United Nations Framework Convention on Climate Change

• 1. Introduction

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  On the 9th of May 1992, in a conference room in New York, negotiators from around the world put the finishing touches on a document that would bind nations together in an unprecedented way. A few weeks later, in Rio de Janeiro, 154 countries signed the United Nations Framework Convention on Climate Change. The goal was stark: prevent dangerous human interference with the climate system. The question that would haunt the decades that followed was whether nations would actually follow through.

  The UNFCCC entered into force on the 21st of March 1994. Since then, it has grown to 198 parties, met annually in major cities from Berlin to Dubai, and spawned some of the most consequential and contentious international agreements ever attempted. Its central tension is one the treaty itself articulates: all countries share responsibility for the problem, but developed nations must take the lead because they caused most of it. What that principle looks like in practice has shaped every negotiation since.

• 2. A Treaty Born in Rio

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  The scientific foundation for the UNFCCC arrived two years before the treaty itself. The IPCC's First Assessment Report, published in 1990, laid out the emerging scientific consensus: greenhouse gases were rising in the atmosphere because of human activity, and the Earth's surface was warming as a result. That report provided the political momentum for governments to act.

  The text of the treaty was hammered out at an Intergovernmental Negotiating Committee session in New York, running from the 30th of April to the 9th of May 1992. The convention was formally adopted on the 9th of May and opened for signature on the 4th of June 1992 at the Earth Summit in Rio de Janeiro, the informal name for the United Nations Conference on Environment and Development. By the 12th of June, 154 nations had signed.

  Article 2, the convention's core, calls for stabilizing greenhouse gas concentrations at a level that would not dangerously disrupt the climate. It also specifies the goals that define success: ecosystems must be able to adapt naturally, food production must not be threatened, and economic development must be able to continue in a sustainable way. Article 3 established the principle of "common but differentiated responsibilities," a phrase that would anchor decades of diplomatic argument. Annex I countries, initially 38 developed nations, were expected to return their emissions to 1990 levels by 2000.

• 3. The Annual Ritual of Negotiation

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  COP1, the first Conference of the Parties, met in Berlin in 1995 and started a tradition that has continued almost every year since. Each COP is the supreme decision-making body of the convention, where governments assess progress and negotiate next steps. The meetings typically run for about twelve days and draw thousands of participants, including thousands of observers from civil society, business, and academia.

  COP3 in Kyoto in 1997 produced the Kyoto Protocol, which created legally binding emission reduction targets for developed countries. COP21 in Paris in 2015 delivered the Paris Agreement, which superseded the Kyoto Protocol and set the current targets: limiting global temperature rise to well below 2 degrees Celsius above pre-industrial levels, and aiming for 1.5 degrees. The Paris Agreement entered into force on the 4th of November 2016.

  COP28 in the United Arab Emirates in 2023 held a milestone: the first global stocktake under the Paris Agreement, a formal review of whether countries are meeting their targets. The UAE nominated Sultan al-Jaber, who simultaneously led Abu Dhabi's national oil company ADNOC, to preside over that meeting. Azerbaijan hosted COP29 in 2024, and Brazil hosted COP30 in 2025.

• 4. Who Owes What to Whom

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  The UNFCCC divides its 198 parties into distinct categories, each carrying different obligations. Annex I parties are the 43 industrialized nations and economies in transition, including the European Union and the former Soviet-bloc states of Eastern Europe and Russia. Within that group, 24 countries listed in Annex II are required to provide financial and technical support to developing countries.

  The 49 least-developed countries hold special status under the treaty because of their limited capacity to adapt to climate change. Non-Annex I parties, which are mostly lower-income developing nations, have lighter formal obligations but can voluntarily upgrade their status as their economies grow.

  Article 4 of the convention addresses the asymmetry directly. It states that developing countries can only implement their commitments to the extent that developed countries actually deliver on their own commitments regarding financial resources and technology transfer. The Durban Platform in 2012 reaffirmed that poverty eradication and social development remain "the first and overriding priorities" for developing country parties, and that their share of global emissions will grow as they address those needs.

  The Green Climate Fund, linked to UN Sustainable Development Goal 13, was designed to operationalize this financial commitment. One of the SDG 13 targets calls for developed countries to jointly mobilize one hundred billion US dollars annually by 2020 from all sources to address developing countries' needs. A single indicator tracks progress: the amounts provided and mobilized each year toward that goal through to 2025.

