Dr Marja Lehto is Ambassador for International Legal Affairs at the Ministry for Foreign Affairs of Finland, and Adjunct Professor of International Law at the University of Helsinki. She was a member of the United Nations (UN) International Law Commission (ILC) and served as the Special Rapporteur for the topic “Protection of the Environment in Relation to Armed Conflicts” from 2017 to 2022. Dr Lehto is also a member of the Council of the International Institute of Humanitarian Law since 2019. She has formerly served, inter alia, as Legal Adviser to the Finnish UN Mission in New York (1995–2000), as Head of the Unit for Public International Law (2000–09), and as Finland's Ambassador to Luxembourg (2009–14). For most of her career, she has worked on issues related to international peace and security, including international criminal justice and international humanitarian law (IHL), and she has published on a broad range of international legal questions related to the law of the sea, international environmental law (IEL), State succession, use of force, armed conflicts, terrorism and cyber security.

In 2020, the International Committee of the Red Cross's work on the protection of the natural environment under international humanitarian law (IHL) produced the Committee's Guidelines on the Protection of the Natural Environment in Armed Conflict (ICRC Guidelines), an update of their 1994 predecessor. The ICRC Guidelines consist of thirty-two rules and recommendations under IHL, each accompanied by a commentary explaining their legal basis and providing guidance for interpretation. This article presents an overview of the context surrounding the Guidelines, certain key legal content, and practical implications for the conduct of parties to armed conflict as they fight.

The scope of protection of the environment in relation to armed conflict has continued to expand since the issue was first introduced on the international agenda in the 1970s. Today, it is recognized that the environment is a prima facie civilian object and as such it is entitled to the same layers of protection during an armed conflict as any civilian person or object. Thus, there is a legal obligation to prevent environmental harm in armed conflict, before the event. Given the magnitude of environmental damage that can be anticipated in relation to armed conflict, the obligation to prevent such damage in the first place is critical. In this regard, it is important to note that the legal obligation to prevent environmental harm originates from international environmental law. Furthermore, the obligation to prevent harm is an ongoing obligation. This article illustrates that the general preventive obligations found in international environmental law can shed much-needed light on the general preventive obligations already established under the law of armed conflict, in furtherance of environmental protection.

Since its launch in 2021, the Climate and Environment Charter for Humanitarian Organizations (the Charter) has been signed by hundreds of humanitarian actors across the world, including local and national organizations, United Nations agencies, National Red Cross and Red Crescent Societies, and large international NGOs. The Charter's development grew out of a sector-wide recognition that humanitarians have a role to play in addressing the crises of climate change and environmental degradation, and that fulfilling this role would entail changing how they work. Two years into its existence, the Charter has helped build momentum towards this change and has provided a useful measurement tool for how much remains to be done.

This paper traces the origins, inspiration and process of the Charter from the perspective of the present authors, who co-led the Charter's development. The article highlights some of the challenges that we faced and how these were addressed. In taking stock of progress towards the Charter's goals, the article flags areas where further effort is needed to adequately strengthen the humanitarian response to the climate and environmental crises.

In the face of the triple planetary crisis, which includes climate change, biodiversity loss and environmental degradation, there is growing recognition that the environment needs to be re-evaluated and better protected. Recent developments, such as a values assessment by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES),1 the concept of biocultural rights and the acknowledgment of granting rights to nature, emphasize the intrinsic value of the environment and endorse the understanding of the interconnectedness between humans and non-human entities. These developments are also increasingly evident in legal frameworks; for instance, several domestic legal systems now accept the rights of nature and grant legal standing to natural entities. This expansion in our understanding of the environment challenges the traditional anthropocentric focus of international law, which has primarily prioritized human rights and interests, perceiving humans as having dominance over nature and the liberty to harness its resources. Simultaneously, international environmental law is increasingly recognizing the interdependence of ecosystems and species. This acknowledgment drives the promotion of approaches to environmental management and conservation that centre around ecosystems and local communities. The present article looks at how to reconcile these heightened environmental values and the legal norms in armed conflict by examining two examples: the safeguarding of protected areas and the restoration of the environment post-conflict. By analyzing the changing values and legal developments in this area, the article offers legal and practical tools to support the protection of nature's intrinsic value in future warfare.

