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Climate Change Mitigation


Climate change mitigation means efforts to reduce greenhouse gas (GHG) emissions in the atmosphere and enhancing carbon sinks. Carbon sinks are natural or artificial reservoirs that absorb more carbon dioxide (CO2) from the atmosphere than they emit, such as forests and oceans.


Climate change mitigation strategies range from transitioning to renewable energy systems to energy efficiency measures and the creation of carbon sinks through reforestation.



The Intergovernmental Panel on Climate Change (IPPC)’s special report on the impacts of global warming of 1.5 °C,  highlights: “All paths towards limiting global warming to 1.5°C are dependent on the reduction of GHG emissions globally to net 0 by 2050.” (Rogelj et al., 2018).


Climate change mitigation is a central component of global climate action. By signing the Convention, Parties committed to implement measures to mitigate climate change impacts, which range from national policies, incentives schemes and investment programmes across all sectors, aimed at limiting GHG emissions in the atmosphere as well as enhancing carbon sinks.

The Kyoto Protocol was adopted in 1997, operationalized the Convention and set binding targets for the reduction of GHG emissions in industrialized countries, as included in Annex I of the Convention. The initial commitment period was 2008-2012. It further established the differentiation between developed and developing countries. Developed countries have subsequently set caps for GHG emissions which encompass all sectors of the economy, whilst developing countries efforts centred on the implementation of programmes and projects.


After COP15 and COP16 in 2009 and 2010, developing countries implemented nationally appropriate mitigation actions (NAMAs). With the Doha amendment, the Kyoto Protocol’s second commitment period was set from 2013-2020.

Image by Su San Lee



It is a flexibility mechanism and the first global environmental investment/credit scheme, detailed in the Kyoto Protocol (Article 12). The CDM enables developed countries and companies to carry out project activities in developing countries intended to reduce emissions and enhance carbon sinks. These projects generate certified emissions reductions (CER) units which can be traded. Its overarching goal is to promote sustainable development. The mechanism has been highly contested due to its structural issues and the failure to generate new investment for renewables. Some CDM projects have also been connected to human rights scandals. See for instance CIEL's statement on the hydroelectric dam Barro Blanco and it's consequences for indigenous peoples in the region. Human rights and gender activists have therefore been advocating for human rights safeguards and participation to be central for the implementation of market-based mechanisms (see more under Topic: Article 6). 

Before COP 21 in 2015 in Paris, all Parties prepared intended nationally determined contributions (INDCs) which outlined national efforts to reduce GHG emissions and increase resilience. However, these featured a diversity of efforts and several problematic issues such as absolute vs. relative quantified national targets and sectoral targets. Therefore, as there was no harmonized framework of guidelines and metrics to use when elaborating the INDCs, they were all very different in scope and hard to compare.

To implement the Paris Agreement and its goal of limiting global warming well below 2°C (preferably to 1.5°C) , compared toabove pre-industrial levels, mitigation has a prominent place in Article 4. With the ratification of the Agreement INDCs were formalized through the planning document called nationally determined contributions (NDCs), which outlines an inventory of countries' GHG emissions and indicates the strategies they intend to put in place to reduce their emissions. Before 2020, countries have to submit “enhanced NDCs”, which should showcase the Parties' highest possible ambition.


The notion of differentiation emphasises that developed and developing countries have different responsibilities as well as capabilities when it comes to the pursuit of sustainable development and the reduction of GHG emissions. This is reflected by more specific guidelines and binding targets for developed countries in the Kyoto Protocol, whilst developing countries should be granted more flexibility. It relates to the principle of common but differentiated responsibilities and respective capabilities (CBDRRC), introduced in the United Nations Framework Convention on Climate Change of Earth Summit in Rio de Janeiro, 1992. The Paris Agreement is: 

“guided by its principles, including the principle of equity and common but differentiated responsibilities and respective capabilities, in the light of different national circumstances” (Paris Agreement, 2015). 

Article 4, Paragraph 4 of the Paris Agreement holds that developing countries are “encouraged to move over time towards economy-wide emission reduction or limitation targets in the light of different national circumstances.” The principle thus acknowledges differing financial and technological means that might be lacking in developing countries and also different economic realities, to prepare NDCs at the same level as developed countries. CBDRRC is also closely connected to the principle of climate justice and aimed at enabling a climate regime based on equity and fair effort sharing. Developing countries and least developed countries have historically contributed less to global warming than developed countries and should therefore be held to a different standard. However, critics of the CBDRRC principle say it limits ambitious climate action, which is seen as the goal and strength of the Paris Agreement.


