Ambition as a Legal Concept in the Paris Agreement and Climate Litigation: Some Reflections

1 Introduction

The Framework Convention on Climate Change (FCCC) and the Paris Agreement (PA) are the essential contractual sources of international climate law. The FCCC contains formally binding substantive and procedural obligations on mitigation and adaptation the prescriptiveness of which, however, is strongly reduced by the lack of precision of their content. The Paris Agreement also is a formally binding international agreement. Even more than the Framework Convention, it has a hybrid structure of prescriptive and aspirational norms, precision and vagueness of content and substantive and procedural requirements. The agreement uses a multitude of different, finely nuanced wordings to describe the commitments of Parties that make it difficult to draw a clear borderline between prescriptive norms, aspirational norms and mere factual statements and between hard law and soft law. In legal literature, the classification ranges from binding rules to duties of care to soft law to more or less strong normative expectations. 1 The prescriptive cornerstone of the Paris Agreement is the now generally accepted goal to avoid global warming by keeping average temperature well below 2 degrees Celsius above the pre-industrial level and pursue efforts to limit global warming to 1.5 degrees Celsius (Article 2(1) PA). Taking into account the already existing stocks of greenhouse gases in the atmosphere, a global rest budget of carbon that can be emitted without missing these goals can be derived. 2 According to the Agreement’s new allocation, this is to be allocated to state Parties through pledges on national emissions reduction targets.

“Ambition” is a key concept of the Agreement to achieve the temperature goals. Even though its legal content is controversial, it is a yardstick for implementing the Agreement; it dominates the substantive requirements on mitigation and adaptation and serves as guidance for fulfilling the procedural obligations set out by the Agreement. In contrast, ambition is at best implicit in the general obligations under the FCCC on updating emission reduction programs (Article 4(1)(b) and the specific provisions on emissions reduction policies and measures programs of developed countries (Article 4(2)(a) and (b) FCCC). Thus, the expectation that the policies and measures of developed countries “will demonstrate that [they”] are taking the lead” in returning to 1990 emission levels by 2000 and the motivation of the respective information obligations to the extent that these countries individually aim “to promote progress” in this regard (which are now moot) can be understood as an expression of ambition. 3

The article discusses the meaning and content of “ambition” as a legal concept of international climate law, especially with respect to mitigation under the Paris Agreement. As there is as yet no relevant international case law and progress in mitigation under the umbrella of the Paris Agreement has been far from being satisfactory, the article lays particular emphasis on the contribution national court decisions can make to the understanding and application of the ambition concept in the framework of national policy and law designed to implement the Paris Agreement.

Ambition under the UNFCCC will only be addressed where this convention contains additional requirements. In the negotiations on the Paris Agreement, its relationship to the FCCC was controversial between developing and developed countries. This controversy has been solved by a compromise text contained in the chapeau of Article 2(1) PA. According to this provision, the Paris Agreement by enhancing the implementation of the FCCC, including its objective, aims to strengthen the global response to the threat of climate change. There is common agreement that the Paris Agreement is an ancillary agreement that does not dismantle but rather builds on the FCCC. It concretises and supplements the FCCC. 4 Under the Vienna Convention on the Law of Treaties there are no specific rules regarding the rank of a later treaty that concretises and supplements an earlier one. However, Article 30(3) of the Convention is in principle also applicable to supplementary treaties. 5 Since in most cases such treaties only are different but not incompatible with the earlier treaty, there is not normally any ranking problem and hence no justification for the application of the “lex posterior” rule. 6 As regards the mitigation obligations and commitments under the two treaties, compliance with the FCCC, especially its Article 3(3), certainly is not sufficient to meet the requirements of the Paris Agreement but does not impair the implementation of the latter agreement. However, since the Paris Agreement establishes more concrete and more stringent, partly also more extensive requirements, it at least practically supersedes the FCCC which is reduced to a mere gap filling function.

2 Summary of the provisions of the Paris Agreement on ambition

3 Recent developments

Although progress in implementing the Paris Agreement has been slow and much time has been spent to take the requisite decisions on specifying the procedures provided for in the Agreement, one can state that with the outcomes of the Katowice and Glasgow climate conferences most of the “formal” work is done by now. The Glasgow Climate Conference has also generated some substantive outcomes. These are, in particular, the new target of a reduction of 45 percent of the emissions in 2010 by the year 2030, a statement on the importance of the 1.5 degrees goal and the urgency of upgrading ambition and accelerated action for meeting it, the inclusion of an important non-carbon greenhouse gas, an integrated view of climate protection and the conservation and restoration of biodiversity 13 and last but not least the objectives of phasing down unabated coal power and phasing out inefficient fossil fuel subsidies, 14 even though the two latter objectives could be more ambitious.

