1. INTRODUCTION
In contrast to the Kyoto ProtocolFootnote 1 and most other multilateral environmental agreements (MEAs), the Paris Agreement establishes very few substantive legal obligations. For the most part, the Paris Agreement relies on the ‘ambitious efforts’ that parties must ‘undertake and communicate’ as ‘nationally determined contributions [(NDCs)] to the global response to climate change’.Footnote 2 Intended NDCs (INDCs) had been communicated by most parties to the United Nations Framework Convention on Climate Change (UNFCCC)Footnote 3 in advance of the Paris summit. (I)NDCs must cover all main areas of international cooperation as defined in the Paris Agreement, including mitigation, adaptation, financial support, transfer of technology, capacity building, and transparency.Footnote 4 This innovative approach was intended to overcome the opposition of some states to a treaty that had too many substantive provisions. It also successfully navigates the diplomatic complexities of securing negotiated national commitments in a context where there are as many conceptions of differentiation as there are parties to the UNFCCC.
However, international lawyers have divergent views on how (I)NDCs should be characterized. (I)NDCs do not fall squarely within any of the classical sources of international law outlined in the Statute of the International Court of Justice (ICJ) – namely, international conventions, international customs, and general principles of law.Footnote 5 Different views have therefore been expressed regarding the obligations of states under the Paris Agreement in respect of NDCs. This question, however, has typically been dealt with only briefly, as a digression in studies on the legal nature of the Paris Agreement itself.Footnote 6 In recent years this treaty and the continuing negotiations regarding its modalities of implementation have been the primary focus of the literature on international law and climate change. Nevertheless, given that the Paris Agreement itself imposes very few substantive legal obligations, the legal characterization of (I)NDCs is a question of paramount practical importance.
This article identifies and analyzes the international law obligations that arise in relation to (I)NDCs. It argues that such obligations may arise in two distinct ways. On the one hand, treaty obligations arise under the Paris Agreement, inasmuch as it creates an obligation to pursue the mitigation objectives that NDCs define. On the other hand, communications such as (I)NDCs may be among the unilateral declarations that international courts and tribunals have consistently recognized are themselves capable of creating legal obligations. While these two sources of obligation may coincide, they remain distinct. For example, obligations arising under (I)NDCs or similar declarations may apply to states or entities that are not parties to the Paris Agreement, such as Taiwan. (I)NDCs may also define obligations where the Paris Agreement does not – for example, with regard to international support; or they may define obligations of a different nature, such as obligations of result. The potential ‘double-bindingness’ of NDCs could have far-reaching implications more generally for the obligations of states under international law on climate change.
As a prelude to this argument, Section 2 briefly retraces the origins of (I)NDCs. Section 3 analyzes obligations arising from the Paris Agreement in relation to NDCs, and Section 4 turns to the legal force of (I)NDCs and related declarations as unilateral declarations. Section 5 highlights some implications of the double-bindingness of NDCs by comparing the subject, object, nature, and beneficiaries of the respective obligations arising from these two sources. Section 6 concludes.
2. THE ORIGINS OF (INTENDED) NATIONALLY DETERMINED CONTRIBUTIONS
Differentiation has been a central principle from the outset of international negotiations on climate change, but while the parties to the UNFCCC agreed on a ‘principle of common but differentiated responsibilities’,Footnote 7 they disagreed on both the grounds for and the extent of differentiation.Footnote 8 Absent a consensus on the modalities of differentiation, the adoption of an international agreement defining each state’s national commitment on climate change mitigation proved to be particularly challenging.
To overcome this diplomatic quagmire, the Copenhagen Accord of 2009 called on each party to communicate the commitment that it considered to be appropriateFootnote 9 – an approach that the Conference of the Parties (COP) to the UNFCCC formally endorsed in 2010 through the Cancún Agreements.Footnote 10 By the end of 2011, all developed parties had promised quantified economy-wide emissions reduction targets and close to 50 developing states had pledged to implement nationally appropriate mitigation actions.Footnote 11 Taken together, the so-called ‘Cancún Pledges’ were at that time the most ambitious commitment that states had made to reduce greenhouse gas (GHG) emissions and to mitigate climate change. The Cancún Pledges were not entirely successful and failed to hold GHGs in a pathway consistent with the goal of holding global average temperature within two degrees Celsius.Footnote 12 However, the formula proved to be more successful than the late attempt to extend the Kyoto Protocol for a second commitment period.Footnote 13 The Cancún Pledges showcased the relevance of a bottom-up determination of national commitments on climate change mitigation.
