The Local Turn in International Climate Law: Cities, everywhere and nowhere

Climate change represents one of the most significant global challenges of our time, with far-reaching implications for environmental sustainability, economic development, public health, and social justice. As the impacts of climate change become increasingly evident, legal systems at the national, regional, and international levels are being called upon to develop effective frameworks for mitigation, adaptation, accountability, and resilience. Given the pivotal role that law can play in shaping climate governance, this blog series, edited by Dr Azadeh Chalabi, brings together academics, legal practitioners, and policymakers to contribute blog posts on the theme “Law and the Climate Crisis". Contributions to the series seek to foster critical engagement with the evolving relationship between law and climate change while exploring innovative legal responses to contemporary environmental challenges.

Camilo Cornejo Martinez, Lancaster University

Keywords: International Climate Law; Cities and Local Governments; Climate Multi-Level Governance; Climate Governance; Non-State Actors.

During the heatwaves that scorched Europe this summer, something curious caught my attention. Following a trend observed in previous summers, the story was increasingly told through cities. The headlines spoke about London, Paris, Rome, Madrid and Berlin, rather than, more conventionally, the UK, France, Italy, Spain, or Germany. These cities became the protagonists of the climate crisis: transport systems struggling under extreme temperatures, hospitals preparing for surges in admissions, parks transformed into cooling spaces, and local authorities urging residents to stay indoors. This reflects the increasingly recognised dual role of cities in the climate crisis. They are both major sources of greenhouse gas emissions and among the most important arenas for climate action. Climate change appeared, above all, as a city experience.

This raises an important socio-legal question. If cities are increasingly where climate change is experienced, managed and governed, has international climate law begun to recognise them? I suggest that it has. Not by granting cities international legal personality or making them subjects of international law, but by gradually incorporating them systematically into the architecture through which international climate obligations are interpreted and implemented. That evolution can be seen in climate science, treaty design, and the accumulated practice of the UN climate regime.

What climate science tells us about cities

In contrast to previous assessment cycles, the IPCC Sixth Assessment Report (AR6) places cities at the centre of both mitigation and adaptation efforts. Urban areas are major sources of greenhouse gas emissions and are highly exposed to climate-related risks, including extreme heat, flooding, infrastructure vulnerability, and social inequalities (pp. 869-870). At climate level governance, the AR6 identifies well-aligned multi-level governance as one of the enabling conditions for deep emissions reductions and climate-resilient development. International, national and local institutions are no longer viewed as operating in isolation but as mutually reinforcing components of an integrated and mutually dependent governance system. Regional and national climate goals become considerably more effective when local governments participate in designing and implementing them (911-913).

This IPCC city turn, confirmed by the Special Report on Climate Change and Cities may have legal implications. Because international courts increasingly treat the IPCC as the benchmark for the ‘best available science,’ its growing focus on cities is likely to influence the interpretation of climate obligations.

What the scholarship sees

Legal scholarship has, of course, recognised the growing importance of cities in climate governance. Much of this literature has been shaped by two influential perspectives. The first centres on city diplomacy. Cities have established international offices, joined transnational municipal networks (e.g. C40 or the Global Covenant of Mayors), exchanged policy solutions, and at times sustained climate ambition even when national governments have retreated. The widely cited ‘We Are Still In’ declaration, issued following the United States' announcement of its withdrawal from the Paris Agreement, remains one of the clearest illustrations of this phenomenon. The second perspective emphasises multi-level governance as a framework for understanding climate action. This scholarship highlights how effective climate governance increasingly depends on interactions across different levels of government, as well as with non-state actors. It provides an indispensable lens through which to analyse the complexity of contemporary climate reaction.

Yet these perspectives also leave an important legal question to further explore. They explain how cities participate in climate governance, but they tell us less about how international climate law itself has evolved to accommodate this reality, which will be initially explored in the following sections.

