The Paris Agreement turns 10 in the middle of a critical decade

In the decade since the adoption of the Paris Agreement in December 2015, international relations have changed beyond recognition. It would be tempting to see such change as a mere epiphenomenon, belonging to what Fernand Braudel famously dismissed, borrowing François Simiand’s terminology, as mere changes in the short-term history of ‘events’ (histoire événementielle), to contrast it with the deeper processes unfolding in the ‘longue durée’. ¹ Yet, two fundamental differences should serve as warning. First, the Paris Agreement was adopted to confront something genuinely new under the Sun, to borrow the title of John McNeill’s environmental history of the XX Century. ² Humanity, or more accurately certain parts of it, ³ have become a force of geological proportions affecting the dynamics of the climate and, more generally, the Earth system. ⁴ This is new at any human timescale, even beyond those that separate human ‘history’ and ‘pre-history’. Second, the ‘events’ of this critical decade 2020-2030 ⁵ will loom large on the deep future, as they may trigger and lock-in processes defining the very environmental conditions within which future generations will live and struggle for thousands of years.

As lawyers, our role is to organise the collective efforts to rise to this ‘unprecedented challenge of civilisational proportions’ ⁶ , and a key milestone in such efforts was the adoption of the Paris Agreement. As former COP21 President and co-editor of this special issue Laurent Fabius knows all too well, the text of the Paris Agreement is the expression of many complex compromises, often papered over in ambiguous formulations. But the esprit de Paris was and remains clear. In his own words ‘better, faster, together’. In a recent advisory opinion, the International Court of Justice, acting unanimously, breathed new life into this understanding of the Paris Agreement. It emphasised, in the clearest terms, that the Paris Agreement sets ‘stringent’ obligations of due diligence, in particular in relation to mitigation. ⁷

As I write these introductory lines for our special issue, it has become inescapable that this spirit of Paris needs to find expression not only in the negotiations of COP30 in Belém, but also in international and domestic climate litigation, financial decision-making, global governance processes on issues as diverse as human rights, health, trade, investment and even international security, and of course also in domestic policies. There are significant synergies between achieving reductions of emissions of greenhouse gases and economic performance. To take two examples, in 2024, the ‘net zero’ sectors grew three times as fast as the wider economy in countries such as the UK ⁸ or China. ⁹ Much of this growth can be explained by purposive and deliberate policies, enshrined in law, in support of specific technologies. ¹⁰

Law permeates and structures the organisation of society. It is only one part of such organisation. As the International Court of Justice observed in the closing paragraph of its recent advisory opinion on climate change: ‘the questions posed by the General Assembly represent more than a legal problem: they concern an existential problem of planetary proportions that imperils all forms of life and the very health of our planet. International law, whose authority has been invoked by the General Assembly, has an important but ultimately limited role in resolving this problem. A complete solution to this daunting, and self-inflicted, problem requires the contribution of all fields of human knowledge, whether law, science, economics or any other’. ¹¹ But law is an important part, because it sets the overall bounds within which socio-economic processes unfold.

From this wider perspective, it appeared timely to devote a special issue of RED to the 10^th anniversary of the adoption of the Paris Agreement, and to situate it in the current critical decade 2020-2030, where much of humanity’s future is at stake. The contributions to this issue represent different viewpoints. In some cases, they give expression to how key decision-makers, political or otherwise, see the challenge and their role in it. In other cases, they clarify the legal and institutional architecture in which the struggle between stability and change unfolds. In yet other cases, they provide perspectives from beyond law to shed light on the scientific and economic fundamentals constraining the choices to be made. In all cases, they provide actionable insights on what the esprit de Paris is and what it could achieve in this critical decade.

1. F. Braudel, ‘Histoire et sciences sociales : La longue durée’ (1958) 13(4) Annales. Économies, Sociétés, Civilisations 725
2. J. R. McNeill, Something New Under the Sun: An Environmental History of the Twentieth-Century World (2000). See W. Steffen, W. Broadgate, L. Deutsch, O. Gaffney, C. Ludwig, ‘The trajectory of the Anthropocene: The great acceleration’ (2015) 2 The Anthropocene Review 81.
3. J. E. Viñuales, The Organisation of the Anthropocene – In Our Hands? (The Hague, Brill, 2018), at 32-56
4. K. Richardson et al, ‘Earth beyond six of nine planetary boundaries’ (2023) 9/37 Science Advances eadh2458
5. O. Hailes, J. E. Viñuales, ‘The energy transition at a critical juncture’ (2023) 26 Journal of International Economic Law 627
6. UN General Assembly Resolution 77/276: ‘Request for an advisory opinion of the International Court of Justice on the obligations of States in respect of climate change’, 29 March 2023 (adopted by consensus), A/RES/77/276, preambular paragraph 1.
7. Obligations of States in respect of climate change, Advisory Opinion (23 July 2025), ICJ General List No. 187, para. 246.
8. Confederation of British Industry (CBI) Economics, The Future is Green. The Economic Opportunities brought by the UK’s Net Zero Economy (February 2025), Executive Summary
9. Ember, China Energy Transition Review (9 September 2025), Executive Summary.
10. EEIST Consortium, Economics of Energy Innovation and System Transition: Synthesis Report (2024), Executive Summary
11. Obligations of States in respect of climate change, para. 456.