Nationally determined contributions (NDCs) are countries' main vehicle to signal their commitments and plans to meet the Paris climate agreement's mitigation, adaptation and finance goals. Countries' initial NDCs are very diverse, varying in the types of commitments and metrics included, as well as in the sectors and greenhouse gases they cover. Importantly, these initial NDCs also specify a range of time frames: some go up to 2025, others up to 2030, and a few use other time frames, such as including both 2025 and 2030.

At COP24 in Katowice, countries defined a number of common parameters for governments to use in their NDCs. However, the issue of varying time frames remains unresolved. Countries only agreed at COP24 to use common time frames and do so with those NDCs to be implemented beginning in 2031. This left the tricky question of the common time frame's actual duration outstanding. At COP25 in Madrid, negotiators now have an opportunity to resolve this issue.

WRI's new research paper, Setting a Common Time Frame for Nationally Determined Contributions, discusses how the NDC time frame affects other elements of the Paris Agreement and evaluates five different options for specifying the time frame. The paper also considers how countries might align their domestic processes with an international time frame. The paper finally provides suggestions for a potential decision that countries could consider in their negotiations.

A Decision on Common Time Frames Could Affect the Pace of Climate Action

A common NDC time frame will ensure countries implement and report on their commitments over the same time period, facilitating better understanding and assessment of global progress. The length of the NDC's time frame matters. Longer time frames may lock in insufficient ambition over extended periods of time while shorter time frames provide signals to mobilize short-term investments (in response to the Paris Agreement's global stocktake, the latest climate science, technological breakthroughs or socioeconomic changes). As we face a climate emergency, the decision on common time frames should also accelerate the pace and scale of action by encouraging countries to take on board the outcome of the global stocktake taking place every five years.

Furthermore, as highlighted below, NDCs interact with a number of other elements of the Paris Agreement. In particular, the length of the NDC time frame has important relationships with the Agreement's enhanced transparency framework, cooperative implementation (market and non-market), and the global stocktake.

A Decision on Common Time Frames Must be Made in a Coherent Manner

A key component of the Paris Agreement's enhanced transparency framework is the requirement to track countries' progress in implementing their NDCs. As countries report on their progress, the NDC time frame defines when countries are implementing their NDCs and when they aim to achieve their goals. Getting all countries' NDCs on the same time frame will allow countries to report on their progress at the same stage of their NDC implementation.

The Paris Agreement allows countries to cooperate through market and non-market efforts to achieve their NDCs. This cooperative implementation may involve trading or exchanging emission reduction credits or transferring mitigation outcomes from one country to another. The accounting of these exchanges can be complicated when countries use different NDC targets and time frames. Ongoing negotiations on cooperative efforts frequently refer to "periods for NDC implementation," as well as to crediting and trading periods. A decision on common NDC time frames can define and align the periods currently being discussed for implementation, crediting and trading under Article 6.

Parties to the Paris Agreement assess their collective progress toward the Agreement's long-term goals every five years through a global stocktake. Reports from the enhanced transparency framework are core inputs to the global stocktake on countries' abilities and efforts to achieve their NDCs. A common time frame will facilitate comparability of individual efforts and assessment of collective efforts.

What Options are Countries Currently Discussing?

Negotiators are currently discussing a variety of options, many using either a five-year or 10-year time frame as their basis. WRI's paper focuses on five options for common time frames:

  • Five years
  • Five years, with indicative 10 years
  • 10 years
  • 10 years, with an indicative five-year midpoint
  • Party choice of five or 10 years

Our research compares each of the five options against three criteria: enhanced ambition of climate action and support in line with the long-term goals of the Paris Agreement; alignment with and facilitation of implementing other elements of the Paris Agreement; and administrative feasibility, including institutional conditions.

Based upon this assessment, a mandatory five-year time frame with the option for countries to indicate an additional 10-year time frame would be most suitable. A short-term time frame paves the way for more predictable investments, while giving assurance to citizens and the private sector about their country's determination to improve their decision-making processes and policy design. It also aligns with the five-year rhythm of the Paris Agreement (the global stocktake and communication of NDCs both occur on five-year cycles). By also allowing countries to choose whether they wish to indicate a 10-year time frame as well, this option also addresses the need to offer longer-term signals and certainty.

What Could a Decision at COP25 Look Like?

At COP25, countries should have the goal of reaching a decision and finding appropriate language to operationalize whichever option is agreed upon. Adopting a decision at COP25 will allow time for countries to adjust their national processes and align future NDCs with the decision, allow time for countries to share their experiences adapting their national processes, and support other elements of the Paris Agreement like the enhanced transparency framework and the global stocktake.

To operationalize a decision on common time frames, negotiators should consider three related ideas:

  • Requesting all countries to at least communicate five-year time frames;
  • Allowing countries to also indicate optional 10-year time frames; and
  • Inviting countries to respond to the urgency of climate change by updating their immediate and current NDCs based on the outcome of each global stocktake.



Countries left Katowice with two unresolved issues: the rules for carbon markets under Article 6 and common time frames. Governments should not miss the opportunity in Madrid to demonstrate their resolve to move forward in an effective, coherent and ambitious manner. Making the right decision on common time frames would signal their desire to accelerate the pace of climate action, which is so desperately needed.