The treaties stayed state-centred, but not entirely

UNFCCC, Kyoto Protocol, and Paris Agreement remains firmly State-centred. States continue to negotiate treaties, submit nationally determined contributions, and bear international responsibility for complying with their obligations. Nothing in the Paris Agreement alters the constitutional foundations of international climate law. At the same time, however, Paris Agreement (more evidently) quietly incorporates a much broader understanding of climate governance and policy solutions. For instance, Article 7 recognises adaptation as a challenge with local, subnational, national, regional and international dimensions. Capacity-building extends beyond central governments, while participatory approaches and locally informed decision-making appear throughout the Agreement.

Rather than relocating legal responsibility away from States, the Paris Agreement acknowledges that many international commitments can only be realised through institutions operating across multiple territorial levels, which lead an opportunity for cities.

Cities in international practice: Three emerging roles

From the Paris Agreement onwards, successive COP decisions increasingly refer to cities, subnational authorities and local actors. Read together, these decisions suggest that cities perform at least three interconnected legal functions within contemporary international climate law:

• First, cities are increasingly acknowledged as the sites where the impacts of climate change and the distributive consequences of climate transitions are most tangibly experienced. COP decisions have progressively identified housing, urban mobility, city employment, public health, and urban infrastructure as areas where climate governance intersects with questions of equity and social justice. The Silesia Declaration Solidarity and Just Transition provides a notable example, foregrounding vulnerability, adaptation, and just transition concerns at the urban and local scales.

• Secondly, cities increasingly appear as implementation partners, acting in support of States' obligations. Decisions adopted since Paris Agreement repeatedly acknowledge that achieving international climate objectives depends upon action by subnational authorities. Whether through adaptation planning, resilient infrastructure, mitigation programmes or cooperative initiatives, cities are progressively written into the machinery through which States discharge their own international commitments (e.g. COP Decision 8/CP.24 ‘National Adaptation Plans’ § 12).

• Thirdly, cities are emerging as governance actors in their own right. Here the practice goes beyond supporting national commitments: recent decisions encourage municipalities to set their own goals, design and assess their own climate strategies, and engage directly with other actors through knowledge-sharing, monitoring, reporting and integrated city transition pathways. The COP29 Declaration on Multisectoral Action Pathways to Resilient and Healthy Cities perhaps illustrates this most clearly by placing local governments among the actors responsible for designing and advancing urban climate action across sectors. This mirrors a wider pattern beyond the climate regime: UN human rights bodies increasingly treat local governments as duty-bearers, promoting rights-based urban climate action through the growing Human Rights Cities movement.

Concluding with a note of caution: inclusion v/s empowerment

There is, however, an important reason to resist an overly celebratory account. Recognition within international climate law does not necessarily translate into empowerment. As recent scholarship has argued, many cities (particularly in the Global South) remain constrained by limited legal authority, fiscal dependence, and financial structures that shape what forms of climate action are politically and economically possible. Their growing visibility within international climate governance therefore coexists with persistent inequalities in access to finance, institutional capacity, and political autonomy.

This reminder brings us back to the central argument. International climate law remains a state-based legal order: cities are not subjects of international law and must operate within national legal frameworks. Yet the question is no longer whether cities matter for climate governance. They clearly do. As increasingly recognised in international practice, climate law is realised not only through treaty negotiations but also through planning decisions, public transport systems, housing policies, and resilient infrastructure. International climate goals are increasingly interpreted, implemented, and experienced through urban institutions and alongside a broader range of non-state actors. This is where climate law will increasingly succeed or fail: not only in negotiating rooms, but in the housing, transport, and energy decisions taken across the world's cities. Recognising that shift, supporting cities (regulatory and financially) and taking cities seriously as actors in their own right, is no longer peripheral to climate governance. It is central to it.

Author Bio

Chilean lawyer (Universidad de Chile – Corte Suprema de Chile), PhD candidate in Law at Lancaster University, researching just transition and international climate law. LLM in Human Rights and the Environment (Lancaster University) and a Master's in Public Law (Universidad de Chile).

Affiliated with the Pentland Centre for Sustainability in Business; part-time research assistant at the Grantham Research Institute on Climate Change and the Environment (LSE); Assistant Professor at the Universidad de Chile; and a tutor at Lancaster University.

Research areas of practice and interest: international environmental law, just transition and SDG, climate governance, environmental human rights, legal epistemologies, and the legal role of new environmental actors (local governments, future generations, and rights of nature).