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22.08.2022 · Lauri Peterson and Harro van Asselt

Assessing the enhancement of Nationally Determined Contributions: Why and how?


The five-yearly climate action plans in the form of Nationally Determined Contributions (NDCs) are a core feature of the climate governance architecture of the Paris Agreement. Parties to the treaty need to ensure that each successive NDC submission is more ambitious than the previous to meet the Agreement’s temperature goals.

It is vital to keep track of the commitments made in successive NDCs for two main reasons. First, the continued monitoring of countries’ efforts allows us to hold governments to account for their promises and keep an eye on changes in their policy ambition. Second, studying NDC enhancement can shed light on why some countries are able to enhance their NDC commitments while others lag behind.

But how does one actually going about assessing whether NDCs have been enhanced?

The challenges of assessing NDC enhancement

Measuring NDC enhancement is difficult as NDCs come in various formats and contain vastly different levels of information. While some span dozens of pages of details, others lay out their plans in a couple of pages.

NDCs incorporate various types of mitigation targets, which can be based on an absolute or a relative level of greenhouse gas (GHG) emissions. The most common mitigation target in updated NDCs were defined as a GHG mitigation target relative to a baseline scenario or a base year. For example, in 2021 Armenia submitted an updated 2030 mitigation target that promised to reduce emissions by 40% relative to 1990. Other countries suggest a maximum level of emissions. Chile’s updated NDC, for instance, proposes that it will not emit more than 1100 MtCO2 equivalent emissions between 2020 and 2030. Yet other countries have proposed purely sectoral targets or non-GHG targets. For example, in 2020 Papua New Guinea submitted a target to reduce emissions in the forestry sector by 10 MtCO2eq compared to 2015 by 2030.

In addition to the variety of targets, it is unclear whether we should pay greater attention to more imminent (e.g. 2025 or 2030) targets, or to carbon-neutrality targets proposed for later years, such as for 2050 or 2060. Net-zero targets for later years may sound immensely ambitious, but they require less effort on the side of the government – especially in democratic countries, where election cycles normally last four to five years. Governments may propose long-term targets strategically, knowing that they will no longer be in charge by then. To prove this point, for instance, 13 of the updated NDCs that included a net-zero target did not enhance the more immediate 2030 emission target (e.g., Australia, Bhutan and Switzerland).

There are also other issues. For instance, should the addition of new policies to the NDC constitute strengthened ambition? Many countries submitted NDC updates with non-GHG targets and emphasized policy actions instead. Does the inclusion of new sectors, policies and measures also represent enhancement? If not, where should one draw the line? These are just some of the challenges that researchers need to confront when developing their own methodology for assessing whether NDCs have been enhanced.

A method for assessing enhanced NDCs

In our study, we look at countries that submitted updated or revised NDCs (with the EU analysed as a single unit since the commitments of its Member States are represented by a single EU-wide NDC). To identify whether NDCs have been enhanced, we have drawn on data provided by the Climate Watch platform. The indicator is based on the proposed reduction of total GHG emissions by 2030 in the updated or revised NDC. We coded the NDCs as either “enhanced GHG emission target” or “no enhancement”. The dataset includes countries that submitted their first and revised or updated NDC during the period between March 2016 and December 2021.

The use of 2030 GHG emissions as an indicator of enhancement is favourable for three reasons. First, this measure accounts for dynamic target enhancement in relation to the original pledge, rather than static aggregate climate commitments. This allows us to investigate the reasons for a change in commitments instead of the factors that set the overall level of climate action per country.

Second, the indicator accounts for total emission reductions by 2030, which represents a more generalisable and stricter interpretation of NDC enhancement. As previously mentioned, countries maintain considerable discretion over the revision of their NDCs. While some of these updated commitments, such as pledging to limit total emissions by a set year, may be highly stringent, others, such as adding an ineffective policy measure, can be relatively undemanding. It is difficult to compare such changes with the rest of the sample. We find that mitigation commitments, as translated into 2030 GHG emission reductions, are a reasonably rigorous measure, since they require a quick response, and disregard attempts to change baselines (i.e., inflate the updated business-as-usual scenario) in favour of the proposer. Sixty updated NDCs out of 122 made some type of changes to the business-as-usual or base year calculations.

Finally, the 2030 GHG emission target improvement allows for better comparison and covers more countries than similar databases, such as Climate Action Tracker (CAT). For instance, our dataset accounts for 122 countries, while CAT analysed only 35 countries for the 2015–2021 period. It’s useful to get a comprehensive and comparative global overview of climate targets.

Using this indicator, we find that more than half (52%) of the 122 updated or revised NDCs proposed before December 31, 2021, enhanced their 2030 emissions pledge. This method of measuring NDC enhancement can not only provide a fruitful basis for analysing the extent of global climate commitments, but can also allow us to start exploring factors that underpin NDC enhancement. This opens up brand new avenues for all kinds of research necessary to assess and inform the ratcheting mechanism of the Paris Agreement.

For more details about our study, see Deliverable D4.1.

Lauri Peterson is a postdoctoral researcher at the University of Eastern Finland (profile page)

Harro van Asselt is a professor of climate law and policy at the University of Eastern Finland (profile page)