Common Time Frames: Reducing the Number of Options for Glasgow


Aim and Background

This blog post aims to suggest a way in which whittle down the multitude of proposals concerning a Common Time Frame (CTF) for the Paris Agreement to a more manageable number without losing the key features of the originals.

For this, the post considers the different ways in which the existing proposals have been described and proposes a conceptual scheme not only to make them comparable, but synthesise them into smaller number of ‘synthesis options’ – preferably with all the advantages but none of the disadvantages of the originals. Indeed, the post aims to demonstrate that the Glasgow Ambition Cycle is a synthesis option that captures all the proposal in that manner.

But before turning to accomplish this, a few words on the historical background of this issue.

At COP 21 in Paris (2015), it was agreed that the Conference of the Parties serving as the Meeting of the Parties to the Paris Agreement (CMA) “shall consider common time frames for nationally determined contributions at its first session”[Art. 4.10]. In Marrakech, the year after, the CMA agreed to refer the matter to the Subsidiary Body for Implementation (SBI) which, in 2017 in Bonn (SBI 47), “invited Parties and observers to submit, by 31 March 2018, their views on common time frames for NDCs … including on, but not limited to, the usefulness of and options for common time frames and the advantages and disadvantages of those options, for consideration at SBI 48 (April–May 2018)”[SBI 47 conclusions].

By May 2018, 15 Parties had made submissions, which were analyzed in an OCP/ecbi Discussion Note (see below), but the SBI deliberations didn’t progress beyond List of Bullet points by the co-facilitators (SBI.48.2, September 2019). 

The first, and hitherto only decision on the matter was taken at CMA.1 in Katowice when it was decided “that Parties shall apply common time frames to their nationally determined contributions to be implemented from 2031 onward”(Decision 6/CMA.1).  

SBI.50 (June 2019) resulted in an informal note listing 6 options, which was picked up and expanded to 10 options at SBI.51 in Madrid (December 2019), where however the deliberations were rolled over under Rule 16 and have not been taken up since due to the COVID pandemic. What did take place since then was a Technical Dialogue in November 2020, and an Informal Consultation of heads of delegations by the COP Presidencies in April 2021, all of which pointing to a desire by Parties to settle this issue at COP 26 in Glasgow, and consequently, to reduce the number of options that are currently under consideration.

This paper will focus on the 6 options contained in the SBI.50 Options Note. The full set the SBI.51 will be discussed in a forthcoming Technical Paper produced by OCP as strategic partner of AOSIS.

What Timeframes?

One of the key obstacles to progress in the CTF negotiations has been that Parties do not have a common understanding on what ‘timeframe’ actually refers to, let alone what it is to have a ‘common timeframe’.

In June 2018, OCP published an in-depth analysis of this situation on the basis of the Party submissions requested at SBI.47 (Müller 2018.a). It showed that Parties were essentially using two types of interpretations of ‘timeframe’: a material- and a procedural one. The material interpretation is about time intervals associated with the NDCs – to be precise, about target- and implementation periods, and mostly involves references to their lengths. The procedural interpretation is about timetables for the processes of communicating and updating NDCs. 

Subsequent work based on this analysis (listed below in Selected Publications) did suggest a way to “synthesise” CTF proposals, such as the ones contained in the SBI.50 Options Note, by describing their specific action content, that is to say the concrete instructions they contain with regards to who does what, when and with respect to which NDC (as identified by its endpoint).

The paradigm formulation of this type of specific action content is given in paragraphs 23 and 24 of Decision 1/CP.21, and the same language is used in formulating the Glasgow Ambition Cycle proposal to be discussed in the next section as synthesising these two paragraphs into a single common time frame proposal in a way which preserves the advantages of both while avoiding the disadvantages of either:

Decision 1/CP.21 (Adoption of the Paris Agreement):

23. Requests those Parties whose intended nationally determined contribution pursuant to decision 1/CP.20 contains a time frame up to 2025 to communicate by 2020 a new nationally determined contribution and to do so every five years thereafter pursuant to Article 4, paragraph 9, of the Agreement

24. Also requests those Parties whose intended nationally determined contribution pursuant to decision 1/CP.20 contains a time frame up to 2030 to communicate or update by 2020 these contributions and to do so every five years thereafter pursuant to Article 4, paragraph 9, of the Agreement

Analysis of SBI.50 Options

Turning now to analyzing the proposals listed in the SBI.50 Options Note (appended below) with regard to their specific action content, the first thing that needs to be highlighted is that not all of them actually have this sort of specific action content: Neither Option 1 nor Option 4 contain references to specific NDCs or communication/updating years. As reflected in Table 1, the others do contain information as to who is meant to do what, when, and with respect to which NDC.

