The United Nations Climate Change Conference is taking place in Cancun, Mexico, from 29 November to 10 December 2010. It encompasses the sixteenth Conference of the Parties (COP) and the sixth Conference of the Parties serving as the Meeting of the Parties to the Kyoto Protocol (CMP), as well as the thirty-third sessions of both the Subsidiary Body for Implementation (SBI) and the Subsidiary Body for Scientific and Technological Advice (SBSTA), and the fifteenth session of the AWG-KP and thirteenth session of the AWG-LCA

.

Over a decade ago, most countries joined an international treaty — the United Nations Framework Convention on Climate Change (UNFCCC) — to begin to consider what can be done to reduce global warming and to cope with whatever temperature increases are inevitable. More recently, a number of nations approved an addition to the treaty: the Kyoto Protocol, which has more powerful (and legally binding) measures. The UNFCCC secretariat supports all institutions involved in the climate change process, particularly the COP, the subsidiary bodies and their Bureau.

The Kyoto Protocol, an international and legally binding agreement to reduce greenhouse gas emissions worldwide, entered into force on 16 February 2005.

The negotiating process on climate change revolves around the sessions of the Conference of the Parties to the UNFCCC (COP), which meets every year to review the implementation of the Convention. The COP adopts decisions and resolutions, published in reports of the COP.  Successive decisions taken by the COP make up a detailed set of rules for practical and effective implementation of the Convention.

The COP serves as the meeting of the Parties to the Kyoto Protocol (CMP), which also adopts decisions and resolutions on the implementation of its provision. 

Thousands of participants including government representatives and observer organizations have attended previous climate change conferences.  The sessions in Bali attracted over 10,000 participants, including some 3,500 government officials, over 5,800 representatives of UN bodies and agencies, intergovernmental and non-governmental organizations, and nearly 1,500 accredited members of the media.  The UN Climate Change Conference in Poznań last year came close to that size, with close to 9,300 participants.

Expressions of interest or invitations to host a climate change conference come from the governments of a prospective host country and are decided by the Conference of the Parties.

Following the procedural rules of the Conference, the office of President normally rotates among the five UN regional groups and in 2009 the Conference will be hosted by the Western European and Others Group (WEOG).  The last time WEOG held the Presidency of the Conference was in 2005 (COP 11/CMP 1).

At COP 13/CMP 3 in Bali, Indonesia, the government of Denmark extended an invitation to host COP 15/CMP 5.  When the sessions are held at the invitation of a host country, it is customary for the COP and CMP to elect as President a Minister from that country.

Following technical missions to assess the facilities at the venue envisaged by the host country, the Government and the UNFCCC concluded a Host Country Agreement indicating all the facilities and equipment needed.

Participation in COP 15 and CMP 5 is restricted to duly nominated representatives of Parties, observer States, accredited observer organizations and accredited press/media.  Those Parties to the Convention that are not Parties to the Protocol may participate as observers in the meeting of the Parties. 

All Conferences to date have had a high-level segment attended by anywhere from 70 to 100 ministers and senior officials, usually at the end of the session.  The high-level segment normally includes an opening or welcoming event with some head of state participation and is partly attended by the Secretary-General of the United Nations.