Over the past years, two important challenges to traditional conceptions of international law have come to the fore: pluralism and informality. Pluralism refers to the fact that global society is characterized by multiple legal systems that frequently overlap. Informality refers to the increasing relevance of non-traditional actors, processes and outputs in the realm of international law. Two recent books provide important contributions to enhancing our understanding of these challenges. In the first book, Nico Krisch presents a powerful plea that in a ‘postnational’ context legal pluralism is to be preferred over its alternative, transferring constitutionalism to the global level. In the second book, Joost Pauwelyn, Ramses Wessel and Jan Wouters offer a collection of essays that seek to further knowledge of the concept, legal nature, impacts and accountability of ‘informal international lawmaking’. In reviewing these two books, this review essay seeks to identify avenues for further inquiry in the area of transnational environmental law.

Carbon leakage – the increase of greenhouse gas emissions in foreign jurisdictions following the introduction of domestic or regional climate mitigation measures – raises key questions in the climate change debate. This includes whether carbon leakage constitutes a threat to the environmental integrity of climate policies and, if so, how this could be mitigated. Through the use of four hypothetical models of international climate change regime, this article argues that international climate change law is a key factor in answering this two-part question. Firstly, the article demonstrates that the architecture of international climate change law affects whether carbon leakage can be considered as undermining the mitigation objective of climate policies. Secondly, it draws attention to the interaction – and potential tension – between carbon leakage prevention measures and international climate change law.

Groundwater is a largely unseen common pool resource. Yet, driven by strong economic incentives, whether or not encouraged by existing policies, and the difficulty to exclude others, groundwater users are competing with each other to extract as much as possible, with devastating consequences for its sustainability. The challenges faced for sustainably managing such common pool resources, on which people have established de facto individual rights, are manifold. However, creating a market for trades of some kind in ecosystem services associated with groundwater could actually enhance the protection of this critical resource on the basis that protection can benefit individual groundwater users economically as well as provide a broader public good. This article uses Elinor Ostrom's design principles as an analytical tool to examine how market-based approaches such as payments for ecosystem services (PES) fit with some of the governance models that could be used to protect and enhance groundwater as a common pool resource. It argues that while there are specific design challenges to be overcome, PES as an institutional tool can align with Ostrom's ideas for the governance of groundwater.

Floods are not merely ‘natural’ disasters; rather, they emerge as socio-natural phenomena shaped by political, social, and economic processes. Law plays a pivotal role in producing and sustaining these processes and contributes to the creation of unjust environments. Drawing on political ecology and environmental history, this article analyzes the role of law and its interactions with colonialism and capitalism in the Damodar river valley in Eastern India. The Damodar river valley is an intensely engineered and hazardous region, a site of multiple interventions and developmental and ecological experiments for over a century. Colonial and post-colonial legacies have left a lasting imprint on legal, policy, and institutional frameworks, establishing a path-dependent trajectory for addressing future climate change adaptation challenges. While focusing on a specific case study, the article's approach and findings have broader significance, especially in the context of climate adaptation. The central argument underscores the need to understand the political and legal dimensions of flooding, and reinforces the need for a shift beyond incremental adjustments that do not tackle the underlying structures that produce the injustices associated with floods. It highlights the importance of ‘transformative adaptation’ approaches that address the root causes of climate-related disasters, such as restructuring power relations between actors, reconfiguring governance structures, and scrutinizing ideologies that mediate how water is used and distributed.

In recent years, China has expanded its national weather modification programme to exploit climatic resources and adapt to climate change. The unprecedented scale of China's weather modification programmes has raised concerns over potential environmental impacts, including transboundary impacts. This article analyzes the domestic governance of weather modification in China and the extent to which this legal framework satisfies China's obligations under customary international law to minimize risks of significant transboundary harm. We find that existing arrangements do not satisfy procedural obligations under customary international law; nor do they adequately address the risks of environmental impacts associated with the increased use of weather modification. Procedures for transboundary environmental impact assessment (EIA) and engagement with regional neighbours are needed for China to comply with international law and promote stability in the region.

International nature protection law has developed without a coherent plan, with disparate governance instruments each largely evolving within their own separate sphere. Yet, many other issues are closely linked to the challenges of nature degradation, such as developmental challenges, climate change, food security and food safety, disease prevention, and rural poverty. These interconnections have partly been recognized in Agenda 21 and more recently in the Aichi Biodiversity Targets. This response commentary draws on and extrapolates further the conclusions of Patricia Farnese in ‘The Prevention Imperative’, published in this issue of Transnational Environmental Law, and argues for a more coherent approach and effective leadership in this area of global regulation, along with a more flexible and holistic approach to governance responses.