“A one-thousand-mile journey starts from the first step.”1


At COP21 in December 2015, states concluded negotiations for a new agreement, the Paris Agreement, under the auspices of the United Nations Framework Convention on Climate Change ("UNFCCC").2 The Agreement’s express aim is to “strengthen the global response to the threat of climate change.”3 The above-cited observation made by China in its Intended Nationally Determined Contribution ("INDC"), submitted in June 2015, resonates with the final outcome of those negotiations in a number of ways.

First, as UNFCCC Parties have recognized, there is a very long way to go if the aims of the UNFCCC, and now the Paris Agreement itself, are to be met. Negotiating states emphasized with “serious concern” the urgent need to address the “significant gap” between the aggregate effect of Parties’ mitigation pledges and the aggregate emission pathways consistent with holding the increase in the global average temperature to “well below 2°C above pre-industrial levels” and with “pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels.” 4 Second, and in view of what remains to be accomplished in the light of this gap, the direction of travel from this point on must be continuously forward facing. This is underscored by the references to progress found in the text, including the recognition of the need for “an effective and progressive response” to the urgent threat of climate change.5 Third, the pace of the journey must be increased if the distance is to be covered in the time available. If the Parties are indeed to prevent dangerous interference with the climate system, emissions must peak “as soon as possible,” followed by “rapid reductions,” so as “to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century, on the basis of equity, and in the context of sustainable development and efforts to eradicate poverty.” 6

Recognition of the first element, the significant gap, is embedded both in the COP Decision by which UNFCCC Parties adopted the Paris Agreement and in the Preamble to the Agreement, and is based on analysis contained in the Assessment Reports (AR) of the International Panel on Climate Change ("IPPC")7 and in the Emission Gap Reports published by the United Nations Environment Programme ("UNEP").8 These “gap” reports make reference to the IPCC ARs and, in particular, to the scenarios setting out likelihood of temperature change under certain emission pathways. The “significant gap” was confirmed in the Synthesis Report issued by the UNFCCC Secretariat in October 2015.9

The second element, the “progressive” direction of travel, developed from a recognition that efforts to address climate change must be ratcheted up if Parties are to make up the distance between where they are now and where they need to be in the near future in order to meet the agreed temperature goals. The third element, pace, is addressed in part through procedural mechanisms for review and transparency which should ensure that political pressure for effective and ambitious action is sustained and that the individual efforts, on which the collective effort is based, will remain subject to peer pressure. All the time, reference must be made to the evolving “best available science.” This Chapter focuses primarily on the second element, the direction of travel, secured by various references to progress and progression. In order to assess the legal weight of those “progressive” provisions however, it is necessary to place them within the context of the other two elements: the distance to be travelled and the pace at which the journey must be made. For the fainthearted or footsore, the words contained in the Chinese INDC remain relevant encouragement.

These three elements: the gap in collective effort, the need for a progressive direction of travel and the need for an accelerated pace towards a low carbon economy are all anchored in detailed scientific analysis published by the IPCC and UNEP. While the language in the Paris Agreement is sometimes framed in fairly general terms, it should be remembered that the science which underpinned the negotiations (and the evolution of the UNFCCC regime as a whole) is carefully and continuously calibrated in terms of emission pathways, likely degrees of warming and the likely [Page85:] impacts of global warming. The Agreement requires Parties to take individual and collective action in relation to mitigation and adaptation on the basis of “best available science”10 and this must inform the interpretation of the more general language, for example in relation to peaking of emissions “as soon as possible.”11

In considering the legal requirements for a progressive approach, it is also important to note the differentiation which is made between developed and developing countries: the Parties to the Agreement are to be guided by the principles of the Convention, including equity and common but differentiated responsibility and respective capabilities ("CBDRRC").12 It also explicitly calls on developed countries to take the lead, both in relation to mitigation and in mobilizing climate finance.13 The implications of this differentiation, less rigid than that applied under the UNFCCC and its Kyoto Protocol,14 for measuring progress are explored further below.

This strengthened response must be assessed in comparison with the overall impact of the Kyoto Protocol.15 Widely criticized as having failed to deliver a meaningful cut in emissions,16 it is clear that the new Agreement must deliver more in terms of emissions cuts and must also effectively address adaptation and the mobilization of finance in a way that Kyoto did not. The new architecture of Paris, with its “hybrid” combination of nationally determined contributions and internationally established frameworks for transparency and stocktaking, potentially garners wider participation and accountability in relation to mitigation whilst also strengthening international action on adaptation, as well as addressing the contentious issue of loss and damage under the Warsaw International Mechanism. All these strands will be the subject of ongoing development and assessment against the background of the need to address pre-2020 ambition in view of the uncertainty as to whether the Doha amendment to the Kyoto Protocol will enter into force.17 The specific issue addressed in this Chapter is the potential for a “progressive approach” to emerge as an important organizing legal principle amidst the varied efforts to strengthen the global response to climate change.


To assess the impact of a progressive approach, it is essential to bear in mind the greater clarity brought by the Paris Agreement as to the destination the Parties are heading towards. Article 2(1) of the Agreement confirms what was already laid down in Article 2 of the Convention, that the ultimate aim of the new Agreement (as a related legal instrument) is the same as that of the Convention itself, namely: “to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.” The Paris Agreement, “in enhancing the implementation of the Convention, including its objective, aims to strengthen the global response to the threat of climate change, in the context of sustainable development and efforts to eradicate poverty.”

The provisions of the Agreement thus fall to be considered in the light of the UNFCCC objective, together with the new specific aim of establishing a strengthened response to the threat of climate change.

Well before the adoption of the Paris Agreement, the Parties to the UNFCCC had sought to clarify, in more quantitative terms, what would be required to fulfil the ultimate objective laid down in Article 2 UNFCCC. In 2010, having regard to the scientific findings published by the IPCC in its AR4, the Parties agreed to be more explicit as to the action required to meet this goal, when they agreed at Cancun18 that “deep cuts” in emissions were required: “with a view to reducing global greenhouse gas emissions so as to hold the increase in global average temperature below 2 degrees above pre-industrial levels” and that “Parties should take urgent action to meet this long term goal, consistent with science and on the basis of equity …” .19

In AR5, the IPCC concluded that:

... if concentrations of greenhouse gases in the atmosphere have stabilized to about 450 ppm in 2100, there is a 66% chance that the rise of the global temperature will not exceed 2°C. In order to achieve a concentration level of 450 ppm in 2100, the global greenhouse emissions in 2050 will have to be 40 to 70% lower than those in the year 2010. The total of emissions will have to have been reduced to zero or even to below zero (as compared to the comparative year) by 2100.20

Many climate vulnerable developing countries, small island states and others maintained that the 2°C goal was insufficient to fulfil the UNFCCC objective and should be replaced by the more ambitious target of limiting the rise in global average temperature to 1.5 degrees above pre-industrial levels, which is what is required if their territories are not to be destroyed or severely affected by inundation and other adverse impacts.21 At COP21, these countries, represented by AOSIS and the Climate Vulnerable Forum in particular, came together to push successfully for the more ambitious target and the urgent peaking of emissions.22


This more ambitious goal requires a lower carbon concentration by the end of the century. The IPCC stated in AR5 that: “Mitigation scenarios in which temperature increase is more likely than not to be less than 1.5°C ... by 2100 are characterized by concentrations in 2100 of below 430 ppm CO2eq...”.23

The IPPC has also considered the implications of delaying mitigation efforts on the possibility of keeping the global average temperature rise to below 2 degrees:

Delaying mitigation efforts beyond those in place today through 2030 is estimated to substantially increase the difficulty of the transition to low longer-term emissions levels and narrow the range of options consistent with maintaining temperature change below 2°C relative to pre-industrial levels (high confidence)24 [emphasis added]