In late 2011 COP-17 agreed to launch the Durban Platform for Enhanced Action as ‘a process to develop a protocol, another legal instrument or an agreed outcome with legal force under the Convention applicable to all Parties’.Footnote 14 The instrument (the Paris Agreement) would be adopted at COP-21 in December 2015. This new round of negotiations took full account of the experience of the Cancún Pledges. At COP-19 the parties were formally invited ‘to initiate or intensify domestic preparations for their intended nationally determined contributions’ in the context of adopting this instrument.Footnote 15
Parties were asked to communicate their contribution ‘in a manner that facilitates the clarity, transparency and understanding of the intended contributions’.Footnote 16 It was agreed that the contributions could include:
as appropriate, inter alia, quantifiable information on the reference point … time frames and/or periods for implementation, scope and coverage, planning processes, assumptions and methodological approaches … and how the Party considers that its intended nationally determined contribution is fair and ambitious, in light of its national circumstances, and how it contributes towards achieving the objective of the Convention.Footnote 17
Furthermore, the Lima Call for Climate Action stated that ‘each Party’s [INDC] will represent a progression beyond the current undertaking of that Party’.Footnote 18 These contributions were originally to be oriented towards the ‘ultimate objective’ of the UNFCCC, namely the ‘stabilization of [GHG] concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system’.Footnote 19 As such, INDCs were first and foremost national commitments on climate change mitigation. However, it was soon agreed that parties could also include ‘an adaptation component’ in their INDC.Footnote 20
Almost every state has communicated an INDC, most of them prior to COP-21 and a few of them soon after.Footnote 21 INDCs were published on the UNFCCC website and a synthesis report, prepared by the UNFCCC Secretariat ahead of COP-21, was updated a few months later to incorporate late communications.Footnote 22 INDCs include various national commitments regarding climate change mitigation. Many INDCs address all major sources and sinks of GHG emissions within the country. About half of the INDCs contain quantified emissions reduction targets, which may, for example, be expressed in relation to a base year or a ‘business as usual’ scenario, or as gross domestic product (GDP) or per capita intensity targets.Footnote 23 Other INDCs include quantified targets (for example, regarding the deployment of renewable energy) or simply describe policies and actions.Footnote 24 A large number of INDCs are partly or fully conditional on various other factors and outcomes, such as the results of the Durban Platform for Enhanced Action, efforts carried out by other parties, the availability of flexibility mechanisms, or international support.Footnote 25 More than 80% of INDCs – covering almost every developing state – included an adaptation component which is expressed in various forms – for example, as an assessment of impacts, a statement of goals and visions, a description of measures or actions, or an assessment of the costs and limitations of adaptation.Footnote 26
INDCs vary widely in their form. That of the European Union (EU), for example, is contained in a five-page document, which includes the statement of a ‘binding target of an at least 40% domestic reduction in [GHG] emissions by 2030 compared to 1990’ and clarifications of a mostly methodological nature.Footnote 27 The United States (US) INDC has similar elements and also lists some ‘domestic laws, regulations, and measures’ relevant to its implementation.Footnote 28 By contrast, China submitted a 14-page original document in Chinese, followed by an ‘unofficial translation’.Footnote 29 This document states four main mitigation targets (a peaking of carbon dioxide emissions, a reduction in carbon dioxide intensity, a diversification of energy sources, and an increase in forest stock volume) and details multiple ‘policies and measures’ involving sectoral or sub-sectoral targets.Footnote 30 India’s 38-page communication also includes qualitative objectives (for example, ‘to put forward and further propagate a healthy and sustainable way of living’), in addition to quantitative targets (for example, regarding GHG intensity and electric power installed capacity from non-fossil fuel-based energy resources).Footnote 31
The Paris Agreement centres largely around the implementation of NDCs.Footnote 32 An INDC becomes the party’s NDC when the state becomes a signatory to the Paris Agreement, unless the state decides to communicate a different document.Footnote 33 Article 3 of the Paris Agreement recognizes ‘nationally determined contributions to the global response to climate change’ as efforts to be undertaken with regard to mitigation, adaptation, financial support, transfer of technology, capacity building and transparency.Footnote 34 Yet, it is mostly with regard to mitigation that other provisions of the Paris Agreement refer to NDCs.
In this respect, Article 4.2 contains two essential provisions. Its first sentence establishes a procedural obligation for each party to ‘prepare, communicate and maintain successive [NDCs] that it intends to achieve’.Footnote 35 Other provisions clarify that successive NDCs are to be communicated every five yearsFootnote 36 and will ‘represent a progression’ beyond current NDCs.Footnote 37
Overall, the second sentence of Article 4.2 establishes a substantive obligation for the parties to ‘pursue domestic mitigation measures, with the aim of achieving the objectives of such contribution’.Footnote 38 Relatedly, Article 13 establishes an ‘enhanced transparency framework for action and support’, which seeks in particular to provide ‘clarity and tracking of progress towards achieving Parties’ individual [NDCs] under Article 4’.Footnote 39 As such, parties must regularly provide ‘information necessary to track progress made in implementing and achieving its [NDC] under Article 4’.Footnote 40
3. LEGAL FORCE DERIVED FROM THE PARIS AGREEMENT
This section assesses the international law obligations that arise under the Paris Agreement in relation to its Parties’ NDCs. It first establishes the existence of a substantive obligation under Article 4.2 of the Paris Agreement, then characterizes its nature and object, and assesses its stringency. The section argues that the Parties to the Paris Agreement have an obligation of conduct to pursue measures expected to implement the mitigation target contained in their NDC.
3.1. The Existence of an Obligation
The Paris Agreement is a treaty.Footnote 41 As such, it ‘is binding upon the parties to it and must be performed by them in good faith’.Footnote 42 However, not every treaty provision necessarily creates an obligation. Various provisions of the Paris Agreement appear to define collective aspirations,Footnote 43 recognize the importance of certain efforts,Footnote 44 or encourage parties to adopt a particular course of action.Footnote 45 These provisions do not purport to create any legal obligations, in contrast to other provisions which do seek to establish international law obligations.Footnote 46 These obligations include, most obviously, obligations of a procedural nature,Footnote 47 but they may also include obligations of a substantive nature.
