countries and small island developing states. The agreement also emphasizes the importance of public grants for adaptation, as these measures receive less investment from the public sector.
In 2015, 20 multilateral development banks and members of the International Development Finance Club introduced five principles to guide climate action in their investments: commitment to climate strategies, managing climate risks, promoting climate-smart goals, improving climate performance, and accounting for their own actions. By January 2020, the number of members following these principles had grown to 44.
The increased attention on adaptation financing in Paris led to specific outcomes, such as the G7 countries' announcement to provide $420 million for climate risk insurance and the launch of the Climate Risk and Early Warning Systems (CREWS) Initiative. The largest donors to multilateral climate funds, including the Green Climate Fund, are the United States, the United Kingdom, Japan, Germany, France, and Sweden.
It is not possible to adapt to all effects of climate change, even with the best efforts. Severe damage may still occur. The Paris Agreement recognizes this type of loss and damage, which can come from extreme weather events or slow-onset events like land loss due to rising sea levels for low-lying islands. Previous agreements classified loss and damage as a subset of adaptation.
The push to address loss and damage as
Reception
The agreement was praised by French president François Hollande, UN secretary-general Ban Ki-moon, and Christiana Figueres, Executive Secretary of the UNFCCC. Brazil's president, Dilma Rousseff, called the agreement "fair and lasting," and India's prime minister, Narendra Modi, praised the agreement's focus on fairness. When the agreement received the required signatures in October 2016, US president Barack Obama said, "Even if we reach all our goals, we will still have more work to do." He also stated, "this agreement can help prevent some of the worst effects of climate change and help other countries reduce their emissions over time."
Some environmentalists and analysts responded cautiously, recognizing the "spirit of Paris" in uniting countries, but were less hopeful about how quickly countries would take action and how much help the agreement would give poorer nations. James Hansen, a former NASA scientist and leading climate change expert, criticized the agreement for including mostly "promises" or goals instead of strong commitments and called the Paris talks a fraud with "no action, just promises." Criticism of the agreement from those who oppose climate action has been scattered, which may be due to the agreement's weaknesses. This type of criticism often focuses on national sovereignty and the lack of effectiveness in international efforts.
Precise methodology and status of goal
The Paris Agreement asked countries to try to keep the rise in global temperatures to no more than 1.5°C above levels from before the industrial era. However, it did not explain exactly how to measure this temperature increase. In a 2018 report called "Global Warming of 1.5°C," the IPCC described the method used to calculate this goal:
The temperature increase is measured as the average of global temperatures over a 30-year period, compared to the average temperature from 1850 to 1900. For the most recent 15 years, scientists use a straight-line estimate based on recent data (though the report did not define how many years are considered "recent"). Using this method, the average temperature increase for the 30 years ending in 2017 was about 1.03°C, and scientists predicted the 1.5°C threshold would be reached around 2040.
As of 2024, the same method predicts the 1.5°C level will be reached sometime in 2029. This prediction may be too optimistic, as the warming trend from 2017 to 2024 shows the original estimate for 2017 was about 0.1°C lower than the actual increase.