The first UNEP Emissions Gap Report, published in 2010, considered whether the pledges made by states pursuant to the 2009 Copenhagen Accord were sufficient to limit global warming to 2 degrees or 1.5 degrees. The report concluded that, under the lowest ambition pledges, a significant gap would exist by 2020 between what was required to limit temperature rise to 2 degrees and the likely temperature rise. It also found that, even if more ambitious policies were put in place, a gap of some 5GT would still exist, taking countries to only 60% of what was required. The initial reference point for the assessment of the emissions gap was the IPCC’s 2007 AR4, in which it was suggested that a reduction of 25-40% by 2020 was required compared to 1990 levels.25 The 2014 UNEP Emissions Gap report had a different focus from previous years. While it updated the 2020 emissions gap analysis, it also gave particular attention to the implications of the global carbon dioxide emissions budget for staying within the 2°C limit beyond 2020. The Report stated that it did so “because countries are giving increasing attention to where they need to be in 2025, 2030 and beyond.” The report also took into account the findings relating to an emissions budget in AR5.26

In the lead up to COP21, the UNFCCC Secretariat produced an analysis of the aggregate effect of the 119 Intended Nationally Determined Contributions ("INDCs") communicated by 1 October 2015 (the Synthesis Report).27 The report provides an estimate of the aggregate greenhouse gas ("GHG") emission levels in 2025 and 2030 resulting from the implementation of the INDCs. As explained in the Report, not all Parties had communicated an INDC by 1 October 2015, and not all of the INDCs cover all gases and sectors. In order to arrive at a global estimate of emissions in a certain year therefore, the IPCC reference scenarios were used to estimate the emissions not covered by the INDCs until 2030.28 The Synthesis Report explains how differences in approach were taken into account in determining the aggregate contribution of the pledges which ranged from pledges based on reduction relative to business as usual ("BAU") to absolute emission targets.29

There is thus a clear context, based on detailed scientific and technical assessment at the international level, for the concerns reflected in the text of the new agreement. The Parties to the Convention noted:

… with concern that the estimated aggregate greenhouse gas emission levels in 2025 and 2030 resulting from the [INDCs] do not fall within least-cost 2 ˚C scenarios but rather lead to a projected level of 55 [GT} in 2030, and also notes that much greater emission reduction efforts will be required than those associated with the [INDCs] in order to hold the increase in the global average temperature to below 2˚C above pre-industrial levels by reducing emissions to 40 GTs, or to 1.5˚C above pre-industrial levels by reducing to a level to be identified in the special report referred to in paragraph 21 below.30 [emphasis added]

The combination of the more specific and ambitious temperature goals set out in Article 2 to the Agreement, together with the clear recognition that Parties need urgently to increase their efforts to reduce emissions within a specific quantitative framework based on detailed scientific assessment is critical to the interpretation of the new agreement. It is in the light of these two elements that the various textual references to the need for a “progressive” approach and the procedural requirements for reviewing state contributions to the collective effort should be understood. The raison d’etre of the Paris Agreement, to strengthen the global response to the threat of climate change, is to be evaluated by reference to the temperature goals in Article 2 and by other specific markers in the text of the agreement.

It is also important that this strengthened response has three key elements, as indicated in Article 2:

  • Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change;
  • Increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience and low greenhouse gas emissions development, in a manner that does not threaten food production;
  • Making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development


Thus the need to address the adaptation gap also identified by UNEP31 and to introduce a more robust legal framework for securing climate finance are placed alongside the temperature goals. As discussed below, the Agreement also applies a progressive approach to these two elements, in addition to the progressive language that attaches to the need for emissions cuts. The interlinked three elements are all an essential part of the new strengthened response to climate change.

Direction of Travel: Forward Not Backward

Before considering the forward-facing legal implications of a progressive approach, it is important to note that this language also implies that states cannot move backwards. The Paris Agreement’s requirements for progression necessarily imply that Parties may not act regressively, or even stand still, beyond what is permitted in the Agreement. This resonates with a more general recent discussion as to an emerging principle of non-regression.32 In 2011, the European Parliament, in the context of developing a common position for the Rio+20 meeting, called for “… the recognition of the principle of non-regression in the context of environmental protection as well as fundamental rights.”33

The climate change regime, and the Paris Agreement in particular, can be said to constitute a rather specific case of the application of the non-regression approach, taking into account the express “progressive” language contained in the new Agreement, the restriction on regressive measures that such language implies and the stated objectives of both the Agreement and the UNFCCC. Scientific assessment has developed to the point where Parties have accepted overall temperature goals and the science that underlies the setting of those goals. Those goals are based upon the trajectories set out by the IPCC and UNEP,34 including the need for emissions to peak as soon as possible, and the need for rapid reductions thereafter “so as to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century.”35

Progression and its necessary corollary, non-regression, are particularly relevant in the context of climate change because of the detailed quantification both of the problem: the current and predicted levels of carbon in the atmosphere leading to the risk of dangerous anthropogenic interference with the climate system; and the solution, the cutting (and removal by sinks) of carbon emissions, in order to keep levels of atmospheric carbon to within a range which will limit global warming to a maximum of “well below” 2 degrees (and pursuing efforts to limit temperature increase to 1.5 degrees). The action taken by states can be quantified and monitored and, furthermore, any regressive action, such as the failure to cut emissions as agreed, has an impact on all other states as it undermines the action that they have taken.

In AR5, the IPCC confirmed that “Multiple lines of evidence indicate a strong, consistent, almost linear relationship between cumulative CO2 emissions and projected global temperature change to the year 2100” and went on to note:

Multi-model results show that limiting total human-induced warming to less than 2°C relative to the period 1861–1880 with a probability of >66% would require cumulative CO2 emissions from all anthropogenic sources since 1870 to remain below about 2900 GtCO2 (with a range of 2550 to 3150 GtCO2 depending on non-CO2 drivers). About 1900 GtCO2 had already been emitted by 2011.36

Thus the total global cumulative emissions since 2011 that are consistent with a global average temperature rise of less than 2°C above pre-industrial levels at a likely (>66 per cent) probability is 1,000 Gt CO2. The IPCC has adjusted this amount down to 800 billion tonnes in view of additional warming non carbon dioxide factors. There is thus “a global carbon budget.”37

In relation to the costs of delay in cutting emissions in line with the carbon budget identified by the IPCC, the Governor of the Bank of England referring to AR5 and the Stern Review, pointed out that: “As risks are a function of cumulative emissions, earlier action will mean less costly adjustment.”38

Thus the context for the adoption of the Paris Agreement was a quantified scientific assessment of the likelihood of limiting global average temperature rise to the level agreed by the Parties, by reference to annual GHG emission levels, CO2eq concentration levels and the impact of delaying peak emissions. This in turn provides the context for the various requirements to act progressively which appear in the Paris Agreement.

Progress in the Paris Agreement

In the Preamble to the Paris Agreement, Parties recognize “the need for an effective and progressive response to the urgent threat of climate change on the basis of the best available scientific knowledge.” There then follow a number of further substantive references to progression. Article 3 requires Parties to undertake and communicate ambitious efforts with a view to achieving the purpose of the Agreement and then provides that: “The efforts of all Parties will represent a [Page88:] progression over time, while recognizing the need to support developing country Parties for the effective implementation of this Agreement.”

Thus the framework for individual and collective action in relation to mitigation, adaptation and the mobilization of climate finance is buttressed by an overarching requirement for a progressive response, both individual and collective. It is of course the case that some of the actions to which progressive action is attached are couched in soft, or less than hard edged language: “aim to reach”; “intends to achieve”; “pursue mitigation measures” and “should take the lead.” However the accompanying hard edged requirements for preparation, communication and maintenance of NDCs39, transparency40 and review41, together with the integration of references to “best available science” and progress add rigour and structure to these substantive requirements. Further mandatory force is introduced by the principles which form part of the new regime, as discussed below. “Progress” in the Paris Agreement is not motherhood and apple pie, it has a very specific and measurable meaning.

