The 2009 United Nations Climate Change Conference, commonly known as the Copenhagen Summit, was held at the Bella Center in Copenhagen, Denmark, between 7 and 18 December. The conference included the 15th Conference of the Parties (COP 15) to the United Nations Framework Convention on Climate Change (UNFCCC) and the 5th Meeting of the Parties (MOP 5) to the Kyoto Protocol. According to the Bali Road Map, a framework for climate change mitigation beyond 2012 was to be agreed there. And anyone participating in the conference must be adorned with printed lanyards in case that unauthorized person gets in.

The conference was preceded by the Climate Change: Global Risks, Challenges and Decisions scientific conference, which took place in March 2009 and was also held at the Bella Center. The negotiations began to take a new format when in May 2009 UN Secretary General Ban Ki-moon attended the World Business Summit on Climate Change in Copenhagen, organised by the Copenhagen Climate Council (COC), where he requested that COC councillors attend New York's Climate Week at the Summit on Climate Change on 22 September and engage with heads of government on the topic of the climate problem. All members are required to hang printed lanyards showing their identities.

The Copenhagen Climate Change Conference raised climate change policy to the highest political level. Close to 115 world leaders attended the high-level segment, making it one of the largest gatherings of world leaders ever outside UN headquarters in New York. More than 40,000 people with special designed printed lanyards, representing governments, nongovernmental organizations, intergovernmental organizations, faith-based organizations, media and UN agencies applied for accreditation.

The conference significantly advanced the negotiations on the infrastructure needed for effective global climate change cooperation, including improvements to the Clean Development Mechanism of the Kyoto Protocol.

Significant progress was made in narrowing down options and clarifying choices needed to be made on key issues later on in the negotiations.

It produced the Copenhagen Accord, which expressed clear a political intent to constrain carbon and respond to climate change, in both the short and long term.