Given that with respect to action content, Option 3 covers Option 6, and Option 5 is covered by Option 2, there are really only two distinct Options in the SBI.50 Note with respect to actions they refer to, namely Options 2 and 3 (with their action content graphically represented in Tables 2 and 3, respectively).

Option 2:

  • Decides that common time frames … shall be five years between the end points of two successive NDCs.
  • Further decides that Parties should communicate two successive nationally determined contributions, starting in 2025, with starting points of 1 January 2031 and 1 January 2036 respectively.
  • Urges Parties to communicate and update their nationally determined contributions in 2025 and every five years thereafter, consistent with progression.

Option 3 (= continue with status quo):

  • Invites each Party to communicate by 2025 a nationally determined contribution with a time frame up to 2035 or 2040.
  • Requests:
  1. those Parties whose nationally determined contributions contain a time frame up to 2035 to communicate by 2030 their respective new nationally determined contributions with a time frame up to 2040; and
  2. those Parties whose nationally determined contributions contain a time frame up to 2040 to communicate or update by 2030 these nationally determined contributions.

Table 3.a illustrates the action content of Option 3, and Table 3.b illustrates at first sight that Option 3 is simply the continuation of the status quo as prescribed in §23 and §24 of Decision 1/CP.21. 

The GAC as Synthesis Option


The Glasgow Ambition Cycle is a proposal with a pedigree reaching beck to before Paris (see Müller et al. 2014). It first appeared in its current formulation it first appeared in an eponymous OCP blog post

The Glasgow Ambition Cycle:

  1. Request Parties to communicate by 2025 a nationally determined contribution with a time frame up to 2035, and to do so every five years thereafter, pursuant to Article 4, paragraph 9, of the Agreement
  2. Also request Parties to consider in 2025 updating any nationally determined contributions communicated before, and to do so every five years thereafter

Table 4.a illustrates the minimal action content of the GAC. Table 4.b illustrates a slightly more For more on this variant, elaborate variant, with an additional (first) communication of a 2040 NDC in 2025. Nothing in the GAC forbids such an addition, but it is important to stress that this addition is purely voluntary and not required by the GAC language.

Prerequisites for Maximizing Ambition

In order to discuss and compare the action content of SBI.50 options and the GAC, in particular with respect to their capacity to support the enhancement of (nationally determined) ambition, we need to clarify, in this action specific context, what it is for an option to contain a ‘common’ time frame.

For the action content of proposal to enhance the impact of the Global Stock Takes and ensure comparability of ambition, it must involve synchronous NDC end-years, in the sense that all NDCs having the same end-years, which is what we mean by ‘having a common timeframe’.

If one is also intent on maximizing the potential for enhancing ambition, then it has been shown that there is also a need for

  • synchronised updating (ambition enhancement), and
  • a notification window – i.e. the time between the communication year and the end year of the preceding NDC – for (first-time) communications of at least 5 years, in order maximize the potential of the synchronised ambition enhancement.


Table 5 clearly illustrates that all three options under consideration here have notification windows of at least 5 years, and – except the status quo Option 3 – they do have a common timeframe in the above-mentioned sense. Table 5 also illustrates the way in which the GAC captures (subsumes) the other two: 

Option 2 is exactly the same as the second GAC variant discussed above (Table 4.b).

As to Option 3, Table 5 shows that: 

  1. (the basic variant of) the GAC both captures the action content of the §23 sub-Option 3.a and enhances its ambition friendliness by adding the element of synchronised updating; and 
  2. how the §24 sub-Option 3.b is contained in the GAC.b variant.

In light of this and the finding of a recent OCP Blog Post (summarised below) that the GAC not only preserves all the advantages of §24 while at the same time avoiding all its disadvantages, this finding can now be transferred to all the options (with action content) currently under consideration (i.e. listed in the SBI.50 Note)  

Selected Publications

Reverse chronological order.

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