The conference was an historic event. The Parties to the United Nations Framework Convention on Climate Change (UNFCCC) met for the 11th time, while marking the entry into force of the Kyoto Protocol. At Montreal, the first ever Conference of the Parties serving as the Meeting of the Parties to the Protocol (CMP) ran parallel to the Conference of the Parties to the Convention (COP). The United Nations Climate Change Conference was the largest intergovernmental climate conference since the Kyoto Protocol was adopted in 1997. Some 10,000 participants attended.

The conference attracted unprecedented business interest as a result of two operation trading systems: the pan-European emissions trading scheme and the Clean Development Mechanism, a tool to promote sustainable development and combat climate change.