• 5. Criticism and Fracture

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  National Geographic pointed out before the 2015 Paris conference that in the roughly twenty years since Rio, countries had met twenty times without measurably reducing carbon emissions, adding nearly as much carbon to the atmosphere as in the entire previous century.

  The structural reason is baked into the treaty. With more than 190 countries at the table and all decisions made by consensus, any single party can effectively veto progress. The United States never ratified the Kyoto Protocol, arguing that it did not cover developing countries, which by the time of those debates included the largest emitters. Canada withdrew from the Kyoto Protocol in 2011, citing the financial penalties it would face and the wealth transfers that would result. Japan said in 2010 it would not sign a second Kyoto commitment period because it would face restrictions not shared by its main economic competitors, China, India, and Indonesia.

  At the 2012 conference in Doha, last-minute objections from Russia, Ukraine, Belarus, and Kazakhstan were set aside by governing officials, and those countries indicated they would likely withdraw or decline to ratify. The UK's climate change department alone took more than 3,000 flights over two years at a cost of over one million three hundred thousand pounds sterling, an irony that critics were quick to note.

  The UNFCCC also failed, especially during the Kyoto years, to deliver adequate transfers of environmentally sound technologies to developing countries. The technology mechanism it created distributed resources too slowly, contributing to low ratification numbers for the Kyoto Protocol's second commitment period. The United States announced its intention to withdraw from the UNFCCC treaty itself in January 2026, becoming the only country to do so.

• 6. Beyond the Main Table

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  Action for Climate Empowerment, or ACE, is a term the UNFCCC adopted in 2015 to replace the more bureaucratic label "Article 6." It refers to six priority areas spelled out in the convention's original 1992 text: education, training, public awareness, public participation, public access to information, and international cooperation. The UNFCCC frames the implementation of all six as the pivotal factor in enabling broad participation in solving the climate challenge.

  Civil society has organized itself around the annual COP meetings from the very beginning. Business and industry NGOs and environmental NGOs have been admitted since 1992. Local governments and municipal authorities joined at COP1 in 1995. Indigenous peoples organizations gained formal status at COP7 in 2001, research organizations at COP9 in 2003, and trade unions, women and gender groups, youth NGOs, and farmer organizations followed in subsequent years. By 2014, Peru and France joined with the UN to create the Global Climate Action Portal NAZCA, a platform for recording and checking climate commitments from non-state actors.

  In 2014, the IPCC released its Special Report on Global Warming of 1.5 degrees Celsius after the UNFCCC invited the panel to prepare it. That report found it was technically possible to stay below 1.5 degrees during the 21st century, but only with deep, rapid cuts across all sectors of society. It also concluded that warming of 2 degrees would produce substantially worse impacts than 1.5 degrees. The report had what the source describes as an unprecedented impact in the media and with the public, placing the 1.5-degree target at the center of climate activism. The 2021 Race-to-Zero Emissions Breakthroughs campaign, launched at that year's COP, set a threshold of 20 percent adoption within any sector as the tipping point at which the whole sector begins to irreversibly change.

• 7. The Secretariat and Its Leaders

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  The UNFCCC Secretariat operates from the UN Campus in Bonn, Germany, in offices that were formerly located in Haus Carstanjen and in a campus building known as Langer Eugen. The secretariat is established under Article 8 of the convention and headed by the Executive Secretary, who coordinates the mechanics of the annual negotiations.

  Michael Zammit Cutajar of Malta served as the first Executive Secretary from 1995 to 2002. Joke Waller-Hunter of the Netherlands took the role from the 1st of May 2002 until her death on the 14th of October 2005. Yvo de Boer of the Netherlands succeeded her and served from August 2006 to July 2010. Christiana Figueres of Costa Rica then led the secretariat through the years that produced the Paris Agreement, serving from 2010 to 2016.

  Patricia Espinosa of Mexico, former Secretary of Foreign Affairs and Ambassador to Germany, was appointed Executive Secretary by Secretary-General Ban Ki-moon on the 18th of May 2016 and took office on the 18th of July 2016. She retired on the 16th of July 2022. Ibrahim Thiaw of Mauritania, who also serves as Under Secretary General and head of the UN Convention to Combat Desertification, stepped in as acting Executive Secretary until Secretary-General António Guterres appointed Simon Stiell, a former environment minister from Grenada, to the permanent role on the 15th of August 2022. In 2016, the UNFCCC received the Prince or Princess of Asturias Award for International Cooperation.