The Paris Agreement seeks to ‘strengthen the global response to the threat of climate change’.Footnote 48 To do this, as with previous international agreements on climate change or MEAs, the Paris Agreement defines collective objectives and seeks to establish national commitments that will achieve these objectives.Footnote 49 However, unlike the Kyoto Protocol and other MEAs,Footnote 50 the parties’ respective targets are neither included within, nor annexed to, the Paris Agreement. Instead, the NDCs communicated by the parties are to be included in a public registry maintained by the UNFCCC Secretariat.Footnote 51 The Paris Agreement calls on all parties, ‘[a]s nationally determined contributions to the global response to climate change … to undertake and communicate ambitious efforts … with the view to achieving the purpose of this Agreement’.Footnote 52 More specifically, the first sentence of Article 4.2 creates a procedural obligation for each party to ‘prepare, communicate and maintain successive [NDCs] that it intends to achieve’.Footnote 53
The fact that the national commitments are not recorded in the body or an annex to the treaty, but instead can be found in a separate registry, says little about the legal force of these commitments. It is not uncommon for a treaty to give legal force to external documents, such as UN Security Council resolutions,Footnote 54 the schedules of concessions under international trade agreements,Footnote 55 and the secondary law of the EU as a whole.Footnote 56 Similarly, the UNFCCC and the Paris Agreement empowered the COP to determine the modalities of treaty obligations relating to national inventories and transparency.Footnote 57 Whether the parties to the Paris Agreement are under an obligation to implement their NDCs depends entirely on the provisions of that treaty. These provisions are to be interpreted within the ordinary meaning of the treaty’s terms, in their context and in light of the treaty’s object and purpose.Footnote 58
The central provision, in this regard, is the second sentence of Article 4.2, which states that ‘Parties shall pursue domestic mitigation measures, with the aim of achieving the objectives of such contributions’. This provision anchors NDCs in the Paris Agreement.Footnote 59 The word ‘shall’, as opposed to ‘should’, indicates an obligation. In the context of a treaty, this obligation is to be interpreted as an international law obligation.Footnote 60
Bodansky contended that this obligation contained in the second sentence of Article 4.2 belongs to ‘parties’ collectively, rather than to each individual party.Footnote 61 However, this contention cannot be reconciled with the terms of the provision and their ordinary meaning. A legal obligation is, by definition, incurred by a legal person. Yet the parties to the Paris Agreement, taken as a group, do not have a legal personality. Therefore, if this provision indicates a collective obligation held by the ‘parties’ as a group, then it cannot be an obligation of a legal nature (although it could be a moral obligation). Such an interpretation would be inconsistent with the word ‘shall’, which, when contained in a treaty, indicates a legal obligation. Therefore, as Winkler notes, the obligation contained in this provision applies to each party individually.Footnote 62 This latter interpretation is confirmed by the fact that other ‘shall’ provisions contained in the Paris Agreement clearly establish legal obligations applicable to each party, including obligations of a procedural nature, even when imposed on ‘parties’ in the plural form.Footnote 63
3.2. The Nature of the Obligation
To understand the nature of the obligation created by the second sentence of Article 4.2 Paris Agreement it is useful to consider the distinction between obligations of result and obligations of conduct. The dichotomy has its origins in Roman law; at present it occupies a central place in the French law of obligations and appears to have influenced the drafting of a text of compromise under the French presidency of COP-21.Footnote 64
Lawyers from the civil law tradition understand an ‘obligation of result’ as the obligation to realize a specified performance.Footnote 65 The performance does not necessarily realize the ultimate purpose of the instrument creating the obligation; it may just represent a step that is likely to promote the ultimate purpose of the instrument. By contrast, an ‘obligation of conduct’ requires an endeavour towards the outcome that has been promised, which may be a specific objective or a general aspiration. A typical example of an obligation of conduct is the obligation of a medical doctor to take measures to cure her patients: she must try, but cannot reasonably be bound to succeed. To conclude that an obligation of result has been breached, a judge needs only to determine that the outcome that had been promised has not been achieved, and that extenuating circumstances do not apply. In contrast, the breach of an obligation of conduct may occur, for example, when a debtor has not acted in a manner that would be expected of a reasonable administrator in the specific circumstances, regardless of the ultimate outcome.Footnote 66
The wording of the second sentence of Article 4.2 means that it cannot be characterized as an obligation of result. Like the medical doctor, state parties are not obliged to achieve a particular outcome; a party would not breach its obligation based only on evidence that the mitigation objective of its NDC has not been realized. Rather, the wording of this provision indicates an obligation of conduct: the parties to the Paris Agreement must ‘pursue measures’ which, they have reasonable grounds to believe, will achieve its object.Footnote 67 ‘Pursue’ should be interpreted as requiring proactive conduct, consistently with other official versions of the Paris AgreementFootnote 68 – the French version (‘prennent des mesures’), for example, implies that the parties are to ‘take’ measures, not just to envisage them.
3.3. The Object of the Obligation
The object of this obligation of conduct is to ‘achiev[e] the objectives’ of successive NDCs.Footnote 69 ‘Objectives’ may be a source of confusion. Some NDCs merely define one or several overall targets,Footnote 70 while others also describe the measures that a party is considering in order to realize these targets.Footnote 71 In the context of the Paris Agreement and in light of its object and purpose, NDCs essentially appear as a national contribution to the ‘global response to the threat of climate change’.Footnote 72 As these ‘objectives’ are to be pursued through ‘mitigation measures’, they do not include targets relating to adaptation, financial support, transfer of technology, capacity building, and transparency. Therefore, the ‘objectives’ of successive NDCs are to be interpreted primarily as the mitigation outcomes described or implied by these successive NDCs.