As to mitigation, Article 4(1) provides:

In order to achieve the long-term temperature goal set out in Article 2, Parties aim to reach global peaking of greenhouse gas emissions as soon as possible, recognizing that peaking will take longer for developing country Parties, and to undertake rapid reductions thereafter in accordance with best available science, so as to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century, on the basis of equity, and in the context of sustainable development and efforts to eradicate poverty. [emphasis added]

Parties were not able to agree on a specific timescale for peaking of emissions. However, the imperative of peaking “as soon as possible,” is based on the detailed scientific analysis presented by the IPCC, particularly in AR5 which confirms that:

Delaying mitigation efforts beyond those in place today through 2030 is estimated to substantially increase the difficulty of the transition to low longer-term emissions levels and narrow the range of options consistent with maintaining temperature change below 2°C relative to pre-industrial levels.42

The reference in Article 4(1) to the need for rapid reductions thereafter “in accordance with best available science” links these requirements to the ongoing work of the IPCC, which will inform the global stocktake provided for in Article 14, as well as the facilitative dialogue scheduled to take place in 2018.43 The IPCC has also been invited by the Convention Parties to produce a special report in 2018 on the impacts of a 1.5 degrees temperature rise and on likely pathways to limit the rise in temperature to 1.5 degrees.44 The inclusion in Article 4(1) of a specific goal of balancing emissions by the second half of the century provides a further key benchmark against which to assess progress towards the ultimate goal of the Convention and Article 2 of the Agreement.

Article 4(2) requires each Party to prepare, communicate and maintain nationally determined contributions ("NDCs”) which it intends to achieve. Parties are to “pursue domestic mitigation measures, with the aim of achieving the objectives of such contributions.” Article 4(3) requires that: “Each Party’s successive [NDC] will represent a progression beyond the Party’s then current [NDC] and reflect its highest possible ambition, reflecting its [CBDRRC], in the light of different national circumstances.”

The language of this provision appears to be robust, particularly the reference to maintenance of NDCs which goes beyond the (arguably) purely procedural steps of preparing and communicating contributions. Clearly the underlying duty of good faith which applies generally under treaty law would require states to perform these actions in a meaningful way such that what is “intended” is both genuinely intended and steps taken towards achievement. There is scope for discussion as to the circumstances, if any, in which a state might depart from an NDC, but given the requirement to maintain the NDC and to enhance ambition, both on the five-year cycle and in respect of any interim adjustment, Article 4 clearly requires more than a mere declaration of intent. Moreover, all national actions contribute to the collective effort to meet quantified temperature goals. While there may be scope for debate as to the legal constraints on policy changes which affect the delivery of the NDCs, for example where action in one sector is “set off” against a deferral of action in another, it appears that states are constrained in the extent to which they discard or retreat from these contributions as this will impact on the collective response to climate change. At the very least there is accountability for delivering national contributions in the sense of a requirement to make the contribution in a transparent and timely way and to account for any success, failure or delay to other Parties. The issue of compliance under the Paris Agreement is to be addressed by states at a meeting in September 2016.

There is differentiation in the requirements for mitigation:

Developed country Parties should continue taking the lead by undertaking economy-wide absolute emission reduction targets. Developing country Parties should continue enhancing their mitigation efforts, and are encouraged to move over time towards economy-wide emission reduction or limitation targets in the light of different national circumstances.45


Support shall be provided to developing country Parties for the implementation of this Article, in accordance with Articles 9, 10 and 11, recognizing that enhanced support for developing country Parties will allow for higher ambition in their actions.46 [emphasis added]

The pace at which developing countries move towards economy-wide emission reductions or limitation targets is here closely tied to levels of support. The environmental impact of delay in collective action has been examined by the IPCC, as discussed below. The added costs of delay in environmental, social and economic terms provides context for the interpretation of this provision and the extent to which it leverages greater mobilization of finance for developing countries.

The NDCs provided for in the Paris Agreement emerged from the decision to invite all parties to submit INDCs before the final negotiations at COP21. The INDCs, whose potential future legal status or relevance had not yet been determined, were however submitted within a guiding framework which included references to progression. At the 2013 Warsaw COP, it was agreed that Parties in a position to do so should submit INDCs by March 2015: “in a manner that facilitates the clarity, transparency and understanding of the intended contributions, without prejudice to the legal nature of the contributions.”47 At COP20 the following year, it was decided to call on Parties to submit INDCs that were fair and ambitious and that would “represent a progression beyond the current undertaking of that Party.”48

Calls for a “ratcheting up mechanism” in relation to the INDCs were widely expressed in the negotiations leading up to Paris: “To ensure the Paris agreement does not lock in inadequate INDCs a strong ratcheting-up mechanism is vital.” 49 The references to progression in the final text can be seen in part as a response to those calls for ratcheting up. Under the Paris Agreement, NDCs are to be submitted every five years50 and the scope for adjustment during the cycle is addressed in Article 4(11): “A Party may at any time adjust its existing [NDC] with a view to enhancing its level of ambition, in accordance with guidance adopted by the Conference of the Parties serving as the meeting of the Parties to the Paris Agreement.”

Thus, while there is scope for national discretion in relation to many aspects of the NDCs, including the selection of sectors and policies to achieve a mitigation effort that is sufficiently ambitious, the direction of travel is clearly set by the Agreement. Each NDC must represent a progression beyond its predecessor and interim adjustment can only be made in order to enhance the level of ambition. This means that developed countries must progressively increase their economy-wide absolute emission reduction targets and developing countries must progressively enhance their mitigation efforts, and are encouraged to move progressively over time towards economy-wide emission reduction or limitation targets “in the light of different national circumstances.” In the light of the significant gap acknowledged by the Parties, progression must be understood as reflecting the need to catch up collectively whilst at the same time maintaining fairness and equity in the assessment of individual contributions to the collective effort.

Under Article 9 of the Agreement, developed country Parties are required to provide financial resources to assist developing country Parties with respect to both mitigation and adaptation in continuation of their existing obligations under the Convention, while other Parties are encouraged to provide or continue to provide such support voluntarily. Developed countries are to continue to take the lead in mobilizing climate finance from a wide variety of sources and “such mobilization of climate finance should represent a progression beyond previous efforts.”51

The Agreement’s requirements in relation to NDCs, adaptation and the mobilization of climate finance all fall to be assessed under the global stocktake provided for in Article 14. The first such stocktake, which will be conducted by the parties, will take place in 2023 (and then every five years thereafter unless otherwise decided) but will be preceded by a “facilitative dialogue” in 2018. In relation to the stocktake itself, Article 14 provides that the Meeting of the Parties shall:

… take stock of the implementation of this Agreement to assess the collective progress towards achieving the purpose of this Agreement and its long-term goals... It shall do so in a comprehensive and facilitative manner, considering mitigation, adaptation and the means of implementation and support, and in the light of equity and the best available science.

The outcome of the global stocktake “shall inform Parties in updating and enhancing, in a nationally determined manner, their actions and support in accordance with the relevant provisions of this Agreement, as well as in enhancing international cooperation for climate action.” Given that some of the NDCs address adaptation as well as mitigation, the progressive response laid down in the Agreement clearly encompasses measures taken in relation to adaptation, as well as mitigation measures. The Global Stocktake is to review the overall progress made in relation to the global goal on adaptation.52 The maintenance of the balance between fairness and ambition reflected in Article 4 will be relevant to the global stocktake and may require a careful audit of the extent to which support has been provided to developing countries seeking to raise their level of national ambition. The task for Parties in 2023 will be to identify barriers to closure of the gap with a view to addressing them as soon as possible, perhaps some barriers can be pre-empted or reduced if effective use is made of the facilitative dialogue process in 2018.