4 Perspectives on the content of the ambition concept

The Paris Agreement basically relies on incentives for voluntary emissions reduction based on self-assessment by the Party states and the catalyst effect of transparency and procedure. However, self-assessment is bounded by substantive requirements of unclear prescriptiveness. Major elements are the requirements of “ambition”, “highest possible ambition” and “progression”. Most commentators classify these requirements as mere normative expectations, 15 others see in them duties of care, at least with respect to “highest possible ambition” as laid down in Article 4(3) PA. 16 In any case, the pursuance of highest possible ambition in the NDCs does not exclusively rest on free self-judgement by the state Parties. Rather, ambition arguably is an objective yardstick for assessing and justifying the quality of NDCs in the facilitative multilateral discussion among the parties under Article 13(11) PA and the stocktaking under Article 14(1) and (3) PA. 17 The NDCs are open to comments and criticism for lack of sufficient ambition.

However, the problem is that the Agreement does not contain any definition of ambition and progression and there is a lack of clear ideas about the meaning of these notions, especially of “highest possible ambition”. As regards mitigation, arguably a contribution to emissions reduction that is not merely insignificant must be made to deserve a classification as “ambitious”. Progression is equivalent to increased ambition, while the notion of highest possible ambition contains a value judgment as to the strength of efforts pursued by the relevant state. Ambition and progression can consist in a transition from soft law to binding rules, from emissions reductions in particular sectors to economy-wide reductions, from carbon-intensity to absolute carbon reductions. 18 According to the Agreement, the emphasis is to be laid on absolute emissions reductions rather than a mere improvement of carbon efficiency (Article 4(4) PA). Developing country Parties possess much more leeway, but are encouraged to engage in a transition towards absolute emissions reductions or limitations. However, what counts, is the amount of emissions reductions. This must be assessed in the light of the goals of the Paris Agreement which in turn are based on scientific assumptions about the need for emissions reductions in absolute, quantitative terms before reaching climate neutrality in 2050. Since accumulation of greenhouse gases is the major cause of global warming, the reduction path over time by 2050 also needs to be included. Accelerated action is addressed in the Paris Agreement only with respect to peaking (Article 4(1) PA), but has been generalized by an implementing decision of the Glasgow Climate Conference. 19 According to best available climate science, if one wants to achieve the 1.5 degrees C goal an emissions reduction of at least 45 percent by 2030 before reaching climate neutrality in 2050 is required. 20 The remaining global budget of accumulated emissions needs to be translated into national targets (budgets) which may be lower or may be higher than 45 percent.

Major guidance for interpreting the notion of requisite ambition and allocating the remaining budget is provided by the principle of common but differentiated responsibilities and respective capabilities in the light of different national circumstances (CBDR principle) as well as by considerations of equity. 21 Moreover, the precautionary principle and the principle of sustainable development set out by Article 3(3) and (4) FCCC are relevant. The CBDR principle as embodied in the Paris Agreement constitutes an evolution from the former, mostly binary CBDR principles (developed vs. developing countries) 22 to a more flexible and dynamic concept. Some scholars 23 even recognize it as an entirely new distributional principle. The modified CBDR principle is explicitly referred to in Article 2(2) PA and besides in Article 4(3) and (19) PA. However, the distinction between developed and developing countries has not been entirely abolished but survives in several other provisions of the Agreement, even though without a classification by country lists and, as regards the requisite actions, in a more flexible and dynamic form. According to Article 4(4) PA the developed country Parties should continue taking the lead in reducing greenhouse gas emissions and they are the major source of financing and technology transfer under other provisions of the Agreement. Developing country Parties should continue enhancing their mitigation efforts (see also Article 3, second sentence on NDCs).

The new formula of the CBDR principle embodies responsibility, problem-solving capability and social and economic national circumstances. In addition, equity considerations are relevant. All this raises problems of interpretation, but also of weighting and balancing the different elements of the new formula. In principle, the CBDR principle is open to self-differencing. 24 This means that the state Parties to the Agreement may, and realistically speaking will, sustain different positions as to particular issues in response to their interests. However, there are boundaries in the shape of normative expectations or even duties of care which can be invoked by other state Parties in the facilitative multilateral discussion under Article 13(11) PA and the periodic stocktaking under Article 14 (1) and (3) PA. 25

Responsibility reflects the contribution of a country to the problem (Rio Principle Article 7). However, the long history of discussion on the CBDR principle shows that there is no agreement on the constituent elements and modulations of responsibility. Especially the issue of historical responsibility for the existing concentration of greenhouse gases in the atmosphere (stocks) –as opposed to current emissions (flows) –has remained controversial. 26 Apart from this, there has been no agreement on the criteria for determining the extent of (present and historical) responsibility. Consequently, depending on their interests, the states will either assert or reject particular allocation criteria. The polluter pays principle is too abstract to provide guidance for determining responsibility for climate damage.

Capability is easier to grasp and apply. Financial, technological and human capacity, the national GDP, carbon efficiency, reduction costs and opportunity costs will enter into the account of capability. 27 These factors provide arguments that may become relevant in taking a decision on a particular degree of ambition, considering the major national measures envisaged for devising and implementing the NDCs and their economic and social consequences. Especially in the context of “highest possible ambition” the abstract possibility of emission reduction needs to be qualified in order to avoid excessive burdens. Relevant criteria could be practical possibility, reasonableness, proportionality and conformity with the constitutional protection of justified expectations.

