Several scholars have claimed or implied that the Paris Agreement imposes a collective obligation on states to keep global warming below 2°C, but what is a collective obligation from a legal point of view? The literature that asserts the existence of a collective obligation fails to address this question. In this article I argue two points. Firstly, while a legally binding collective obligation for states is not a theoretical impossibility, the Paris Agreement has not demonstrably created such an obligation; therefore, the collective obligation that appears in the treaty constitutes at most an objective of the Agreement, albeit a crucial one. Secondly, while state observance of the Agreement's apparent collective obligation (but, in fact, paramount objective) is necessary for the success of the treaty, the Agreement does not provide for a process to resolve the global mitigation burden into state-level ambition commitments to ensure that the paramount objective is met. While this is a significant failing of the Agreement, the provisions in the 2018 Paris Rulebook on the global stocktake are sufficiently loose to allow for this mechanism to play a role in the ‘individuation’ of the mitigation burden.
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I am grateful to Benoit Mayer for his comments on an earlier version of this article. No agreement with the views I express here is implied. I am also grateful to the journal's two referees for their constructive criticism in the course of two rounds of comments.
1 New York, NY (US), 9 May 1992, in force 21 Mar. 1994, available at: https://unfccc.int/resource/docs/convkp/conveng.pdf.
2 European Commission, Directorate General for Climate Action (DG CLIMA), ‘Seventh National Communication and Third Biennial Report from the European Union under the UN Framework Convention on Climate Change’, Dec. 2017, pp. ix–x (emphasis added). Earlier occurrences use the same wording: see, e.g., European Commission, ‘Sixth National Communication and First Biennial Report from the European Union under the UN Framework Convention on Climate Change’, 2014 (European Commission, NC6-BR1), p. vii.
3 A ‘conditional offer’ implies an active monitoring of the conditions that would trigger the making of the offer. No such monitoring was taking place.
5 China, ‘Second National Communication on Climate Change of the People's Republic of China’, 2012 (China, NC2), p. 14.
6 This has been noted by some scholars (n. 11 below). Others, however, have claimed that all obligations under the Paris Agreement are procedural, which is not my position, as I will explain below.
7 Kyoto Protocol to the United Nations Framework Convention on Climate Change (Kyoto Protocol), Kyoto (Japan), 11 Dec. 1997, in force 16 Feb. 2005, available at: http://unfccc.int/resource/docs/convkp/kpeng.pdf.
8 Art. 13(3)–(4), Paris Agreement.
9 Consider, by way of contrast, the statement that biodiversity loss is a common concern of humankind. This is a different kind of statement than the one about climate change. Biodiversity loss is divisible into the sum of local losses. Climate change is not divisible into local changes; rather, it is the consequence of the changing composition of the Earth's atmosphere. The changed atmosphere is a single and indivisible object. The preambular statement's affirmation in the Paris Agreement of a ‘common concern’ thus concerns an unprecedented kind of anthropogenic environmental interference.
10 This link is repeated in Decision 1/CP.21, ‘Adoption of the Paris Agreement’ (13 Dec. 2015), UN Doc. FCCC/CP/2015/10/Add.1, para. 13 (‘[A]ll Parties [are] to communicate to the secretariat their intended nationally determined contributions towards achieving the objective of the Convention as set out in its Article 2’).