This article outlines and evaluates the US perspective on how treaty and customary international law protect the natural environment during international armed conflict. It surveys the relevant treaties to which the United States is a party and examines US views on their pertinent provisions. It then assesses claims that the environmental obligations residing in the 1977 Additional Protocol I to the 1949 Geneva Conventions have attained customary status, outlines the United States’ rejection of those claims, and evaluates the reasonableness thereof. Finally, it highlights ambiguities in certain US environmental positions, the resolution of which would bring much-needed clarity to the law.

In November 2022, eighty-three States endorsed the Political Declaration on Strengthening the Protection of Civilians from the Humanitarian Consequences Arising from the Use of Explosive Weapons in Populated Areas (Political Declaration). The Political Declaration is a new and significant development in the long-standing and ongoing efforts to protect civilians from the use of explosive weapons in populated areas – an issue which has been of growing concern for a number of states, the United Nations, the International Committee of the Red Cross and civil society for more than a decade.

The use of explosive weapons in populated areas has been documented to result in widespread civilian deaths and injuries as well as longer-term harm to civilians resulting from damage to or the destruction of hospitals, water and sanitation systems and electrical power grids. Although less researched, the use of explosive weapons in populated areas also plays a prominent role in damaging and destroying the environment in situations of armed conflict.

This article examines the potential of the new Political Declaration for strengthening the protection of the environment. An express reference to the environment, and the impact of explosive weapons thereon, exists only in the Declaration's preamble, but the lack of express references to the environment in the Declaration's operative commitments does not mean it lacks potential as a tool for strengthening the protection of the environment. On the contrary, the preambular reference provides an important basis on which to argue that the armed forces of endorsing States must consider the protection of the environment in their efforts to implement a number of the Declaration's key operational commitments.

Around 50 million people across the world are affected by urban warfare. When conflict occurs in cities, the natural environment has historically been relegated to an afterthought, but both the immediate and long-term environmental consequences of urban warfare are serious. This article looks at actions that can be taken to protect the natural environment – and through this, the population – against the effects of urban warfare when fighting in urban areas. It is intended to be a part of the conversation about what parties to armed conflict can and should do to give effect to their legal obligations under international humanitarian law and international law more broadly, with a specific focus on the natural environment when fighting in urban areas.

This article explores the legal obligations of Occupying Powers with regard to climate change adaptation for local populations and their environment under the law of occupation, specifically in the context of prolonged belligerent occupations. It focuses on the critical matter of water and food security, in light of the increasing frequency and severity of extreme weather events. After shedding light on the intricate issues that arise at the intersection of climate change and belligerent occupation, the article argues that the general obligations incumbent upon the Occupying Power under occupation law, when viewed through a climate lens, can be construed as addressing the heightened climate vulnerability faced by occupied populations.

Actors engaging in a diverse set of environmental protection activities are experiencing serious difficulties executing their mandates during armed conflict, leading to environmental harm that could otherwise have been mitigated. This article examines to what extent the international legal and policy framework can ensure the protection of environmental protection actors during armed conflict. It is argued that environmental protection actors can be seen either as part of civil defence organizations or as humanitarian relief actors, and are therefore covered by special protections under international humanitarian law. However, two main challenges remain: (1) despite these existing provisions, environmental protection actors may still face access and safety issues during armed conflict, and (2) within this framework, environmental protection activities must be linked to civilian needs and cannot be conducted based on ecocentric motivations. To overcome these challenges, the article introduces the concept of “environmentarian corridors”. Environmentarian corridors would allow for the unimpeded movement of environmental protection workers and resources through contested territory and into emergency areas to protect the environment. They would also serve to increase awareness about obligations to protect the environment and would help to ensure the safety of environmental protection actors during armed conflict, as the role and mandate of these actors is explicitly accepted by stakeholders. Additionally, environmentarian corridors offer potential for conducting environmental protection activities on ecocentric grounds. The article concludes by advocating for stakeholders to employ the provisions and concepts articulated herein as a means to further promote and strengthen initiatives aimed at protecting the environment during armed conflict.