The specific measures of implementation envisaged in some NDCs do not constitute part of the ‘objective’ of NDCs: they are not part of the object of the obligation arising from the second sentence of Article 4.2. The exclusion of measures of implementation from the object of this obligation is consistent with the ‘principle of sovereignty of States in international cooperation to address climate change’, which suggests that the freedom of states to choose particular mitigation measures should be preserved inasmuch as it does not affect the party’s overall contribution to global efforts.Footnote 73
Bodansky has suggested that the second sentence of Article 4.2 constitutes nothing more than an obligation ‘to pursue [unspecific] measures in good faith’.Footnote 74 This is based on a reading of this sentence as if there were two distinct components – an obligation to pursue domestic measures and an aim to achieve the objectives of NDCs – separated by an impenetrable comma. However, despite the comma,Footnote 75 the sentence suggests that the objectives of NDCs are a benchmark for the stringency of the measures to be pursued.Footnote 76 The French original (‘prennent des mesures internes … en vue de réaliser les objectifs’) indicates more clearly than the convoluted English version that the measures must reasonably be viewed, at the time when they are taken, as capable of realizing the objective.Footnote 77 Therefore, in contrast to the open-ended obligation to ‘implement … programmes containing measures to mitigate climate change’ under the UNFCCC,Footnote 78 the Paris Agreement creates an obligation directed towards a specific objective: the objectives that the parties have defined in their respective NDCs.Footnote 79 The latter obligation of conduct, being more specific, is likely to be significantly more effective than the vague commitment under the UNFCCC.
3.4. Assessment
Commentaries on the Paris Agreement so far have largely seen the obligation of conduct arising from the second sentence of Article 4.2 as less stringent than an obligation of result. Rajamani and Brunnée, for example, note that ‘since Parties do not have an obligation of result in relation to their NDCs, a party could fall short of its NDC without the consequences that attach to breaches of a legal obligation under the law of state responsibility’.Footnote 80 This would be the case, however, only if the party had fallen short of its national commitment on climate change mitigation despite having pursued or taken the measures which could have reasonably been expected of it. This hypothesis is possible but unlikely because the Paris Agreement authorizes the use of internationally transferred mitigation outcomes towards NDCs.Footnote 81 If a state fails to reduce GHG emissions within its own territory, for example, as a result of rapid economic growth, it would probably still be able to ‘buy’ mitigation outcomes from other countries and thus fulfil its own mitigation commitment.
In contrast, a party to the Paris Agreement could breach its obligation of conduct by failing to take relevant measures even if its mitigation commitment had nevertheless been realized.Footnote 82 Furthermore, the breach of an obligation of conduct could be demonstrated well before conclusive evidence regarding the achievement of the mitigation commitment becomes available, thus bridging the gap which allowed Canada to avoid a finding of non-compliance during the commitment period of the Kyoto Protocol.Footnote 83 There is, for example, a strong argument to suggest that the US is currently in breach of its obligation of conduct. The Trump administration has revoked most of the measures which had been taken for the purpose of realizing the US NDC, and no alternative steps have been taken.Footnote 84 This conclusion would remain unaffected if the efforts of non-state actors, or even subnational authorities, were able to achieve the objectives included in the US NDC,Footnote 85 as an obligation of conduct has generally been interpreted as requiring a chain of instructions originating from the competent national authorities.Footnote 86
In summary, the Paris Agreement imposes an obligation on its parties to take adequate measures towards the realization of the mitigation targets contained in their NDCs. This obligation is potentially demanding, depending on the level of ambition contained in each NDC. The obligation, however, is limited to the climate change mitigation targets themselves as opposed to the specific measures envisaged by some NDCs to implement these targets or the targets or measures regarding adaptation to climate change. As this is an obligation of conduct (an obligation to take relevant measures), the responsibility of a party to the Paris Agreement would not automatically be engaged based on the finding that the target was not achieved; but its responsibility could immediately be engaged for failure to take adequate steps towards achieving that target, regardless of whether the target was ultimately achieved.
4. LEGAL FORCE DERIVED FROM A UNILATERAL DECLARATION CAPABLE OF CREATING LEGAL OBLIGATIONS
This section seeks to demonstrate that legal obligations may arise from communications such as (I)NDCs independently of their endorsement in the Paris Agreement.Footnote 87 The first subsection provides a brief overview of the recognition of unilateral declarations as a source of law. The second subsection explores the possibility of characterizing some (I)NDCs and related declarations as instruments capable of creating legal obligations. Finally, the third subsection discusses the conditions, object and nature of the obligations that are most likely to arise from (I)NDCs and related declarations.