Underpinning these requirements for national ambition, progressive steps and the collective review, represented both by the 2018 facilitative dialogue and by the global stocktake, is the transparency framework laid down in Article 13:

In order to build mutual trust and confidence and to promote effective implementation, an enhanced transparency framework for action and support, with built-in flexibility which takes into account Parties’ different capacities and builds upon collective experience is hereby established.

The arrangements for transparency will clearly be critical in allowing Parties to have confidence in each other individually and collectively and to meet best practice or learn from other’s experience in an open way. Progress can only be measured if there is commitment to transparency.

4.1 Guiding Principles under the Paris Agreement/Convention

The normative and legal framework from which the Paris Agreement is constructed includes those principles which are applied under the Convention, as is made clear in the Preamble:

In pursuit of the objective of the Convention, and being guided by its principles, including the principle of equity and [CBDRRC], in the light of different national circumstances.

This is consistent with the language of Article 2 UNFCCC which extends the ultimate objective of the Convention to related legal instruments. The principles laid down in the UNFCCC are to guide the achievement of the ultimate objective and are therefore clearly relevant to the implementation of the Paris Agreement. A number of these principles support the requirements for a progressive response set out in Agreement, as discussed below. More broadly, it can be argued that a progressive approach, and within that, the restriction of regressive action by states, are implicit in these principles, taken together with the ultimate objective.

Article 3 UNFCCC lays down a number of key principles which shall guide the action taken by Parties to achieve its objective and implement their responsibilities. They include: intergenerational equity, CBDRRC, the principle that developed country Parties should take the lead in combating climate change, that full consideration should be given to the specific needs and special circumstances of developing country Parties, precaution and sustainable development.

Thus, as a matter of international treaty obligation, the assessment of progress (or the lack of it) on the part of Parties to the Paris Agreement will fall to be assessed by reference to these guiding principles. It is notable that the guidance laid down in Article 3 relates not only to environmental impacts, but also to the social and economic aims and impacts of state actions (the “socio-economic context,” “sustainable economic growth and development,” “economic development” and so on). This reinforces the relevance of the progressive approach, not only to mitigation per se but also to adaptation and to the provision of climate finance, given the clear socio-economic relevance of both. A failure progressively to support action to tackle the impacts of climate change which then exacerbates vulnerability and economic deprivation would not be in accordance with the Convention’s guiding principles of equity and sustainable development, for example. Moreover, states must ensure that progress in securing equity and sustainable development is consistently maintained, including by securing concrete progress in responding to adaptation needs.

4.1.1 The Responsibility Not to Cause Damage to the Environment of Other States

The eighth recital to the Convention recalls:

… that States have, in accordance with the Charter of the United Nations and the principles of international law, the sovereign right to exploit their own resources pursuant to their own environmental and developmental policies, and the responsibility to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction;

As the International Court of Justice (ICJ) has confirmed, this principle (commonly referred to as the “no harm principle”) is in any event now part of the corpus of international law relating to the environment.53 The application of this principle to the issue of climate change is likely to form part of any request for an Advisory Opinion to the International Court of Justice on state responsibilities in this area.54

The Paris Agreement indicates that state responsibility in the area of climate change includes the requirement to act on the best available science (Articles 4(1), 7(5) and 14(1)) and also to act progressively (Articles 3, 4(3) and 9(3)) to ensure that damage is prevented. These legal duties are particularly relevant to the issue of delay in cutting emissions (and in providing climate finance to states who require support to implement their NDCs). As discussed above, the IPCC AR’s and UNEP’s series of Emission Gap reports indicate the risks of delay in terms of increased cost and the resulting threat to achieving the required deep cuts if the objectives of the Convention, and now the Agreement, are to be met.


States which reverse previous commitments, or which do not (at least) increase their contributions in line with the five year NDC cycle, or which do not act ambitiously in setting emission targets for 2020 or 2030, jeopardize, not only their own individual contribution to addressing climate change but also the collective efforts of other states seeking to prevent dangerous interference with the climate system. Such states also potentially increase the costs of meeting the aim of the Convention for all states. The Paris Agreement is designed to keep states on track and to restrict “backsliding.”

This raises a number of issues which the Parties may wish to address collectively in the form of guidance to be endorsed by the COP55 including: what are the consequences for a state, and for the parties as a whole, in cases where regressive action is taken by a state or even in cases where state action remains static? How is progress to be measured in relation to mitigation and adaptation? What are the requirements for progressive mobilization of climate finance? This will be relevant to the issue of compliance to be discussed by states in the lead up to entry into force of the Agreement.

4.1.2 Prevention

The framing of Article 2 UNFCCC is centred on the prevention of dangerous anthropogenic interference with the climate system. This can be seen as a specific expression of the general principle of prevention which permeates international environmental law.

It might seem self-evident that the prevention principle, which is reflected in many international treaties and other instruments as well as in the European Union (EU) treaty provisions on environmental protection,56 restricts regressive conduct since such a restriction will, of itself, require that harm be prevented: it will prohibit or restrict the lowering of environmental quality standards and it may arguably prohibit or restrict action which will render it more difficult and/or costly to achieve environmental goals. In the context of climate change and the strengthened response required by the Paris Agreement, the best available science on which the Parties have relied in concluding the Agreement (and in accordance with which they have bound themselves to act, going forward) has clearly indicated that delay in cutting emissions, delay in peaking emissions, lack of ambition and the failure to address the “emissions gap” will jeopardize the Convention’s ultimate aim of preventing dangerous anthropogenic interference with the climate system.

In ICJ Argentina v Uruguay (Pulp Mills), the ICJ referred to the general duty of states to prevent pollution by acting with due diligence and “vigilance” in ensuring the enforcement of environmental measures:

… the obligation … to prevent pollution by prescribing appropriate rules and measures is an obligation to act with due diligence in respect of all activities which take place under the jurisdiction and control of each party. It is an obligation which entails not only the adoption of appropriate rules and measures, but also a certain level of vigilance in their enforcement and the exercise of administrative control applicable to public and private operators, such as the monitoring of activities undertaken by such operators, to safeguard the rights of the other party.57

… the principle of prevention, as a customary rule, has its origins in the due diligence that is required of a State in its territory. It is “every State’s obligation not to allow knowingly its territory to be used for acts contrary to the rights of other States” ... A State is thus obliged to use all the means at its disposal in order to avoid activities which take place in its territory, or in any area under its jurisdiction, causing significant damage to the environment of another State …58

Parties to the Paris Agreement are under a duty to act with due diligence in adopting and enforcing the policies and measures on which they base their NDCs to the collective effort to prevent dangerous interference with the climate system. It might be argued that the vigilance to which the Court referred is particular relevant to climate change, given the complexities and the need to adapt to changes in scientific understanding. States are also under a duty to cooperate, within the specific framework laid down in the Agreement, so as to fulfil the requirement to prevent such dangerous interference. To be effective, the global stocktake should assess the due diligence and vigilance with which parties have implemented their NDCs. Where states have stated that they will reduce emissions the issue will be what action has been taken and resources deployed to deliver that part of the NDC. This may include issues of enforcement of national law and the establishment of adequate administrative systems by which to monitor delivery at the national level.

