The Convention requires all Parties, taking into account their responsibilities and capabilities, to formulate and implement programmes containing measures to mitigate climate change. Mitigation actions could be economy-wide, cover several or single sectors, such as energy supply and demand, transport, buildings, industry, agriculture, forestry and waste management. There is a number of mitigation options, which Parties may use taken into count their national circumstances, availability of technology and financial resources, mitigation potential and the policy implementation issues. There is also a link between climate change mitigation, adaptation and sustainable development.

Mitigation policies and measures used by developed country Parties mostly focussed on the large emitting sectors, such as energy and transport. Strengthening of climate change policy portfolios resulted in policies and measures in some key areas being substantially strengthened, through more stringent requirements, wider coverage and increased investment. Regulatory and fiscal instruments were complimented by market based instruments such as GHG emission trading schemes. Developed countries periodically present their mitigation actions in their National Communications, which are summarised in the compilation and synthesis reports. More recently, developed countries have agreed to implement under the Convention quantified economy-wide emission targets for 2020.

The Kyoto Protocol "operationalizes" the Convention by committing industrialized countries to limit greenhouse gas emissions. Overall, emission limitation or reduction targets add up to, at minimum, five per cent emissions reduction compared to 1990 levels over the five-year period 2008 to 2012. Negotiations are currently on-going to decide on a second commitment period of the Protocol.

Nationally Appropriate Mitigation Actions: developing country Parties have been contributing to global mitigation efforts in several ways. The clean development mechanism (CDM) has been an important avenue of action for these countries to implement project activities that reduce emissions and enhance sinks. More recently, developing countries have agreed to implement Nationally Appropriate Mitigation actions, or NAMAs, with support from developed countries.

Reducing emissions from deforestation and forest degradation: The IPCC (2007) estimated emissions from deforestation in the 1990s to be at 5.8 GtCO2/year. Parties to the UNFCCC process recognized the contribution of greenhouse gas emissions from deforestation in developing countries to climate change and the need to take action to reduce such emissions. Developing countries are encouraged to contribute to mitigation actions in the forest sector by undertaking activities relating to reducing emissions from deforestation and forest degradation, conservation of forest carbon stocks, sustainable management of forests and enhancement of forest carbon stocks (REDD-plus). In the REDD Web platform relevant organizations and stakeholders are encouraged to submit information relating to REDD-plus.

Emissions from international aviation and maritime transport contribute increasingly to global GHG emissions. To address these emissions cooperation among the UNFCCC and the International Civil Aviation Organization and the International Maritime Organization is important.

Response measures: All over the world, many measures are being taken in order to mitigate climate change by countries trying to live up to their commitments under the Convention and Kyoto Protocol. According to the Convention, Parties shall take into consideration the specific needs and concerns of developing country parties arising from the impact of response measures. The Kyoto Protocol commits Parties to strive to minimize adverse economic, social and environmental impacts on other Parties, especially developing country Parties.