4.1. Unilateral Declarations as a Source of Law
Along with treaties, customs and general principles,Footnote 88 unilateral declarations have long been recognized as a source of international law.Footnote 89 In the case regarding the Legal Status of Eastern Greenland, the Permanent Court of International Justice (PCIJ) held that international law obligations had arisen from a reply given by a Minister for Foreign Affairs to the representative of another state.Footnote 90 Similarly, in the Nuclear Tests case the ICJ stated that it is ‘well recognized that declarations made by way of unilateral acts … may have the effect of creating legal obligations’.Footnote 91 According to the ‘principle of good faith’, the ICJ noted that ‘interested States may take cognizance of unilateral declarations and place confidence in them, and are entitled to require that the obligations thus created be respected’.Footnote 92 The ICJ insisted that ‘to have legal effect, there was no need for [unilateral declarations] to be addressed to a particular State, nor was acceptance by any other State required’.Footnote 93 As the ICJ observed in a later case, unilateral declarations are an instrument of choice for states willing to enter into an obligation addressed not just towards one or several other states (as it could do through a treaty), but rather towards the international community as a whole.Footnote 94
The regime of unilateral declarations capable of creating international law obligations was clarified by a study carried out by the International Law Commission (ILC) from 1996 to 2006 and led by Víctor Rodríguez Cedeño. The ‘Guiding Principles Applicable to Unilateral Declarations of States Capable of Creating Legal Obligations’, which the ILC adopted in 2006, considered that unilateral declarations create legal obligations as follows:
∙ the declaration must be made by a competent state agentFootnote 95 and ‘manifest … the will to be bound’,Footnote 96 as evidenced by the content of the declaration, its context and the reactions which followed;Footnote 97
∙ the declaration ‘may be formulated orally or in writing’,Footnote 98 but it must be ‘stated in clear and specific terms’;Footnote 99 and
∙ the declaration may ‘be addressed to the international community as a whole, to one or several States or to other entities’.Footnote 100
4.2. (I)NDCs and Related Declarations as Unilateral Declarations Capable of Creating Legal Obligations
INDCs (for the parties to the UNFCCC not party to the Paris Agreement) and NDCs (upon ratification of the Paris Agreement) appear to meet most of the conditions under which unilateral declarations create international obligations. That (I)NDCs were adopted in the context of a treaty regime (under a decision of the COP to the UNFCCC and then under the Paris Agreement) is no hurdle: the ICJ has routinely recognized unilateral declarations as capable of creating legal obligations in relation to statements recognizing the Court’s jurisdiction under Article 36 of its Statute.Footnote 101 As is required for a unilateral declaration to be capable of creating legal obligations, (I)NDCs are made publicly and, presumably, by the competent national authority.
Similarly, considerable efforts have been made to ensure that INDCs are stated in clear and specific terms. The parties were repeatedly encouraged to communicate their (I)NDCs ‘in a manner that facilitates the clarity, transparency and understanding of the intended contributions’.Footnote 102 In particular, the COP suggested the inclusion of ‘quantifiable information on the reference point …, time frames and/or periods for implementation, scope and coverage, planning processes, assumptions and methodological approaches’.Footnote 103 Such elements would ensure that the achievement of the mitigation objectives of (I)NDCs would be objectively verifiable. A synthesis report by the UNFCCC Secretariat notes that ‘most Parties explicitly addressed the information elements’ which the COP had requested with regard to mitigation action.Footnote 104 Even though many modalities remain to be defined through ongoing negotiations on the Paris Rulebook, the provisions of many (I)NDCs are phrased in terms that are sufficiently clear and specific to express a meaningful commitment. In contrast, the provisions of (I)NDCs with regard to adaptation or support are seldom stated in clear and specific terms.
The critical question is whether (I)NDCs manifest the will of the party to be bound. This question is not necessarily one which allows a one-size-fits-all response. The content of each declaration, its context and the reactions it produced must be taken into account, along with any other relevant circumstances, to determine whether a given (I)NDC is capable of creating legal obligations.Footnote 105 (I)NDCs vary substantially, not only with regard to their wording and content but also as to the context in which they were communicated. In many cases, the objectives of (I)NDCs were announced before their formal communication to the UNFCCC Secretariat, and reiterated subsequently, through a series of oral and written statements by top government officials.Footnote 106 Just like (I)NDCs, these related declarations may create obligations, notwithstanding their form, as long as they are publicly made in clear and specific terms.Footnote 107 Taken as a whole, these repeated statements form a context which may confirm, or possibly exclude, the will of the state to be bound.Footnote 108 While some states may have expressed strong objections to being bound by the contribution they communicated,Footnote 109 others have not.Footnote 110
In general terms, (I)NDCs seem, by their very nature, to involve a will to be bound. (I)NDCs are essentially an attempt to resolve a collective action problem: the parties recognize that every state is better off if all states cooperate to mitigate climate change.Footnote 111 The very reason for a state to communicate its (I)NDC to the UNFCCC Secretariat is to give others confidence that it will seek to implement the commitment on climate change mitigation contained in its (I)NDC, thus encouraging other states to take similar steps. If nothing else, good faith should demand that parties fulfil the promises they made through their (I)NDCs and upon which other parties relied to determine their own conduct.Footnote 112 Such would be most obviously the case when a state receives international support directly or indirectly that is intended to support its mitigation action in response to a conditional mitigation commitment contained in an (I)NDC.
The global context in which the parties to the UNFCCC were invited to communicate their (I)NDCs provide some support for this view. Admittedly, the decisions of the COP to the UNFCCC to call upon parties to communicate their INDCs were ‘without prejudice to the legal nature of the contributions’.Footnote 113 However, this caveat appears to relate to the nature of the obligation (whether it is an obligation of result or an obligation of conduct) rather than to the very existence of an obligation: (I)NDCs were always framed as outcomes that parties intended to pursue or to achieve.Footnote 114 In any case, ‘without prejudice to’ would not exclude the possibility of an individual party expressing an individual will to be bound. (I)NDCs were worded in various terms, with some clearly stating a ‘commit[ment] to a binding target’ (EU),Footnote 115 or an ‘intent[ion] to achieve’ targets (US).Footnote 116
Overall, the context of (I)NDCs includes the text of the Paris Agreement, which was adopted by a consensus of all UNFCCC parties.Footnote 117 Article 4.2 of the Paris Agreement, in its first sentence, calls upon each party to prepare, communicate and maintain the successive NDCs ‘that it intends to achieve’. As Rajamani justly notes, this provision does not create any substantive obligation with regard to achieving the NDCs.Footnote 118 Rather, this provision reflects a common understanding of the nature of (I)NDCs as declarations of what parties intend to achieve.