National circumstances is a fall-back criterion for considering other elements of relevance that may justify a lesser degree of ambition or suggest a higher degree of ambition to be pursued by a particular state. One can mention the state of development, the institutional structure, the economic, transport and energy structure, social problems, geographical and climate profiles and vulnerability to climate change.

It appears reasonable to assume that the three elements of requisite or expected ambition and progression need to be balanced with one another, considering proportionality. However, balancing is a complex process. As there are no recognized rules on how to weight the three criteria, the state Parties may weight them differently and balance them with one another differently and all this in changing combinations. Moreover, equity considerations allow for a correction and flexible assessment of the results generated by application of these three elements of ambition. Equity may include fairness, justice, intergenerational equality, the right to development, poverty eradication, redistribution and restoration. 28 Equity considerations may lead to further differentiation, the more so since equity concepts vary between countries.

An expression of the reformulated CBDR principle including equity is the postulate of a “fair share” in the global rest emissions budget, that is, a fair remaining national emissions budget. 29 The Paris Agreement has abstained from including any language about the expected concrete shares of state Parties in efforts to reduce emissions. This issue has as yet solely been the subject of academic discussion and to certain extent court decisions. As from the 1990 s, there have been dozens of proposals for allocation rules by legal scholars, economists or political scientists. The population size (emissions per capita), size of the economy (emissions per GDP), geographic size of the country (emissions per square kilometre) or ecological footprint are among the factors proposed. Besides using a single factor, also a number of composite factors based on varying “mixture rules” have been discussed. 30 It is evident that these criteria would render quite different results as to what one accepts to be a “fair share” of the remaining global emissions budget. Based on the Paris Agreement’s concept of self-differentiation, state Parties have a major degree of allocation discretion, so that one could at best make the negative statement that particular factors are not appropriate and need to be discarded or at least be given a low weight.

Against this backdrop, it appears overoptimistic to believe that the new CBDR principle will work as a catalyst for a race of the state Parties to the top of climate protection. 31 What can be concluded with more certainty is that the CBDR principle may raise the justification burden for a lack of ambition of the respective NDCs and their implementation and that it may also promote political ambition alliances at international level.

All told, based on experience gained so far, there are considerable difficulties in identifying a generally accepted, uniform interpretation of ambition in the Paris Agreement. Since the ambition test does not only pertain to the mere choice of the quantity and timing of national emissions reductions, but also –and even more –the selection of measures of implementation and the conflicts that may be caused by particular measures, national practice is of particular importance. From the perspective of the international climate regime, the process, that is, the transparency, joint discussion and global stocktake of the NDCs and their expected improvement over time are at the centre of attention. In a legal perspective, it makes sense to also look for guidance by the national judiciary that has dealt with, or has otherwise been relevant to, the application of the ambition requirement “on the ground.”

5 Inspirations for the interpretation of “ambition” by national court decisions

6 Conclusion

To sum up, the national decisions that deal with “ambition” of climate protection address some constitutive elements of this concept, even though they proceed in a rather selective way and focus on different aspects of ambition. The term “ambition” is rarely explicitly referred to. Implicit arguments regarding ambition prevail. Some decisions are based on human rights which offer the chance of achieving a higher degree of ambition, while the majority simply apply domestic statutory law. The relevant elements of ambition referred to with respect to target-setting, especially with relevance to the NDCs, are climate science and the concept of a global rest emissions budget as posited by the various IPCC reports, the need to take the Paris Agreement into account, a fair or just national share in reducing global greenhouse gas emissions and/or the concept of a fair national rest emissions budget, international cooperation, the duty to take care including precaution and intergenerational justice and the need for a long-term planning trajectory for emissions reduction. With respect to measures of implementation, the power of national legislatures and governments to balance climate protection with conflicting concerns, taking due account of the future climate risks for younger and future generations, is emphasized. In the balancing process, the principle of proportionality plays a major role. Measures that are unsuited or impossible to take or impose disproportionate burdens on the addressees are not permissible. As target-setting to a major degree also depends on the feasibility of particular measures and the solution of conflicts arising at the level of implementation, a generous grant of implementation discretion also has major repercussions on target-setting.

In any case, the decisions do not shed sufficient light on concrete questions of application “on the ground” so that crucial issues remain open. For instance, they do not or at best only summarily discuss the concrete meaning of a “fair share”. They do not inform the government about which factual circumstances could justify to assume impossibility and/or disproportionality of concrete implementation measures. The decisions are valuable as they may enrich the deliberations on the concept of ambition and encourage more ambitious national action and litigation on mitigation, including through transnational learning. However, they are mostly not specific enough to draw robust conclusions from them. This also means that their power in the international negotiation process on the further implementation of the Paris Agreement is bound to remain limited. Apart from their contribution to the understanding of the notion of “ambition”, some decisions also raise serious questions of the constitutional division of competences between parliament, the government and the judiciary which, however, depend on the respective constitutional order and are not amenable to generalisation.