11 Voigt , C. , ‘ The Compliance and Implementation Mechanism of the Paris Agreement ’ ( 2016 ) 25 ( 2 ) Review of European, Comparative, and International Environmental Law , pp. 161 –73CrossRefGoogle Scholar , at 161 (‘[the Paris Agreement] establish[ed] mainly administrative, procedural obligations of a legally binding nature, leaving the substantive content to a large extent to the discretion of parties’); and 166 (‘[the] legally binding obligations for all parties … are of a procedural nature only, while the substance of mitigation, adaptation and finance obligations is not legally binding and left to the sovereign discretion of parties’); S. Oberthür & R. Bodle, ‘Legal Form and Nature of the Paris Outcome’ (2016) 6(1–2) Climate Law, pp. 40–57, at 40, 56 (‘The Paris Agreement is an international treaty focused on establishing procedural obligations’); Rajamani , L. , ‘ Ambition and Differentiation in the 2015 Paris Agreement: Interpretative Possibilities and Underlying Politics ’ ( 2016 ) 65 ( 2 ) International and Comparative Law Quarterly , pp. 493 – 514 , at 493CrossRefGoogle Scholar (‘The Paris Agreement contains aspirational goals, binding obligations of conduct in relation to mitigation’); Rajamani , L. & Brunnée , J. , ‘ The Legality of Downgrading Nationally Determined Contributions under the Paris Agreement: Lessons from the US Disengagement ’ ( 2017 ) 29 ( 3 ) Journal of Environmental Law , pp. 537 –51, at 542CrossRefGoogle Scholar (‘Parties do not have binding obligations of result in relation to their NDCs’, and ‘The Paris Agreement deferred to [those states who did not wish to subject themselves to legally binding obligations of result], but enshrined binding obligations of conduct for Parties, coupled with a good faith expectation of results’); Huggins , A. , ‘ The Evolution of Differential Treatment in International Climate Law: Innovation, Experimentation, and “Hot’ Law” ’ ( 2018 ) 8 ( 3 –4) Climate Law , pp. 195 – 206 , at 196CrossRefGoogle Scholar (‘[the regime's] legal frameworks have evolved from relatively vague provisions in the UNFCCC, to binding targets for industrialized countries under the Kyoto Protocol, to obligations of conduct (but not result) under the Paris Agreement’); and Mayer , B. , ‘ Obligations of Conduct in the International Law on Climate Change: A Defence ’ ( 2018 ) 27 ( 2 ) Review of European, Comparative, and International Environmental Law , pp. 130 –40, at 132CrossRefGoogle Scholar (‘[while] the UNFCCC established an open-ended obligation of conduct, the Kyoto Protocol, by contrast, created an obligation of result. In turn, the Paris Agreement reverted to an obligation of conduct’).
12 The Paris Agreement's collective obligation is not the same as that of the objective of Art. 3(1) of the Kyoto Protocol of ‘reducing [Annex I party] overall emissions of such gases [listed in Annex A] by at least 5% below 1990 levels in the commitment period 2008 to 2012’. The figure of 5% was to be an aggregate of the mitigation actions of Annex I parties and had no other significance beyond that. Compared with the Paris Agreement's below 2°C requirement, which adds specificity to Art. 2 of the UNFCCC, the Kyoto Protocol's 5% reduction target is an entirely different legal construct. It is a means to an end – the means being the actions of a minority of parties over a period of 5 years – in contrast with the Paris Agreement's 2°C containment outcome, which is an end in itself for all parties. As for the UNFCCC, its wholly vague objective in Art. 2 is not a substantive legal obligation, whether collective or otherwise.
13 See, e.g., Raupach , M.R. et al. , ‘ Sharing a Quota on Cumulative Carbon Emissions ’ ( 2014 ) 4 ( 10 ) Nature Climate Change , pp. 873 –9CrossRefGoogle Scholar ; Anderson , K. & Peters , G. , ‘ The Trouble with Negative Emissions ’ ( 2016 ) 354 ( 6309 ) Science , pp. 182 –3CrossRefGoogle ScholarPubMed ; Rogelj , J. et al. , ‘ Differences between Carbon Budget Estimates Unravelled ’ ( 2016 ) 6 ( 3 ) Nature Climate Change , pp. 245 –52CrossRefGoogle Scholar ; Schleussner , C.-F. et al. , ‘ Science and Policy Characteristics of the Paris Agreement Temperature Goal ’ ( 2016 ) 6 ( 9 ) Nature Climate Change , pp. 827 –35CrossRefGoogle Scholar ; Peters , G.P. et al. , ‘ Key Indicators to Track Current Progress and Future Ambition of the Paris Agreement ’ ( 2017 ) 7 ( 2 ) Nature Climate Change , pp. 118 –22, at 121CrossRefGoogle Scholar ; and Carbon Pricing Leadership Coalition and World Bank Group, ‘Report of the High-Level Commission on Carbon Prices’, 29 May 2017, p. 6, available at: https://www.carbonpricingleadership.org/report-of-the-highlevel-commission-on-carbon-prices.