The ICJ concluded, in the Nuclear Tests case, that an intention to be bound was implied by a public communication of an ‘intention to achieve’ an outcome, particularly given that this communication was made with full knowledge that other states were interested in the outcome. In that case the French government had ‘made public its intention to cease the conduct of atmospheric nuclear tests’,Footnote 119 without explicitly declaring an intention to be bound by this declaration. The ICJ held that, as a result of a statement expressing ‘its intention effectively to terminate these tests’, France ‘was bound to assume that other States might take note of these statements and rely on their being effective’.Footnote 120 The Court concluded that, through a series of unilateral declarations of its ‘intent’, France had undertaken an obligation to cease its nuclear tests.Footnote 121 By analogy, the communication of mitigation outcomes, and the confirmation of an intention to achieve these contributions through the adoption by consensus of the text of the Paris Agreement, strongly suggest a will of the parties to be bound by their (I)NDCs.
Unilateral declarations are generally interpreted restrictively,Footnote 122 as it is not the case that everything said on behalf of a state is meant to create an obligation. However, other factors militate in favour of a broader interpretation of (I)NDCs. Many states recognize, albeit often implicitly, that their (I)NDCs reflect something more than a purely voluntary action, for example, by referring to the party’s ‘international responsibility’Footnote 123 as a basis for determining its action on climate change mitigation. All parties were invited to provide information on ‘how the Party considers that its intended nationally determined contribution is fair and ambitious, in light of its national circumstances, and how it contributes towards achieving the objective of the Convention as set out in its Article 2’.Footnote 124 Many states insist that their commitment represents their fair share of necessary global efforts.Footnote 125
These statements allude to the fact that (I)NDCs do not take place in a legal vacuum: states already have an obligation to prevent activities within their jurisdictions that may cause transboundary damageFootnote 126 and an obligation to mitigate climate change.Footnote 127 (I)NDCs communicate each party’s vision of what they consider to be the fair way of implementing these obligations. Inasmuch as (I)NDCs confirm and implement states’ pre-existing obligations under the UNFCCC and under general international law – in particular, the no-harm principle – they should be subject to a more extensive interpretation.Footnote 128
4.3. Obligations Possibly Arising from (I)NDCs
Just as within a treaty, a distinction needs to be made between those provisions of a unilateral declaration which actually create legal obligations and those provisions which do not. To determine whether a provision creates an obligation, regard must be had to the content of the provision as well as its context. For example, the sections of (I)NDCs that describe national circumstances or recount the steps that a state has already taken do not create any obligations.Footnote 129
In general, it is in relation to mitigation targets that (I)NDCs are most likely to create obligations. Most INDCs contain a clear and specific statement of a mitigation target.Footnote 130 These targets are prepared and communicated for other states to rely on in determining their own conduct. An instrumental consideration leading to a state’s preparation and communication of its (I)NDCs is the contribution that it will make in persuading other states to implement action on climate change mitigation. To paraphrase the ICJ in the Nuclear Tests case, a state communicating a clear and specific mitigation commitment publicly, in whichever form, is ‘bound to assume that other States might take note of these statements and rely on their being effective’.Footnote 131
Other provisions of (I)NDCs are, by nature, less likely to be relied on by other states. In particular, while many (I)NDCs identify and describe the measures envisaged in order to achieve a mitigation target, sometimes in clear and specific terms, these measures appear to be included as a show of good faith and as a way to build confidence in the ability of a state to achieve its target. Whether a state pursues its target through a market-based mechanism, a carbon tax or more traditional command-and-control policies, for instance, does not generally have a direct impact on the interests of third states. Some states have explicitly stated that their INDC could not ‘bind [them] to any sector specific mitigation obligation or action’,Footnote 132 thus confirming that these measures were not intended to create obligations, but also implying that others were.
Likewise, the statement of an objective on climate change adaptation is generally of little relevance to third states, as the success of adaptation action in one country is typically unrelated to adaptation action in other countries. Obligations could conceivably arise where adaptation goals have intended transboundary benefits, for example, with regard to the preservation of a transboundary water body or the protection of transnational ecosystems. Even then the provision would need to be expressed in clear and specific terms in order to reflect an intention to create an obligation. Provisions on adaptation in the (I)NDCs rarely engage with transboundary aspects of adaptation and, even where they do, are usually written in vague and aspirational terms.Footnote 133 Some parties have clearly excluded the possibility that the adaptation component of their INDC could create international law obligations (thus also confirming that other parts of the declaration could create such obligations).Footnote 134
International support is an area where clear and specific provisions could readily be included to create international obligations for high-income countries to promote mitigation action in developing countries. So far, however, potential donor states have been reluctant to include any clear or specific provisions on financial assistance, transfer of technology or capacity building in their (I)NDCs. Some have avoided entirely any mention of support in their INDC (such as the EU and the USFootnote 135 ), while others (such as Japan)Footnote 136 have included only very vague provisions. As NDCs are adjusted and updated, however, political trade-offs could soon result in a clearer commitment by donor states to provide support to developing countries that engage in mitigation action.