4.1.3 Precaution

Also relevant in this context is Article 3(3) UNFCCC:

The Parties should take precautionary measures to anticipate, prevent or minimize the causes of climate change and mitigate its adverse effects. Where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing such measures, taking into account that policies and measures to deal with climate change should be cost-effective so as to ensure global benefits at the lowest possible cost … [Emphasis added]


The greater precision with which scientists can now model the likely impacts of rising carbon emissions can be argued to diminish, but certainly not remove, the need to act with precaution, as there are still areas of scientific uncertainty, for example those reflected in the percentage assessments of probability in the ARs. Under conditions of greater scientific certainty, the preventive principle becomes more directly relevant. Non-regression is implicit as an inherent element of precaution, as well as prevention, particularly when taking into account the specific obligation placed on states under the Paris Agreement to have regard to the “best available science.” In circumstances of uncertainty, but where there is a risk of serious harm, measures must be taken and a withdrawal of such measures or a lowering of risk management would infringe the precautionary principle. To the extent that there remains any uncertainty, for example as to the “carbon budget” which remains if temperature goals are to be met, precaution would require states to operate within that budget unless further scientific assessment indicates that the budget is different. In view of the evolution of scientific understanding thus far, and the current state of technology for sequestering carbon, it does not appear likely that the budget will be revised downwards, though a number of different approaches have been adopted to the setting of the budget.59

In the context of the NDCs, precaution should guide the action of states and may have the following implications: increasing levels of ambition in line with best available science and the availability of new technology and ensuring that peaking “as soon as possible” is interpreted rigorously so as to ensure that measures are cost effective, given the likely costs of delay as discussed above.

4.1.4 Sustainable Development and Equity

Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”60

The UNFCCC puts equity at the heart of the legal framework for addressing climate change.61 The Paris Agreement does not adopt the same differentiation in terms of mitigation obligations as was applied under the Kyoto Protocol, but differentiation between developed and developing countries is maintained, for example in relation to the NDCs. This is consistent with the principle of equity reflected in Article 3 UNFCCC. Equity between states and generations remains a guiding principle for the Paris Agreement within the context of an evolved scientific understanding as to the “carbon budget” which remains available if the ultimate goal of the Convention is to be achieved, and taking into account that states must act progressively (including in relation to the provision of climate finance).

State action, or inaction, which narrows the choices available to future generations and jeopardizes the resource base on which they seek to exercise choices runs counter to the intergenerational equity principle as reflected in Article 3 UNFCCC and, by delaying effective action, jeopardizes the aim of the Convention. Adverse distributional impacts caused by a failure to take progressive action may also be characterized as a breach of the principle of equity, particularly given the disparities in vulnerability between states.

The Duty to Cooperate and Progress

All international environmental regimes are based upon cooperation. In Pulp Mills the ICJ highlighted the relationship between the procedural and substantive aspects of cooperation in a bilateral regime established to protect the River Uruguay:

… it is by co-operating that the States concerned can jointly manage the risks of damage to the environment that might be created by the plans initiated by one or other of them … through the performance of both the procedural and the substantive obligations laid down … whereas the substantive obligations are frequently worded in broad terms, the procedural obligations are narrower and more specific, so as to facilitate … implementation … through a process of continuous consultation between the parties concerned. The Court has described the régime … as a “comprehensive and progressive régime” … since the two categories of obligations mentioned above complement one another perfectly, enabling the parties to achieve the object of the Statute which they set themselves in Article 1.62

In the case of climate change, there was early and explicit recognition that effective action could only be taken on a cooperative and collective basis. The Convention acknowledges both that “change in the Earth’s climate and its adverse effects are a common concern of humankind” and that “the global nature of climate change calls for the widest possible cooperation” by all countries and their participation in an effective and appropriate international response, in accordance with their [CBDRRC] and their social and economic conditions. Article 3(5) UNFCCC provides that: “The Parties should cooperate to promote a supportive and open international economic system that would lead to sustainable economic growth and development in all Parties, particularly developing country Parties, thus enabling them better to address the problems of climate change …”


The Paris Agreement, in aiming for a strengthened response to climate change, has laid a basis for cooperation which, while relying on national contributions determined by state parties, introduces a system of transparent review and periodic stocktaking in which Parties must cooperate fully if their efforts are to be effective and meaningful. Accordingly the language for these aspects of the regime is largely mandatory.63 Moreover, the references to progression discussed above form part of the cooperation which is required, underpinned by transparency, ambition and the need to establish a common accounting methodology. Cooperation will range from the highly technical: devising and applying a common methodology for accounting and reporting, to the more macro-level ensuring that national policies do not undermine the progress pledged under the NDCs, either by the pledging state or by others.

There is a debate to be had as to the implications of Paris for the tendency of emissions to be “outsourced” from developed to developing states. If the contribution pledged in the NDC is, in effect, offset by emissions shifting elsewhere as “consumption emissions” that may be said to breach the progressive and cooperative approach outlined in the text of the Agreement. At the very least, the duty to cooperate and to act ambitiously and progressively can be said to require that such shifts are audited and their impact factored in to both the individual and collective review of effort in the context of the facilitative dialogue and the global stocktakes which are to review progress. This is discussed further below.

Duty of Good Faith

Given the carefully crafted balance achieved in the Paris Agreement between action to be initiated and “determined” at the national level and the establishment of an international framework that will safeguard the collective effort, the duty of good faith is particularly relevant. This “hybrid” arrangement will only be effective if parties and other stakeholders have confidence that national and international law and policy are meshing in a coherent way to deliver the goals of the Agreement.

National contributions are the building blocks of the collective international effort to reduce emissions, to ensure that they peak as soon as possible and to secure rapid reductions thereafter. They are also components of the international effort to secure adaptation and protect the lives, health and well-being of the most vulnerable. Mitigation and adaptation must be supported by the mobilization of climate finance on a sufficient scale and the Agreement recognizes this in its stated aim and in Article 9. The mutual trust required to make these three elements effective can only be achieved if parties act and are seen to act, in good faith, a duty which applies to “all obligations established by a treaty, including procedural obligations which are essential to co-operation between States.” 64 In Pulp Mills the Court recalled that: “One of the basic principles governing the creation and performance of legal obligations, whatever their source, is the principle of good faith. Trust and confidence are inherent in international co-operation …” 65

Signatories to the Paris Agreement, and those states which have expressed their consent to be bound by the treaty, pending its entry into force, have a duty not to defeat its object and purpose, as indicated in Article 18 of the Vienna Convention on the Law of Treaties.66 This raises the question of what steps such states should take, pending ratification of the Agreement. It is arguable that they should not jeopardize the collective effort by departing regressively from pledges already made in the form of INDC’s, since this risks defeating the object and purpose of the Agreement by rendering it more difficult and/or costly to meet its mitigation and adaptation goals. Regressive steps pending the entry into force of the agreement may also create a degree of uncertainty among the Parties that will undermine their ability to agree further measures at domestic and international levels. The negotiations were based in large measure on scientific analysis of current emissions levels, the pledges made by states, the likely impact of those INDC pledges and the various scenarios set out by the IPCC. Regressing from the INDCs arguably undermines in part the basis on which agreement was reached.

Depending on the time taken for ratification, it may be argued that signatory states should go further and review their contributions progressively, in the light of best available science, so as to keep in step with state parties, and adhere to the five-year review cycle. In order to meet their Article 18 VCLT duty and permit state parties to take stock of the collective international effort, signatory states should also adhere to the transparent approach laid down in Article 13 and cooperate with the facilitative dialogue and with the global stocktake provided for in the Decision 1/CP.2167 and in Article 14 of the Agreement respectively. Regressive policies by signatory states will increase the burden placed on state parties to take correspondingly greater steps to cut emissions. A similar point was picked up prior to the conclusion of negotiations with references to “free rider states”.68



The emphasis on transparency in the Paris Agreement is buttressed by international principles governing access to information and public participation reflected in Principle 10 of the 1992 Rio Declaration and, at the regional level, by the 1998 UN/ECE Aarhus Convention on Access to Information, Public Participation in Decision-Making and Access to Justice in Environmental Matters (the Aarhus Convention). These principles are also recognized under many regional human rights regimes including the European Convention on Human Rights (ECHR).