At COP24 and COP25, Parties specified common features of national contributions, both in terms of content, form and duration. These characteristics had to be precise enough to ensure the Paris Agreement regime remained ambitious while also respecting the differing capacities and responsibilities of countries. Discussions focussed on:


Accounting for Parties’ NDCs

The COP decided in its draft decision that: “in accounting for anthropogenic emissions and removals corresponding to their nationally determined contributions under Article 4, paragraph 13, of the Paris Agreement, Parties shall account for their nationally determined contributions in accordance with the guidance contained in annex II”. The draft decision further outlines features of the NDCs, information to facilitate clarity, transparency and understanding (CTU).


Common Time Frames for NDCs

A decision on the common frequency by which Parties update or communicate their NDCs, could not be reached at COP24 in 2018, SB50 [1] [2] [3] and COP25 in 2019. Currently, those parties with a 5-year NDC are requested to communicate by 2020 a new NDC and those parties with a 10-year NDC are requested update their NDC by 2020. This issue is to be resolved by 2023 when the first global stocktake is due to take place.


The NDC Registry

NDCs are recorded in an online registry, as referred to in Article 4 Paragraph 12 of the Paris Agreement , which is publicly available and handled by the UNFCCC secretariat. Modalities and procedures for the operation and use of this public registry were subject of the negotiations at COP24 and informal consultations continued until COP25 in 2019. Also at the 25th COP, this topic could not be finalized. Until the modalities and procedures of the public NDC registry are finalized, communicated NDCs are registered and available in the interim NDC registry.

The following scenarios are looked into:

  • a 5 year NDC scenario

  • a 10-year NDC scenario

  • and a 5+5 scenario: a 5 year NDC and an indicative 10-year action plan.

A decision on this matter is politically charged[1] . Parties and civil society drew direct links between ambition and common time frames, since agreeing on timeframes which match the Paris ambition cycle of 5 years would support ambitious climate action and urgency, whilst a 10-year scenario could potentially lock in low ambition levels and slow down climate action.


Article 6 and Overall Mitigation

At COP25, discussions focussed on Article 6 and the challenge to secure an overall mitigation in global emissions (OMGE), which refers to maintaining an overall reduction in emissions in the atmosphere, as opposed to offsetting emissions in one country in another one. You can find out more on this topic in the Issues section on Article 6.


Carbon Brief. 2019. COP25: Key Outcomes Agreed At The UN Climate Talks In Madrid | Carbon Brief. [online] Available at: <> [Accessed 29 December 2020]. (2020). MITIGATION | Meaning In The Cambridge English Dictionary. [online] Available at: <> [Accessed 2 October 2020].

EEA (2020). EEA Glossary: Carbon Sink. [online] Available at: <> [Accessed 6 October 2020]. 2020. ENB Report | COP24 | 4 November 2018 |Katowice, Poland | IISD Reporting Services. [online] Available at: <> [Accessed 6 October 2020].


Image by L.W.

For More Information

Mitigation Pathways Compatible with 1.5°C in the Context of Sustainable Development 2020. ENB Report | COP 25 | 2-15 December 2019 | Madrid, Spain | IISD Reporting Services. [online] Available at: <> [Accessed 6 October 2020].

Rogelj, J., D. Shindell, K. Jiang, S. Fifita, P. Forster, V. Ginzburg, C. Handa, H. Kheshgi, S. Kobayashi, E. Kriegler, L. Mundaca, R. Séférian, and M.V.Vilariño, 2018: Mitigation Pathways Compatible with 1.5°C in the Context of Sustainable Development. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. In Press.

Paris Agreement (Dec. 13, 2015), in UNFCCC, COP Report No. 21, Addendum, at 21, U.N. Doc. FCCC/CP/2015/10/Add, 1 (Jan. 29, 2016) [hereinafter Paris Agreement]. (2020). Introduction to Mitigation [online] Available at: <> [Accessed 2 June 2020]. 2020. Mitigation in the negotiations [online] Available at: <> [Accessed 6 October 2020].

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