Furthermore, obligations may arise from (I)NDCs in relation to the modalities of implementation of climate action, whether related to mitigation, adaptation or support. For example, Macedonia’s INDC contains a clear commitment (‘shall’) to exclude the construction of any nuclear power plant.Footnote 137 Brazil’s INDC expresses the commitment of the Government of Brazil ‘to implementing its INDC with full respect to human rights, in particular rights of vulnerable communities, indigenous populations, traditional communities and workers in sectors affected by relevant policies and plans, while promoting gender-responsive measures’.Footnote 138 While such commitments are unlikely to be invoked in interstate disputes, given that they relate to internal issues, obligations under international human rights law or international environmental law could arguably be raised before domestic jurisdictions.Footnote 139
The obligations that arise from (I)NDCs – most often in relation to mitigation targets – are frequently conditional. For example, Australia pledged a mitigation commitment ‘[u]nder a Paris Agreement applicable to all’.Footnote 140 Even though Australia also stated that its INDC was ‘unconditional’,Footnote 141 it seemingly assumed that no obligation would arise without the adoption of a ‘Paris Agreement applicable to all’. Other INDCs may be deemed to have implied a similar condition based on the context in which they were adopted – the communication of an intended contribution under a forthcoming agreement. Yet, some parties decided to implement their target notwithstanding the adoption of a new agreement. Such is arguably the case of the EU, which started implementing its ‘binding target’ even before the adoption of the Paris Agreement.Footnote 142 Likewise, in the brief period of doubt which followed US President Trump’s decision to withdraw from the Paris Agreement, the Indian government confirmed unequivocally that it would implement the mitigation commitment contained in its NDC with or without the Paris Agreement.Footnote 143 Moreover, the (I)NDCs of some developing countries associate conditions of international support with the realization of their mitigation commitment,Footnote 144 while others include two alternative mitigation commitments, with or without international support.Footnote 145 By contrast, some of the INDCs of developed countries assume that the agreement would allow for the international transfer of mitigation outcomes.Footnote 146
The obligations arising from (I)NDCs also vary with regard to their nature. INDCs were communicated, as noted above, ‘without prejudice to the legal nature of the contributions’,Footnote 147 because of the lack of consensus on whether parties would commit to a form of conduct or to a result.Footnote 148 The obligation contained in the Paris Agreement in relation to the implementation of NDCs is an obligation of conduct.Footnote 149 Yet, some (I)NDCs, including that of the EU, seem to indicate an obligation of result.Footnote 150 Others contrasted an obligation of conduct with an obligation of result: China and the US both committed ‘to achieve’ an outcome (obligation of result) and ‘to make best efforts’ towards a higher outcome (obligation of conduct).Footnote 151 When read in the context of the Paris Agreement, these provisions are qualified by the terms of Article 4.2, second sentence, thus excluding any obligation of result. Yet, inasmuch as these INDCs constitute unilateral declarations capable of creating legal obligations, they also commit these parties to an obligation of result.Footnote 152
5. IMPLICATIONS OF THE ‘DOUBLE-BINDINGNESS’ OF NDCs
The two previous sections identified substantive international law obligations relating to NDCs which arise from two different sources – respectively, the second sentence of Article 4.2 of the Paris Agreement and the NDCs themselves as unilateral declarations capable of creating legal obligations. As these obligations generally call upon states to pursue the same objectives, they are extremely unlikely to conflict.Footnote 153 Therefore, these obligations may coexist. A state or the EU may be bound concurrently by two obligations arising from different sources in connection with the same NDC. These two obligations remain distinct, however, because they have different implications. Obligations arising from the Paris Agreement may exist when no obligation arises from unilateral declarations, or extend beyond the latter, and vice versa. The following section illustrates the implications of the ‘double-bindingness’ of NDCs in four particular respects – namely, with regard to the subject, the object, the nature, and the beneficiaries of the obligations arising from these two sources.
Firstly, obligations arising from different sources may be imposed on different subjects. As a treaty, the Paris Agreement creates obligations applicable to its parties, which are the ‘States and regional economic integration organizations that are Parties to the [UNFCCC]’.Footnote 154 A state cannot be a party to the UNFCCC unless it is a member of the UN or any of its specialized agencies or a party to the Statute of the ICJ.Footnote 155 By contrast, it is largely recognized that ‘any State possesses capacity to undertake obligations through unilateral declarations’.Footnote 156 Beyond states, there appears to be no reason why other entities that can enter into a treaty, such as international organizations or even some subnational entities, would not also be able to undertake international law obligations through unilateral obligations within their domain of competence.Footnote 157
Therefore, states and entities with legal personality under international law could bind themselves by a unilateral declaration analogous to an NDC, even if they are not or could not become party to the UNFCCC. As such, Taiwan – which a few countries recognize as a state and others see as a seditious province of the People’s Republic of China – has communicated an ‘Intended Nationally Determined Contribution’.Footnote 158 In this document, Taiwan announced that it would ‘implement an economy-wide target’ to reduce its GHG emissions by half from a business-as-usual level by 2030.Footnote 159 Other territorial entities have made similar declarations.Footnote 160 This includes self-governing subnational entities, such as the Hong Kong Special Administrative Region, which can enter into international agreements in some domains.Footnote 161 Provided that they are made by an authority vested with the power to do so and express a will to be bound, declarations from these non-state entities could also create international obligations. This may include subnational entities which are not self-governing but which have, in particular circumstances, been recognized as having the competence to conduct international relations.Footnote 162