14 Decision 1/CP.21, n. 10 above, para. 52 (emphasis added).
15 Rajamani , L. , ‘ The 2015 Paris Agreement: Interplay between Hard, Soft and Non-Obligations ’ ( 2016 ) 28 ( 2 ) Journal of Environmental Law , pp. 337 –58, at 343CrossRefGoogle Scholar (‘It matters to whom the provision is addressed or who it identifies as actors. If the provision is addressed to “each Party”, it denotes an individual obligation. If it is addressed to “all Parties”, it could denote a collective obligation. If it refers to “Parties”, in some cases, depending on the context, it could be a cooperative or collective obligation; in others, it could be a blanket or universal reference to “Parties”, not necessarily signalling a collective or cooperative obligation’); and at 352 (where Rajamani recognizes a category of individual ‘hard’ obligations, which ‘lend themselves to assessments of compliance/non-compliance’, and appears to imply that collective ‘hard’ obligations also exist); Rajamani, n. 11 above, pp. 497, 501, 503 (where she distinguishes between collective and individual obligations; contrasts collective and individual ‘requirements’ and collective and individual ‘expectations’); C. Voigt, ‘The Paris Agreement: What Is the Standard of Conduct for Parties?’, Questions of International Law online articles, 24 Mar. 2016, pp. 17–28, at 17, available at: http://www.qil-qdi.org/paris-agreement-standard-conduct-parties (‘Some [treaty provisions] contain legally binding obligations, either of [a] substantive or of [a] procedural nature. Such obligations can be collective or individual’); Bodansky , D. , ‘ The Legal Character of the Paris Agreement ’ ( 2016 ) 25 ( 2 ) Review of European, Comparative, and International Environmental Law , pp. 142 –50, at 145–7CrossRefGoogle Scholar (where he categorizes obligations as collective or individual: e.g. ‘provisions … intended to create collective rather than individual obligations’, and uses ‘collective aim’ differently from ‘collective obligation’); Bodansky , D. , Brunnée , J. & Rajamani , L. , International Climate Change Law ( Oxford University Press , 2017 ), pp. 18 , 218–9, 225, 231, 234–5, 243Google Scholar (where they categorize obligations as collective or individual, and distinguish between collective and individual ‘expectations’ and between collective obligations and ‘goals’); Peel , J. , ‘ Climate Change ’, in Nollkaemper , A. & Plakokefalos , I. (eds), The Practice of Shared Responsibility in International Law ( Cambridge University Press , 2017 ), pp. 1009 –50, at 1024CrossRefGoogle Scholar (where reference is made to the UNFCCC, not the Paris Agreement: ‘At their highest, these provisions [in Art. 3 UNFCCC] might give rise to a collective obligation on the part of Convention parties to stabilise emissions at a level adequate to protect the climate system now and in the future, and to avoid dangerous anthropogenic warming’); Rajamani & Brunnée, n. 11 above, pp. 541, 543 (where the authors identify ‘individual obligations’ as well as ‘collective responsibility language’, thus implying that collective obligations also exist); Huggins, n. 11 above, p. 204 (‘the Paris Agreement imposes a collective obligation on all parties to hold 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’); Voigt , C. & Ferreira , F. , ‘ Differentiation in the Paris Agreement ’ ( 2016 ) 6 ( 1 –2) Climate Law , pp. 58 – 74 , at 69–70CrossRefGoogle Scholar (referring to ‘collective legally binding commitments’ in relation to climate finance and implying the existence of collective obligations by qualifying some obligations as ‘individual’). Note also Peel's claim that the Kyoto Protocol's 5% reduction target for Annex I Parties for the first commitment period was a ‘soft collective obligation’: Peel, ibid., p. 1026.
16 Works that neither mention a collective obligation nor imply its existence through a contrast with ‘individual’ obligations include Bodansky , D. , ‘ The Paris Climate Change Agreement: A New Hope? ’ ( 2016 ) 110 ( 2 ) American Journal of International Law , pp. 288 – 319 CrossRefGoogle Scholar ; Doelle , M. , ‘ The Paris Agreement: Historic Breakthrough or High Stakes Experiment? ’ ( 2016 ) 6 ( 1 –2) Climate Law , pp. 1 – 20 , at 4, 8–9CrossRefGoogle Scholar (referring only to collective ‘goal’ and collective ‘mitigation effort’); Lawrence , P. & Wong , D. , ‘ Soft Law in the Paris Climate Agreement: Strength or Weakness? ’ ( 2017 ) 26 ( 3 ) Review of European, Comparative, and International Environmental Law , pp. 276 –86, at 279, 281CrossRefGoogle Scholar (collective ‘goal’ and collective ‘non-binding objective’ only); Oberthür & Bodle, n. 11 above; H. van Asselt, ‘International Climate Change Law in a Bottom-up World’, Questions of International Law online articles, 24 Mar. 2016, pp. 5–15, available at: http://www.qil-qdi.org/international-climate-change-law-bottom-world; Voigt, n. 11 above; Mayer, n. 11 above; Mayer , B. , The International Law on Climate Change ( Cambridge University Press , 2018 ), pp. 17 , 72, 87, 111, 201, 214, 218Google Scholar (where he mentions collective ‘attempt’, ‘determination’, ‘ambition’, ‘objectives’, ‘commitment’, ‘mobilization goals’, and ‘target’, but not collective obligation).
17 See the works by Bodansky and Voigt cited at nn 15 and 16 above.