Vulnerable ecological areas are often seriously impacted by armed conflicts. In theory, these areas could benefit from the safeguards offered by the international humanitarian law (IHL) regimes of “demilitarized zones” and “undefended localities”, but in practice, these regimes – which are designed to protect human beings from the violence of hostilities, and whose application entirely depends on the goodwill of belligerents – are rarely triggered to protect the environment as such. However, international environmental law (IEL) contains a rich and diversified normative framework which organizes the establishment and management of areas of major ecological importance. While this framework has not primarily been conceived to apply to war-related situations, it could nonetheless play a substantive role in strengthening the IHL normative regimes in two respects. Firstly, it could provide interpretative guidance for these regimes so that they can be oriented towards more “ecocentric” purposes and can be read in accordance with the most advanced IEL standards and mechanisms governing biodiversity hotspots (the “environmentalization” of IHL). Secondly, IEL norms and practices could directly apply during warfare and thus complement IHL in many respects. That said, the co-application of IEL and IHL raises difficult issues of compatibility between these regimes, requiring inter alia that the IEL framework governing protected areas be adapted to the needs and specificities of armed conflicts (the “humanitarization” of IEL).

Protected areas safeguard biodiversity of global ecological importance, even throughout armed conflicts. The International Law Commission's Principles on Protection of the Environment in Relation to Armed Conflicts propose that certain ecologically important areas could be designated as protected zones during armed conflicts. This article uses a geospatial analysis of armed conflicts and Key Biodiversity Areas and three case studies to inform recommendations on how the protection of ecologically important areas could be enhanced through visibility, local actors and international stakeholders as part of a broader interpretation of a protected zone.

While the law of State responsibility, particularly the principle of full reparation, provides general guidance for achieving full reparation, it is not quite obvious what kinds of reparation qualify as “full” and how to actualize full reparation. This article centres on the principles, approaches and methods surrounding full reparation for armed conflict-related environmental damage in the law of State responsibility. It examines how the environment is legally defined as an object of protection under international law, and discusses practical challenges in international compensation for wartime environmental damage. In doing so, it ascertains the underlying objective of full reparation, develops an approach to assessing wartime environmental damage, and draws on experiences of international jurisprudence to quantify compensation for wartime environmental damage.

Throughout history, armed conflicts have frequently seen serious harm committed against the natural environment. From the early 1960s to 1971, the United States used Agent Orange to defoliate large tracts of Vietnamese forests. In the 1990s, Saddam Hussein vengefully ordered the burning of Kuwaiti oil wells, resulting in massive pollution to the air, land and surrounding seas. More recently, ecocentric harm has been documented in the Colombian civil war, by the so-called Islamic State group, and in the Ukraine conflict, among others. Whilst international humanitarian law (IHL) contains several prohibitions against environmental harm, the most striking is Article 55(2) of Additional Protocol I, whereby “[a]ttacks against the natural environment by way of reprisals are prohibited”. Although this provision appears absolute and unconditional, critical questions persist regarding its status under customary international law and its applicability in non-international armed conflicts. Moreover, its criminalization has not been explored in the jurisprudence of international courts or in the relevant scholarly literature, despite the fact that penal sanctions against individuals are an important factor for enforcement of environmental protections.

To fill the lacuna, the following analysis examines the prohibition and criminalization of reprisals against the natural environment. It reviews conventional and customary international law to determine the current status of a putative criminal prohibition and its potential as lex ferenda. Importantly, it also assesses the relevance of reprisals against the natural environment for prosecutions under existing war crimes, such as attacks on civilian objects and destruction of enemy property. It generates novel insights for the application of international law to ecocentric harm, including that (1) reprisals against the natural environment are not criminal per se, but (2) conceptualizing the environment as a civilian object opens up clear paths for prosecuting attacks, including reprisals, against it; (3) the inherently intentional nature of reprisals has far-reaching implications for their prosecution; (4) reprisals can significantly impact the pivotal test of military necessity which arises in criminal prohibitions such as that found in Article 8(2)(b)(iv) of the Rome Statute; and (5) situations of reprisals could impact the application of the proposed definition of ecocide.

Traversing IHL and international criminal law (ICL), the article identifies ways in which these traditionally anthropocentric bodies of law can be reoriented to accommodate ecocentric values. This reconceptualization is significant, as the prospect of criminal sanctions is critical for deterring potential perpetrators and potentially adds a basis for reparations designed to remediate damage to the environment. The assessment redresses the fact that the natural environment has been seen as a peripheral matter under both IHL and ICL and has remained under-explored despite the ongoing destruction wrought on nature including during armed conflict. It seeks to elevate the environment to a core protected value under these legal regimes, as a reflection of our increasing awareness that the natural environment is critical for the well-being of current and future generations and our growing appreciation of the intrinsic importance of protecting nature.