The growing inclusion, prompted by developments at the international level, of provision for access to information, transparency and public participation in national legislation indicates that it is more likely that states which act regressively on climate change can be held to account. The application of these principles, reinforced with the transparency requirements of the new Agreement, will mean that states must acknowledge, explain and, if necessary, justify their actions. This applies both where they fail to act progressively, as the NDC process evolves, and also where they act regressively in not delivering their stated contributions. The existence of a mechanism for holding states publicly to account has a significant potential political effect, even where the requirements that states must give an account of are not all hard edged.

The Paris Agreement’s focus on progress, transparency and review also indicates that regressive policies, such as reductions in support for low carbon development, will fall to be explained and justified under principles of effectiveness and good faith as discussed above, at least to the extent that such actions undermine the nationally declared trajectory for reducing emissions.

The Legal Implications of Delay

As noted by the Dutch Court in the recent Urgenda case69, UNEP’s 2013 Emissions Gap Report outlines the adverse implications for the realization of the 2 degree target, of what are termed “later action scenarios,” in other words, relative delay in making the required cuts in carbon emissions. The consequences of such delay include: “much higher rates of global emission reductions in the medium term; greater lock-in of carbon intensive infrastructure; greater dependence on certain technologies in the medium term; greater costs of mitigation … greater risks of economic disruption and … greater risks of failing to meet the 2 degrees target.”70 In this sense, delay in cutting emissions may be said to be “regressive” both from an environmental perspective and from a socio-economic one.

The Urgenda case concerned the legality of the Dutch government’s proposed emission cuts in terms of scale and timetable under Dutch constitutional law, Articles 2 and 8 of the ECHR and the international and EU framework for climate change, including the Convention. The dispute centred on the question whether the State was falling short — as argued by Urgenda — in its duty of care by pursuing a reduction target for 2020 that was lower than 25-40%, compared to 1990. The Court, having considered AR4 and AR5, as well as decisions taken by the Parties to the Convention, concluded that this scale of reduction by 2020 was “the standard accepted in climate science and the international climate policy.”71

The Court did not explicitly refer to the non-regression principle or the need to act progressively and the case predated the adoption of the Paris Agreement and its provision for progressive action. However, there are elements of the Court’s decision, which centres on duties under Dutch constitutional law, which appear to be based on a recognition that a progressive, or at least non regressive, approach is mandated by the climate change regime, taking into account the scientific evidence. The Court noted the following:

... the Netherlands has cooperated with the decision in Cancun (2010) in which it was established that the Annex I countries at least have to realize a 25-40% reduction in 2020 … the EU has committed to a reduction target of 20% for 2020, with an increase to 30% (both compared to 1990) if other Annex I countries commit to a similar reduction target. The standard of 20% for the EU is below the 30% standard deemed necessary by scientists ... The Netherlands has committed to the EU target of 30% reduction in 2020, provided that the other Annex I countries do the same ... Up to about 2010, the Netherlands assumed a reduction target of 30% for 2020 compared to 1990, and after 2010 took on a reduction target that is derived from the EU reduction target of 20% and which is expected to result in a total reduction of 14-17% in 2020. 72 [emphasis added]

It appears that the Court took into account the Netherlands’ decision to lower the reduction target below what had originally been agreed (based on “the best available science”) in considering whether the Government had acted lawfully. The Court highlighted the principles of fairness, precaution and sustainability as laid down under the UNFCCC for establishing the scope for policy making and the duty of care under Dutch law73 and noted:

... the State has known since 1992, and certainly since 2007, about global warming and the associated risks. These factors lead the court to the opinion that, given the high risk of hazardous climate change, the State has a serious duty of care to take measures to prevent it.74


The Court then outlined the change in the policy of the Government in relation to the reduction target for 2020 and noted:

... The State has not argued that the decision to let go of this national reduction target of 30% and instead follow the EU target of 20% for 2020, compared to 1990..., was driven by improved scientific insights or because it was allegedly not economically responsible to continue to maintain that 30% target. Nor did the State issue concrete details from which it could be derived that the reduction path of 25-40% in 2020 would lead to disproportionately high costs, or would not be cost-effective in comparison with the slower reduction path for other reasons. On the contrary: the State confirmed that it would be possible for the Netherlands to meet the EU’s 30% target for 2020 provided that the condition for that target was met in the short term. Based on this, the court concludes that there is no serious obstacle from a cost consideration point of view to adhere to a stricter reduction target. 75 [emphasis added]

The Court concluded:

... that in view of the latest scientific and technical knowledge it is the most efficient to mitigate and it is more cost-effective to take adequate action than to postpone measures in order to prevent hazardous climate change. The court is therefore of the opinion that the State has a duty of care to mitigate as quickly and as much as possible.76

The Court appears to have approached the issue as one where any change of policy away from what international climate science and policy indicated was necessary would require strong justification by the state and went on to underline the principles underpinning such an approach:

Annex I countries … have taken the lead in taking mitigation measures and have therefore committed to a more than proportional contribution to reduction, in view of a fair distribution between industrialized and developing countries. Due to this principle of fairness, the State, in choosing measures, will also have to take account of the fact that the costs are to be distributed reasonably between the current and future generations. If according to the current insights it turns out to be cheaper on balance to act now, the State has a serious obligation, arising from due care, towards future generations to act accordingly. Moreover, the State cannot postpone taking precautionary measures based on the sole reason that there is no scientific certainty yet about the precise effect of the measures. However, a cost-benefit ratio is allowed here. Finally, the State will have to base its actions on the principle of “prevention is better than cure.”

To all these principles it applies that if the State wants to deviate from them, it will have to argue and prove sufficient justification for the deviation. A justification could be the costs. The State should not be expected to do the impossible nor may a disproportionately high burden be placed on it. However, as has been considered above, it has neither been argued, nor has it become evident that the State has insufficient financial means to realize higher reduction measures...77

The state had not presented evidence on which to base a justification for the delay in taking action, to the contrary: “... the State also argues that a higher reduction target is one of the possibilities. This led the court to the conclusion ... that the State, given the limitation of its discretionary power discussed here, in case of a reduction below 25-40% fails to fulfil its duty of care and therefore acts unlawfully...”.78

The Court’s decision is currently subject to appeal by the Dutch Government.

It appears that the Court was influenced by the regressive decision to lower the reduction target without a sufficient, or any, compelling economic or other justification, and in the light of the scientific assessment presented at the international level by the IPCC and accepted by the EU. This decision, if it stands, may indicate an increased legal scrutiny of regressive decisions by states. The question remains whether the added important dimension of the progressive language and dynamic structure of the Paris Agreement will increase the legal scrutiny of regressive (or lack of progressive) action by parties.

The Right to Regulate?

United States Secretary of State John Kerry described the outcome of COP21 in the following terms:

The result will be a very clear signal to the marketplace of the world that people are moving into low carbon, no carbon, alternative renewable energy ...

Where a party to the Paris Agreement changes its national law in order to give effect to commitments made in its NDC this may have an impact on foreign investors. The question then is what are the legal implications for any potential claim by the investor of the circumstances leading up to the adoption of the Paris Agreement, including the submission of an INDC, together with the subsequent adoption of the Agreement with its requirements for the preparation, communication and maintenance of NDCs in Article 4. Where such changes adversely affects a foreign investment covered by an International Investment Agreement (IIA), the investor may argue that such action has breached the principle of fair and equitable treatment, by violating that investor’s legitimate [Page96:] expectation of the investor that national law would not change. The shift marked by Paris, and arguably by earlier events including the publication of the IPCC ARs, the UNEP Gap Reports and various decisions of the UNFCCC Parties such as the decision to negotiation a new agreement at the Durban COP can all be involved as changing the regulatory and business environment to the extent that investors have for some time been on notice of likely changes, for example in the energy sectors. Due diligence should take account of all these factors and others including the growth of climate litigation.

