NCs provide information on greenhouse gas (GHG) inventories, measures to mitigate and to facilitate adequate adaptation to climate change, and any other information that the Party considers relevant to the achievement of the objective of the Convention. NCs are submitted every four years.
BURs provide an update of the information presented in NCs, in particular on national GHG inventories, mitigation actions, constraints and gaps, including support needed and received. The first BUR should be submitted by December 2014, or consistent with the Party's capabilities or level of support, and every two years thereafter as a summary of their NC or a stand-alone report.
The core elements of NCs include relevant information on national circumstances, GHG inventories, a vulnerability and adaptation assessment, mitigation assessment, financial resources and transfer of technology, and education, training and public awareness.
The preparation of NCs is mandated by Article 4, paragraph 1 and Article 12, paragraph 1 according to which each Party shall communicate to the Conference of the Parties, through the secretariat, the following elements of information:
(a) A national inventory of anthropogenic emissions by sources and removals by sinks of all greenhouse gases not controlled by the Montreal Protocol, to the extent its capacities permit, using comparable methodologies to be promoted and agreed upon by the Conference of the Parties.
(b) A general description of steps taken or envisaged by the Party to implement the Convention.
(c) Any other information the Party considers relevant to the achievement of the objective of the Convention and suitable for inclusion in its communication, including, if feasible, material relevant for calculations of global emission trends.
Guidelines for the preparation of initial NCs from non-Annex I Parties were adopted at COP 2 in Geneva in 1996. COP 5 (Bonn, 1999) initiated a process of reviewing the guidelines, with the aim of improving them and established a Consultative Group of Experts on National Communications from non-Annex I Parties
(CGE) in order to improve the process of preparation of NCs by non-Annex I Parties. The CGE made major contributions to the review of the guidelines.
At COP 8 (New Delhi, 2002) Parties adopted the revised guidelines. (decision 17/CP.8).
The core elements of BURs from non-Annex Parties include an update on their national GHG inventories, information on mitigation actions taken and their effects, and an outline of their needs and support received.
COP 17 also decided that that the first BUR submitted by Parties by shall cover, at a minimum, the inventory for the calendar year no more than four years prior to the date of the submission, or more recent years if information is available, and that subsequent BURs shall cover a calendar year that does not precede the submission date by more than four years.
Developing countries, consistent with their capabilities and the level of support provided for reporting, should submit their first BUR by December 2014. The least developed country Parties and small island developing States may submit BURs at their discretion; every two years, either as a summary of parts of their NC in the year in which the NC is submitted or as a stand-alone update report;
The COP 17 adopted the guidelines for the preparation of BURs from non-Annex I Parties contained in annex III of decision 2/CP.17, and also decided the following that these guidelines are to be reviewed and revised as appropriate, in accordance with decisions of the Convention.