The growth of access to the internet, wide availability of smart phones and increased public access to remote sensing data from hundreds of satellite systems have spurred a revolution in tracking the linkages between armed conflict and environmental damage. Over the last decade, a growing community of open-source investigative experts, environmentalists, academics and civil society groups have applied these methods to document war crimes, human rights violations and environmental degradation. These developments have created new opportunities for building accountability and transparency. The wealth of data on conflict-linked environmental damage has already been successfully leveraged to address acute and long-term environmental health risks and inform humanitarian response and post-conflict environmental assessments in Iraq, Syria and Ukraine. There are, however, larger questions on how to best make use of these data streams and information layers, and how to navigate the opportunities and limitations of these developments. This article will outline the new developments in this field and provide recommendations to ensure that data is used responsibly and effectively to strengthen accountability for environmental damages as a result of armed conflict.

The law of belligerent occupation permits the Occupying Power to administer and use the natural resources in the occupied territory under the rules of usufruct. This provision has no counterpart in the provisions of humanitarian law applicable to non-international armed conflicts, which may suggest that any exploitation of natural resources by non-State armed groups is illegal. The International Committee of the Red Cross's updated 2020 Guidelines on the Protection of the Environment in Armed Conflict did not touch on this issue, and nor did the International Law Commission in its 2022 Draft Principles on the Protection of the Environment in Relation to Armed Conflicts, where it applied the notion of sustainable use of natural resources instead of usufruct. The present paper aims to fill this gap. It first reviews the development of the concept of usufruct and then studies whether the current international law entitles non-State armed groups with de facto control over a territory to exploit natural resources. By delving into the proposals raised by some commentators to justify such exploitation for the purpose of administering the daily life of civilian populations, the paper advocates for a limited version of this formula as the appropriate lex ferenda. In the final section, the paper discusses how situations of disaster, as circumstances which may preclude the wrongfulness of the act, may justify the exploitation of natural resources by non-State armed groups in the current international legal order.

Given the increasing size and functions of United Nations (UN) peace operations (POs) and the fact that they often operate in contexts where natural resources are degraded, POs have repercussions on the environment. Yet, there is not much literature on their obligations regarding the protection of the environment in relation to armed conflicts. This article provides insights into the obligations of POs in relation to armed conflict. First, it highlights POs’ customary international environmental law obligations. Second, it delves into their environmental obligations under the UN's internal rules and the host State's laws. Third, it explores obligations that arise from their mandates. In each of these sections, the article highlights the relevance and application of these obligations in armed conflicts. The last section examines the obligations of POs to protect the natural environment under international humanitarian law.

The protection of the environment during warfare attracted significant attention in the 1990s, especially after the 1990–91 Gulf War. It became clear at that time that the few rules provided by international humanitarian law (IHL) aimed specifically at protecting the environment were insufficient. Various studies have since been undertaken with the aim of strengthening that protection from an IHL perspective. It is only recently that scholars and institutions like the International Law Commission have started to reflect on how to better protect the environment in armed conflict through the lens of another branch of international law, namely, international environmental law (IEL). Such an approach has involved examining the interplay between IHL and IEL, and scholars have subsequently proposed and then elaborated on frameworks in that respect. This paper intends to identify common trends of those frameworks and to critically appraise them, with the aim of providing a suitable approach to the interplay between IHL and IEL.

Both gender and the environment have traditionally been positioned at the periphery of international humanitarian law (IHL). In recent decades, there has been important progress in moving both concerns closer to its centre; to date, however, an understanding of the intersection of gender and the environment in the legal regulation of armed conflict remains largely underdeveloped. Nevertheless, as the present article documents, there are important similarities in strategies pursued to advance both gender and the environment from the periphery to the mainstream of IHL, namely: first, a focus on sources of IHL, in particular concretizing arguably limited specific treaty content with interpretive guidance and implementation frameworks; second, a conceptual critique of prevailing definitions of “harm” in IHL; and third, advancing, through close empirical documentation and household-level analysis of conflict's effects, understandings of harm that capture so-called “second-round” effects of conflict. Recognizing these important affinities between gender and environment work in IHL, this article draws on these insights to propose a typology of gendered environmental harm in conflict. The article concludes with proposals for enhancing the legal and operational capture under IHL of the gender–conflict–environment nexus.