In Parkerings-Compagniet v Republic of Lithuania,79 the Tribunal was faced with a claim arising from a change in the legal framework for the investment that had an impact on the Claimant’s investment. The Tribunal noted:

In principle, an investor has a right to a certain stability and predictability of the legal environment of the investment. The investor will have a right of protection of its legitimate expectations provided it exercised due diligence and that its legitimate expectations were reasonable in light of the circumstances. Consequently, an investor must anticipate that the circumstances could change, and thus structure its investment in order to adapt it to the potential changes of legal environment.80

The Tribunal then went on to find however:

In 1998, at the time of the Agreement, the political environment in Lithuania was characteristic of a country in transition from its past being part of the Soviet Union to candidate for the European Union membership. Thus, legislative changes, far from being unpredictable, were in fact to be regarded as likely. As any businessman would, the Claimant was aware of the risk that changes of laws would probably occur after the conclusion of the Agreement. The circumstances surrounding the decision to invest in Lithuania were certainly not an indication of stability of the legal environment. Therefore, in such a situation, no expectation that the laws would remain unchanged was legitimate.

By deciding to invest notwithstanding this possible instability, the Claimant took the business risk to be faced with changes of laws possibly or even likely to be detrimental to its investment. The Claimant could (and with hindsight should) have sought to protect its legitimate expectations by introducing into the investment agreement a stabilization clause or some other provision protecting it against unexpected and unwelcome changes.

The record does not show that the State acted unfairly, unreasonably or inequitably in the exercise of its legislative power. The Claimant has failed to demonstrate that the modifications of laws were made specifically to prejudice its investment

There are analogies here: the Paris Agreement and the events leading up to its adoption signal international agreement to move even more decisively towards a low carbon future. All Signatories and eventually Parties to the Agreement are in this sense “states in transition.” It is also clear that the NDCs will form the basis for such a transition and will be subject to some form of international review in the form of the global stocktake. These events are well known and have been widely discussed and publicized. Those with investments in sectors likely to be affected, including in the energy or other carbon intensive sectors, may be hard pressed to argue that they have a legitimate expectation, going forward, that states will not modify their laws in this area.

In the light of the scientific evidence presented by the IPCC and UNEP, on which states based their negotiations for a strenthened response to climate change, the question, post-Paris is how the new agreement is likely to impact on investment and on potential disputes between states and investors.

The progressive approach discussed in this chapter may be invoked by states wishing to defend the implementation of their NDCs, particuarly where this entails an increased level of ambition in curbing emissions and a regular adjustment towards enhancing the level of ambition. Paris clearly provides a framework for a state’s right to regulate. States have broad discretion as to ways and means, subject to the degree of differentiation laid down in Article 4 in particular, but they are required to have regard to the best available science and they are required to act and to regulate progressively.

Paris has clearly provided a framework for action which is designed to ensure that national effort is ratecheted up but some issues remain unresolved, for example is it permissable for a state to adjust its policy by “setting off” a gain in one sector against a lack of progress in another? For example, if a state regulates emission standards for power stations but then decides not to make those standards more stringent in the next NDC cycle because it has tightened standards elsewhere, is that consistent with progression? Does the term “maintain” imply that some stability is required in relation to the NDCs and that parties agree that the collective effort will not be secured if states just switch rapidly from one policy to another. Signatory states will no doubt discuss these issues as they develop guidance on the Agreement.

Some of these issues could perhaps be pre-empted were states to adopt a declaration of their understanding as to the impact of the Paris Agreement on a state’s rights to regulate so as to maintain their NDCs in accordance with Article 4 of Paris. Any such step would lack legitimacy [Page97:] unless it was seen to be supportive of both national and individual efforts to close the gap which prompted, in large part, the framework for a strengthened response.


In the light of the overall framework of the UNFCCC, the explicitly progressive language of the Paris Agreement itself and the scientific assessment which underpins it and which formed the context for its adoption, it is clear that the new strengthened legal framework is designed to ensure that Parties do indeed ratchet up their efforts to cut emissions. The explicit recognition in the Preamble of the need to address the gaps which exist if the temperature goals are to be met is central to the interpretation of the Agreement. It is also clear however that the Agreement is intended to strengthen the legal framework for securing the support that some Parties need, in order to make appropriate individual efforts and to increase the effectiveness of the regime overall, including by securing the necessary adaptation measures to protect basic rights of those who will inevitably be affected.

Paris appears to go further than the Dutch Court in Urgenda, since there is no provision in the Agreement for a state to justify failing to act progressively (or acting regressively) in relation to mitigation, for example on grounds of cost (which the Dutch Court had at least contemplated as providing possible grounds for delaying emission reductions). The exception to this more onerous duty is arguably where a state has not received sufficient climate finance support to enable it to take the required measures. That may be the only basis to slow the pace of the journey and even then the ground must be collectively made up, in time to reach the desired goals.

“Enhanced Actions On Climate Change: China’s Intended Nationally Determined Contributions” submitted 30 June 2015, see page 5 of the unofficial translation.

New York 9 May 1992, in force 21 March 1994, 1771 UNTS 107; S. Treaty Doc No. 102-38; U.N. Doc. A/AC.237/18 (Part II)/Add.1; 31 ILM 849 (1992). In 2011 UNFCCC Parties tasked the Ad Hoc Working Group on the Durban Platform for Enhanced Action (ADP) with developing a new “protocol, another legal instrument or an agreed outcome with legal force under the Convention applicable to all Parties”, to be agreed by 2015 and come into effect from 2020, UNFCCC Decision 1/CP.17, UN Doc. FCCC/CP/2011/9/Add.1.

The Paris Agreement was adopted on 12 December 2015 at the twenty-first session of the Conference of the Parties to the UNFCCC. In accordance with its article 20, the Agreement shall be open for signature at the UN Headquarters in New York from 22 April 2016 until 21 April 2017 by States and regional economic integration organizations that are Parties to the United Nations Framework Convention on Climate Change. See Paris Agreement Article 2(1).

9th recital to the Preamble to Decision 1/CP.21.

4th recital to the Preamble to the Paris Agreement.

Article 4(1) of the Paris Agreement.

The 2013 Fifth Assessment Report is available at www.ipcc.ch/report/ar5.

The 2015 Report, the latest in the series was published by UNEP, in November 2015 (full version issued on 8 December 2015).

FCCC/CP/2015/7 Synthesis Report on the Aggregate Effect of the Intended Nationally Determined Contributions, 30 October 2015.

Article 4(1), Article 7(5) and Article 14(1).

Article 4(1) of the Agreement.

3rd recital to the Preamble to the Agreement.

Article 4(4) and Article 9(3) of the Agreement.

The UNFCCC lists in Annex I those countries (mainly developed countries) taking on more stringent commitments to limit emissions and the Kyoto Protocol places then requirements on those Annex I countries to undertake binding emissions cuts (based on the quantified emission limitation and reduction commitments inscribed in Annex B to the Protocol).

Protocol to the UNFCCC, 10 December 1997, 16 February 2005, reprinted at 37 ILM 22 (1998).

See the discussion in Lavanya Rajmani in “The Durban Platform For Enhanced Action And The Future Of The Climate Regime” ICLQ Vol 61 / Issue 02 / April 2012, pp 501 — 518.

