Climate change is a global challenge and requires a global solution. Greenhouse gas emissions have the same impact on the atmosphere whether they originate in Washington, London or Beijing. Consequently, action by one country to reduce emissions will do little to slow global warming unless other countries act as well. Ultimately, an effective strategy will require commitments and action by all the major emitting countries.
United Nations Framework Convention on Climate Change
The international response to climate change was launched in 1992, at the Earth Summit in Rio de Janeiro, with the signing of the United Nations Framework Convention on Climate Change  (UNFCCC). The Convention established a long-term objective of stabilizing greenhouse gas concentrations in the atmosphere "at a level that would prevent dangerous anthropogenic interference with the climate system". It also set a voluntary goal of reducing emissions from developed countries to 1990 levels by 2000 - a goal that most countries did not meet. Currently 191 parties, including the US, have ratified the UNFCCC.
UNFCCC First Ten Years:  A Report of the UN Secretariat
Recognizing that stronger action was needed, countries negotiated the 1997 Kyoto Protocol , which sets binding targets to reduce emissions 5.2 percent below 1990 levels by 2012. The Protocol entered into force on February 16, 2005, which made the Protocol's emissions targets binding legal commitments for those industrialized countries that ratified it (the United States has not ratified it). In addition, the market-based mechanisms established under the Protocol, including international emissions trading and the Clean Development Mechanism, became fully operational with the Protocol's entry into force.
Conference of the Parties (COPs)
COP 20 - Lima, Peru 
December 1 - 12, 2014
COP 19 - Warsaw Poland 
November 11 - 23, 2013
COP 18 - Doha, Qatar 
November 26 - December 7, 2012
COP 17 - Durban, South Africa 
November 28 - December 9, 2011
COP 16 - Cancún, Mexico 
November 29 - December 10, 2010
The Cancún Agreements import the essential elements of the Copenhagen Accord into the UNFCCC, including mitigation pledges and operational elements such as a new Green Climate Fund for developing countries and a system of “international consultations and analysis” to help verify countries’ actions. Agreement hinged on finding a way to finesse the more difficult questions of if, when, and in what form countries will take binding commitments. The final outcome leaves all options on the table and sets no clear path toward a binding agreement.
COP 15 - Copenhagen, Denmark 
December 7-18, 2009
A new political accord struck by world leaders at the U.N. Climate Change Conference in Copenhagen provides for explicit emission pledges by all the major economies – including, for the first time, China and other major developing countries – but charts no clear path toward a treaty with binding commitments.
COP 14 - Poznan, Poland 
December 1-12, 2008
Governments resolved in Poznan to shift into “full negotiating mode” in hopes of delivering a comprehensive new climate change agreement in December 2009 in Copenhagen.
COP 13 - Bali, Indonesia 
December 3-15, 2007
In tense and chaotic talks that ran a full day longer than planned, delegates to the UN Climate Change Conference in Bali remained far apart on fundamental issues but in the end agreed to launch a loosely framed negotiating process with the ambitious goal of achieving a new global climate agreement in 2009.
COP 12 - COP/MOP 2 
November 6-17, 2006
Government negotiators at the United Nations Climate Change Conference in Nairobi continued two processes launched last year in Montreal to consider next steps in the international climate effort, and agreed in the final hours to open another track to review the Kyoto Protocol.
COP 11 - Montreal, Canada 
November 28 - December 10, 2005
In two weeks of talks, delegates to the UN Climate Change Conference in Montreal concluded the decade-long round of negotiations that launched the Kyoto Protocol and opened a new round of talks to begin considering the future of the international climate effort.
COP 10 - Buenos Aires 
December 6-17, 2004
COP 9 - Milan, Italy 
December 1-12, 2003
COP 8 - New Delhi, India 
October 23 - Novomber 1, 2002
COP 7 - Marrakech, Morocco 
October 29 - November 9, 2001
COP 6 BIS - Bonn, Germany 
July 16-27, 2001
COP 6 - The Hague, The Netherlands 
November 13 - 24, 2000