Secondly, the obligations which arise from the Paris Agreement and from unilateral declarations may have a different object. As noted above, Article 4.2, second sentence, of the Paris Agreement creates an obligation limited to the mitigation objective contained in each NDC. This excludes specific measures of implementation as well as action on adaptation or international support.Footnote 163 On the other hand, unilateral declarations may touch on virtually any conduct, even though a state or entity is more likely to undertake international obligations which are of interest to third parties. Some (I)NDCs and related declarations appear to create obligations with regard to mitigation targets,Footnote 164 while others could soon create obligations to provide financial support, capacity building or transfer of technology, or to cooperate on plans, programmes or policies to address transboundary impacts of climate change. In ongoing negotiations in the coming years, NDCs may be a useful vehicle through which developed states could bind themselves to a commitment to provide predictable international support for climate change mitigation in developing countries in exchange for an increased commitment to climate change mitigation in these countries. Unilateral declarations would have the advantage of bypassing the lengthy and arduous processes associated with the negotiation and adoption of a treaty or its amendment. Politically, it may also be a way for the executive branch to bypass the ratification of a treaty by the legislature.Footnote 165
Thirdly, the obligations that arise from these two sources may differ in nature. Article 4.2, second sentence, of the Paris Agreement creates an obligation of conduct.Footnote 166 By contrast, some unilateral declarations express or, in their context, imply a promise to achieve a target – that is, an obligation of result.Footnote 167 This discrepancy occurs as a result of differences in negotiating positions: while the EU argued for an obligation of result, the US opposed the inclusion in the Paris Agreement of any provision that would require a more stringent ratification process. The compromise involved not only the creation of an obligation of conduct under the Paris Agreement (Article 4.2, second sentence) but also an allusion to an ‘intent[ion] to achieve’ NDCs (Article 4.2, first sentence), thus implying that an obligation of result could arise from these unilateral declarations. Following the adoption of the Paris Agreement, the EU, the US, and China all tacitly confirmed their commitment to the obligation of result, which appears to arise from their INDC by ratifying the Paris Agreement without communicating a different NDC.Footnote 168
Fourthly and finally, the obligations that arise from these two sources are arguably addressed to different beneficiaries. On the one hand, treaties like the Paris Agreement are essentially transactions between states. States make commitments to other parties to the treaty (erga omnes partes), but they do not normally confer rights on third parties.Footnote 169 Treaty provisions expressing an obligation owed to the international community as a whole generally reflect pre-existing obligations under customary international law.Footnote 170 On the other hand, unilateral declarations such as (I)NDCs are not directed towards any particular state. They are made to the international community as a whole (erga omnes), which includes, but is not necessarily limited to, states. Therefore, unilateral declarations can be invoked by states not parties to the relevant treaty. They may also create obligations owed towards non-state actors perhaps more readily than treaties do.Footnote 171 Individuals, groups and societies within a state and abroad have a stronger basis for calling on states to comply with such obligations because they arguably are intended to benefit all.
Beyond these general observations on the subject, object, nature and beneficiaries of obligations, the double-bindingness of NDCs may have other implications that will unfold in concrete cases. For example, the preceding observations regarding the beneficiaries of the obligations may be of particular relevance in the context of domestic litigation. In countries that do not follow an entirely monist tradition, the particular source of an international law obligation may influence its applicability before domestic courts.Footnote 172 A domestic court might recognize the direct applicability of the obligations arising under an NDC or related declarations even when it is not ready to admit the direct applicability of the obligation contained in the second sentence of Article 4.2 of the Paris Agreement.
In addition, the conditions for a party to withdraw from the Paris Agreement may differ from the conditions that apply to revocation of a unilateral declaration.Footnote 173 Absent specific provisions in the declaration, the rule is that a unilateral declaration cannot be revoked in an arbitrary manner.Footnote 174 Courts have generally required notice of withdrawal within ‘a reasonable time’.Footnote 175 Read in the context of general international law – in particular, the no-harm principleFootnote 176 and the emerging notion of non-regressionFootnote 177 – the time-bound mitigation commitments that the party presented as its ‘fair’ share of global efforts should arguably be construed as excluding revocation on any ground short of a fundamental change of circumstances.
Likewise, debates on the possibility of downgrading an NDC should relate not only to the framework provided by the Paris Agreement but also to the conditions for amending or, more likely, revoking a unilateral declaration. While several authors have convincingly argued that the Paris Agreement does not allow parties to downgrade an NDC,Footnote 178 this may not prevent a state from withdrawing from the Paris Agreement and immediately re-acceding to it with a different NDC. However, such indirect downgrading would be prohibited inasmuch as it involves an arbitrary revocation of an NDC.
6. CONCLUSION
Distinct obligations may arise under NDCs in two different ways: either through a treaty provision – namely the second sentence of Article 4.2 of the Paris Agreement – or under NDCs themselves, as unilateral declarations, along with related declarations. Obligations arising from these two sources may coexist without conflicting as they pursue the same objectives, but they do so without merging as they often differ as to their subject, object, nature and beneficiaries. Consideration for the double-bindingness of NDCs should be central to the interpretation of international law obligations on climate change mitigation.
More generally, this analysis highlights a source of international law which, so far, has been given scant attention in the literature on the international law on climate change. The adoption of the Paris Agreement has justly been saluted as a milestone in the development of the field. Yet, the adoption of unilateral declarations by virtually every state, often in a way that strongly suggests a will to be bound by an international obligation, is no less significant an event. Bypassing (temporarily at least) the hurdles of international negotiations and domestic lawmaking, unilateral declarations are an alternative tool through which states may increase their ambition to address climate change mitigation – and be held to achieve it.
Finally, this analysis begs more questions than it answers. To what extent do (I)NDCs and related declarations recognize pre-existing legal obligations (for example, under general international law or under the UNFCCC), rather than create new obligations? What links, if any, exist between the obligations arising from NDCs as unilateral declarations and the diverse mechanisms and institutions established under the UNFCCC regime to foster transparency and compliance? What are the limitations of the constitutional power of the executive branch to make unilateral declarations binding the state beyond the term of a particular government? These and many related questions are beyond the scope of this article and call for further research focused not on the Paris Agreement as a treaty but on the widening array of unilateral declarations capable of creating legal obligations on climate change.