The Doha Amendment to the Kyoto Protocol was adopted in 2012 and establishes the Kyoto Protocol’s second commitment period (from 2013 until 2020). A total of 144 instruments of acceptance are required for the entry into force of the amendment and 65 countries have so far accepted the amendment, https://unfccc.int/files/kyoto_protocol/application/pdf/kp_doha_amendment_english.pdf, accessed 24 May 2016.

The Cancun Agreements Decision 1/CP.16 which then refers to the need to consider strengthening the long term goal, including in relation to global average temperature rise of 1.5 degrees.

See also Decision 1/CP.17 adopted at Durban in 2011 referring to both 2 degrees and 1.5 degrees; the Communication of the European Commission of 10 January 2007: “Limiting Global Climate Change to 2 degrees Celsius: the way ahead for 2020 and beyond”; the 2011 Communication “A roadmap for moving to a competitive low carbon economy in 2050” and the 2015 Communication “The Paris Protocol-A blueprint for tackling global climate change beyond 2020, which refers to the “below 2 degrees” objective.

IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp. Climate Change 2014: Mitigation of Climate Change. Summary for Policymakers of Working Group III, pp. 10-13.

See CDKN Opinion “COP21 draws to strong end with adoption of 1.5 degree goal” citing Johan Rockström, director of the Stockholm Resilience Institute, warning that a two degree world “contains significant risks for societies everywhere”. Rockström and fellow scientists have called 1.5 degrees “much more scientifically justifiable.”

John Vidal and Fiona Harvey “Paris Climate Talks: Vulnerable countries demand 1.5 degrees warming limit” Guardian London, 30 November 2015 (corrected 1 December 2015), http//www.theguardian.com/global-development/2015/nov/30/paris-climate-talks-vulnerable-countries-demand-15c-warming-limit accessed 9 May 2016.

IPCC, 2014 (n 16) Summary for Policy Makers at page 21.

Climate Change 2014 Mitigation of Climate Change, WG III SPM, SPM4 at page 12.

Referenced in Decision 1/CMP.6 at Cancun.

UNEP Emissions Gap Report 2014, Executive Summary at page xiii.

The UNFCCC COP, by decision 1/CP.20, paragraph 16(b), requested the secretariat to prepare a synthesis report on the aggregate effect of the INDCs communicated by Parties by 1 October 2015. The report contains information compiled and synthesized from 119 INDCs of 147 Parties, representing 75 per cent of Parties and 86 per cent of global emissions in 2010 (see pages 3 and 4 of the report).

See paragraph 4 on page 3 of the Report.

See paragraph 111 onwards.

See paragraph 17 to Decision 1/CP.21.

The first Adaptation Gap Report was produced in 2014.

In 2010, Michel Prieur and Professor Gonzalo Sozzo launched the Non-Regression Knowledge Forum to explore and promote the principle of non-regression, “Non-regression in environmental protection: a new tool for implementing the Rio Principles “Michel Prieur and Geoff Garver, International Centre of Comparative Environmental Law” p2255. For an interesting analysis of the parallels with non-degradation programmes in US environmental law see Robert L. Glicksman, The Justifications for Nondegradation Programs in U.S. Environmental Law in Le principe de nonregréssion en droit de l’environnement (M. Prieur & G. Sozzo, eds. 2012).

European Parliament resolution of 29 September 2011 on developing a common EU position ahead of the United Nations Conference on Sustainable Development (Rio+20) P7_TA(2011)0430 at paragraph 97.

The Parties have invited the IPCC to provide a special report in 2018 on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways (para 21 of COP Decision 1/CP.21.

Article 4(1) of the Paris Agreement.

IPCC, 2014 (n 16), Climate Change 2014 Synthesis Report Summary for Policymakers SPM 2.1 Key Drivers of Future Climate, page 10.

Carbon briefing: Making sense of the IPCC’s new carbon budget, 23 October 2013.

“Breaking the Tragedy of the Horizon — climate change and financial stability”, Speech given by Mark Carney, Governor of the Bank of England Chairman of the Financial Stability Board, 29 September 2015 at Lloyds of London, www.bankofengland.co.uk/publications, accessed 9 May 2016.

Article 4(2).

Article 13.

Article 14.

IPCC, 2014 (n 16), Climate Change 2014 Mitigation of Climate Change, WG III SPM, SPM4 at page 12.

See paragraphs 100-101 of Decision 1/CP.21.

See Paragraph 21 of Decision1/CP.21.

Article 4(4) of the Agreement.

Article 4(5) of the Agreement.

Decision 1/CP.19.

Decision 1/CP.20, para 10.

“Fair Shares: A Civil Society Equity Review of INDCs”, Summary, October 2015, see page 4, www.oxfam.org, accessed 9 May 2016.

Article 4(9).

Article 9(3).

Article 7(14) of the Agreement.

Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, I. C. J. Reports 1996, pp. 241-242, para.29.

Stuart Beck and Elizabeth Burleson (2014). Inside the System, Outside the Box: Palau’s Pursuit of Climate Justice and Security at the United Nations. Transnational Environmental Law, 3, pp17-29 doi:10.1017/S2047102514000028

COP Decision 1/CP.21, para’s 28 and 31.

Article 191(2) (ex Article 174 TEC) of the Treaty on the Functioning of the European Union (TFEU).

Merits, Judgment of 20 April 2010, I.C.J. Reports 2010, p. 3, paragraph 197 of the judgment.

Merits, Judgment of 20 April 2010, I.C.J. Reports 2010, p. 3, paragraphs 101-102 of the judgment.

Rogelj, Schaeffer, Friedlingstein, Gillett, van Vuuren, Riahi, Allen, Knutti “Differences between carbon budget estimates unravelled,” Nature Climate Change, Published Online: 24 February 2016 | DOI: 10.1038/NCLIMATE2868.

Our Common Future, the Brundtland Report 1987

Article 3(1): “… Parties should protect the climate system for the benefit of present and future generations of humankind, on the basis of equity and in accordance with their common but differentiated responsibilities and respective capabilities. Accordingly, the developed country Parties should take the lead in combating climate change and the adverse effects thereof …”

Merits, Judgment of 20 April 2010, I.C.J. Reports 2010, p. 3, paragraph 77.

See for example Article 4 paragraphs (8), (9), (12), (13) and (15), Article 9 paragraphs (1), (5) and (7) and Article 13(4) of the Paris Agreement dealing with NDCs, climate finance and transparency.

Merits, Judgment of 20 April 2010, I.C.J. Reports 2010, p. 3, paragraph 145 of the judgment

Merits, Judgment of 20 April 2010, I.C.J. Reports 2010, p. 3, paragraph 145 of the judgment

Vienna Convention on the Law of Treaties adopted 23 May 1969, entered into force 27 January 1980 UNTS, vol. 1155, p. 331 (VCLT)

See paragraphs 20 and 116.

African Progress Panel “Power, People, Planet: Seizing Africa’s Energy and Climate Opportunities” Africa Progress Report 2015 see page 132, ISBN 978-2-9700821-6-3.

Judgment of the Rechtbank den Haag 24 June 2015 available in English at http://deeplink.rechtspraak.nl/uitspraak?id=ECLI:NL:RBDHA:2015:7196.

Cited at paragraph 2.30 of the judgment (Executive Summary of the UNEP Report).

Para 4.34 of the judgment.

Para 4.31 of the judgment.

See para 4.56 of the judgment

Para 4.56 et seq.

Para 4.70 of the judgment.

Para 4.73 of the judgment.

Paras 4.76-77 of the judgment.

Para 4.86 of the judgment.

Parkerings-Compagniet V Republic of Lithuania, ICSID Arbitration Case No. ARB/05/8, Award 11 September 2007.

Para 333 of the Award, n.77 infra.