Kyoto Protocol

The Kyoto Protocal became legally binding for the 128 participating entities on 16 February 2005.

The Kyoto Protocol broke new ground by defining three innovative “flexibility mechanisms” to lower the overall costs of achieving its emissions targets. These mechanisms enable Parties to access cost-effective opportunities to reduce emissions, or to remove carbon from the atmosphere, in other countries. While the cost of limiting emissions varies considerably from region to region, the effect for the atmosphere of limiting emissions is the same, irrespective of where the action is taken.

Much of the negotiations on the mechanisms has been concerned with ensuring their integrity. There was concern that the mechanisms do not confer a “right to emit” on Annex I Parties or lead to exchanges of fictitious credits which would undermine the Protocol’s environmental goals. The negotiators of the Protocol and the Marrakesh Accords therefore sought to design a system that fulfilled the cost-effectiveness promise of the mechanisms, while addressing concerns about environmental integrity and equity.

All three mechanisms under the Kyoto Protocol are based on the Protocol’s system for the accounting of targets. Under this system, the amount to which an Annex I Party must reduce its emissions over the five year commitment period (known as its “assigned amount”) is divided into units each equal to one tonne of carbon dioxide equivalent. These assigned amount units (AAUs), and other units defined by the Protocol, contribute the basis for the Kyoto mechanisms by providing for a Party to gain credit from action taken in other Parties that may be counted towards it own emissions target.

The three Kyoto mechanisms are:

  • Joint implementation (JI) under Article 6 provides for Annex I Parties to implement projects that reduce emissions, or remove carbon from the atmosphere, in other Annex I Parties, in return for emission reduction units (ERUs). An Article 6 Supervisory Committee is to be established by COP/MOP 1 and this is expected to supervise JI in relation to many JI projects.
  • The clean development mechanism (CDM) defined in Article 12 provides for Annex I Parties to implement projects that reduce emissions in non-Annex I Parties, or absorb carbon through afforestation or reforestation activities, in return for certified emission reductions (CERs, tCERs and lCERs) and assist the host Parties in achieving sustainable development and contributing to the ultimate objective of the Convention. The CDM is supervised by the CDM Executive Board.
  • Emissions trading, as set out in Article 17, provides for Annex I Parties to acquire units from other Annex I Parties. These units may be in the form of AAUs, removal units (RMUs), ERUs, CERs, tCERs and lCERs.

The AAUs, RMUs, ERUs, CERs, tCERs and lCERs are the accounting units of the “assigned amount” of each Annex I Party referred to in the provisions of Article 3 of the Protocol. Each unit is equal to one metric tonne of emissions (in CO2-equivalent terms). AAUs are issued on the basis of the assigned amount pursuant to Article 3.7 and 3.8 while RMUs are issued on the basis of land use, land-use change and forestry (LULUCF) activities (often referred to as “sinks”) under Articles 3.3 and 3.4. In accordance with Article 3.10 and 3.11, the issuance of ERUs results in the cancellation of either AAUs or RMUs, in order that no overall impact on a Party’s assigned amount is felt. Finally, CERs are the additions to assigned amount referred to in Article 3.12. More information may be found on the assigned amount accounting page.

At COP 7 (Marrakesh, October/November 2001), as part of the Marrakesh Accords, Parties completed a package of decisions on the mechanisms and recommended it to COP/MOP 1 for adoption. These decisions are largely based on agreement reached on many difficult political issues at COP 6 part II (Bonn, July 2001) in the form of the Bonn Agreements on the Implementation of the Buenos Aires Plan of Action.

Since COP 7, further decisions have been taken in relation to the Kyoto mechanisms and much work has been undertaken to implement them, in particular regarding the CDM and emissions trading. For further information, see the web pages on the individual mechanisms and on registry systems.

Metric conversion


0cubic meters