Climate mitigation is largely a regional competence, negotiated at federal level.

In 2002, a cooperation agreement between the Federal State, the Flemish Region, the Walloon Region and the Brussels-Capital Region creates the National Climate Commission, in order to comply with the UNFCCC and the Kyoto Protocol, which stipulate that all countries must have a national climate plan, implement it and report their net greenhouse gas emissions.

The Cooperation Agreement was created by:

The Federal State, represented by the Minister responsible for Mobility and Transport, the Minister responsible for the Environment and the State Secretary responsible for Energy;

The Flemish Region, represented by the Flemish Government, in the person of its Minister-President, the Flemish Minister responsible for the Environment and the Flemish Minister responsible for Energy;

The Walloon Region, represented by the Walloon Government, in the person of its Minister-President, the Walloon Minister for the Environment and the Walloon Minister for Energy;

The Brussels-Capital Region, represented by the Government of the Brussels-Capital Region, in the person of its Minister-President, the Brussels Minister for the Environment, the Brussels Minister for Energy and the Brussels Secretary of State for Energy.

The National Climate Commission is responsible for climate management in Belgium. Its 2 main responsibilities are:

Reporting to the UNFCC and the EU on Belgium's greenhouse gas emissions (Greenhouse Gas Inventories). To this end, the National Climate Commission collects greenhouse gas data from each region (and additional data from the federal government) and combines them to produce the national reports.

Supporting the different governments (federal and regional) in drawing up the National Climate Plan, together with the Expanded Interministerial Conference. The Plan is then approved by the different governments, each according to their competences.

The secretariat of the National Climate Commission is provided by the "Celllule Interrégionale de l'Environnement" (IRCEL-CELINE). This also means that IRCEL-CELINE is the body that collects the greenhouse gas inventories of the regions and compiles them into a Belgian inventory that is reported to the UNFCCC and the EU. (Art. 21 of the Cooperation Agreement).

The Belgian regions do not currently have a harmonised accounting system for measuring and recording greenhouse gas emissions. The National Climate Commission also has the mandate to try to harmonise these methodologies where possible (Ch. II, Art. 9), something that has not been done so far (see 2019 Coalition Agreements).