The summit results in some of the first international agreements on climate change, which become the foundation for future accords. Among them is the UN Framework Convention on Climate Change (UNFCCC) [PDF], which aims to prevent “dangerous” human interference in the climate system, acknowledges that human activities contribute to climate change, and recognizes climate change as an issue of global concern. The UNFCCC, which went into force in 1994, does not legally bind signatories to reduce greenhouse gas emissions and gives no targets or timetables for doing so. But it requires frequent meetings between the ratifying countries, known as the Conference of the Parties, or COP. As of 2019, it has been ratified by 197 countries, including the United States.

1992

Groundbreaking Rio Earth Summit

UNFCCC signatories gather for the first Conference of the Parties, or COP1, in Berlin. The United States pushes back against legally binding targets and timetables, but it joins other parties in agreeing to negotiations to strengthen commitments on limiting greenhouse gases. The concluding document, known as the Berlin Mandate [PDF], lays the groundwork for what becomes the Kyoto Protocol, but it is criticized by environmental activists as a political solution that does not prompt immediate action.

1995

First Meeting of UNFCCC Signatories

At COP3 in Japan, the conference adopts the Kyoto Protocol [PDF]. The legally binding treaty requires developed countries to reduce emissions by an average of 5 percent below 1990 levels and establishes a system to monitor countries’ progress. But the protocol does not compel developing countries, including high carbon emitters China and India, to take action. It also creates a carbon market for countries to trade emissions units and encourage sustainable development, a system known as “cap and trade.” Countries must now work out the details of implementing and ratifying the protocol.

1997

In Kyoto, First Legally Binding Climate Treaty

2001

In Kyoto, First Legally Binding Climate Treaty

The Kyoto Protocol is in jeopardy after talks collapse in November 2000 and the United States withdraws in March 2001, with Washington saying that the protocol is not in the country’s “economic best interest.” In July 2001, negotiators in Bonn, Germany, reach breakthroughs on green technology, agreements on emissions trading, and compromises on how to account for carbon sinks (natural reservoirs that take in more carbon than they release). In October, countries agree on the rules for meeting targets set by the Kyoto Protocol, paving the way for its entry into force.

2007

Negotiations Begin for Kyoto 2.0

Before COP13 in Bali, Indonesia, the UN Intergovernmental Panel on Climate Change (IPCC) releases a new report with its strongest language yet confirming that global warming is “most likely” caused by human activity. During the conference, discussions begin on a stronger successor to the Kyoto Protocol. But they come to a standstill after the United States objects to a widely backed proposal that calls for all industrialized nations to cut greenhouse gas emissions by specific targets. U.S. officials argue that developing countries must also make commitments. A delegate from Papua New Guinea tells the United States to “get out of the way” if it does not want to lead the international response to climate change. Washington eventually backs down, and the parties adopt the Bali Action Plan, which establishes the goal of drafting a new climate agreement by 2009.

2009

U.S. Joins Bold Statements at UN

Three months ahead of the target date for a new agreement, several world leaders pledge actions during a UN summit on climate change hosted by Secretary-General Ban Ki-moon. Chinese President Hu Jintao announces a plan to cut emissions by a “notable margin” by 2020, marking the first time Beijing commits to reducing its rate of greenhouse gas emissions. Japanese Prime Minister Yukio Hatoyama pledges to reduce emissions by 25 percent. U.S. President Barack Obama, in his first UN address, says the United States is determined to act and lead, but he doesn’t offer any new proposals. Ban expresses hope that leaders will reach a “substantive deal” during the upcoming conference in Copenhagen.

2010

Temperature Target Set in Cancun

There is increased pressure to reach a consensus in Mexico during COP16 after the failure in Copenhagen and NASA’s announcement that 2000–2009 was the warmest decade ever recorded. Countries commit for the first time to keep global temperature increases below 2°C in the Cancun Agreements. Approximately eighty countries, including China, India, and the United States, as well as the European Union, submit emissions reduction targets and actions, and they agree on stronger mechanisms for monitoring progress. But analysts say it’s not enough to stay below the 2° target. The Green Climate Fund, a $100 billion fund to assist developing countries in mitigating and adapting to climate change, is also established. As of 2019, only around $3 billion has been contributed.

2011

New Accord to Apply to All Countries

The conference in Durban, South Africa, nearly collapses after the world’s three biggest polluters—China, India, and the United States—reject an accord proposed by the European Union. But they eventually agree to work toward drafting a new, legally binding agreement in 2015 at the latest. The new agreement will differ from the Kyoto Protocol in that it will apply to both developed and developing countries. With the Kyoto Protocol set to expire in a few months, the parties agree to extend it until 2017.

2012

No Deal in Doha

Negotiators in Doha for COP18 extend the Kyoto Protocol until 2020, but remaining participants account for just 15 percent of global greenhouse gas emissions. By this time, Canada has withdrawn from the treaty, and Japan and Russia say they will not accept new commitments. (The United States never signed on.) Environmental groups criticize countries for not reaching an effective agreement as Typhoon Bopha slams the Philippines, which they say exemplifies a rise in extreme weather caused by climate change. One of the conference’s successes is the Doha Amendment, under which developed countries agree to assist developing countries mitigate and adapt to the effects of climate change. The agreement also sets delegates on the path toward a new treaty.

2015

Landmark Paris Agreement Reached

One hundred ninety-six countries agree to what experts call the most significant global climate agreement in history, known as the Paris Agreement. Unlike past accords, it requires nearly all countries—both developed and developing—to set emissions reduction goals. However, countries can choose their own targets and there are no enforcement mechanisms to ensure they meet them. Under the agreement, countries are supposed to submit targets known as nationally determined contributions. The mission of the Paris Agreement, which enters into force in November 2016, is to keep global temperature rise below 2°C and pursue efforts to keep it below 1.5°C. But analysts urge more action to achieve this goal. In 2017, President Donald J. Trump withdraws the United States from the agreement, saying that it imposes “draconian financial and economic burdens” on the country.