by The Law of War, formally known as International Humanitarian Law (IHL), was developed to regulate violence during armed conflict by limiting unnecessary suffering and protecting civilian populations. According to the International Committee of the Red Cross (ICRC), IHL governs both the conduct of hostilities and the protection of persons who are not or are no longer participating in conflict. Its legal framework is built around principles such as distinction, proportionality, and military necessity, all intended to strike a balance between humanitarian protection and military objectives.
Yet the Law of War emerged in a period when environmental degradation, climate stress, and ecological collapse were not understood as defining conditions of insecurity. The major instruments of modern IHL, including the Geneva Conventions and their Additional Protocols, were designed around assumptions that the humanitarian effects of military operations could largely be assessed through direct, immediate, and geographically bounded harm. Civilian suffering was conceived primarily in relation to casualties, physical destruction, and the immediate reverberations of military attacks rather than through long-term interactions with pre-existing environmental vulnerability.
Today, however, armed conflicts increasingly unfold in climate-stressed settings characterized by water scarcity, environmental degradation, food insecurity, and weakened infrastructure. In these contexts, military operations that may appear legally proportionate in isolation can generate cascading humanitarian effects far beyond what traditional legal analysis anticipates. Damage to a power grid, fuel depot, water pump, or port may not simply produce temporary disruption; it may accelerate systemic collapse where ecological resilience is already dangerously low.
This article argues that while IHL remains formally equipped to protect civilians during armed conflict, it contains a structural blind spot when applied to climate-vulnerable environments. Using Yemen as a primary case study, the article examines how acute water scarcity and environmental fragility interact with wartime destruction to magnify civilian harm. Yemen serves as a compelling proof of concept because it combines one of the world’s most severe pre-existing water crises with prolonged conflict and repeated attacks on essential infrastructure, making visible the limitations of a legal framework that tends to evaluate harm discretely rather than cumulatively.
The Legal Framework & Its Environmental Blind Spot
International Humanitarian Law is not entirely silent on environmental protection during armed conflict. It contains provisions aimed at limiting damage to both the natural environment and infrastructure indispensable to civilian survival. Under Article 54 of Additional Protocol I to the Geneva Conventions, parties to a conflict are prohibited from attacking objects essential for civilian survival, including drinking water installations, irrigation systems, and agricultural areas. Additional protections appear in Articles 35 and 55 of Additional Protocol I, which prohibit methods of warfare expected to cause widespread, long-term, and severe damage to the natural environment.
At first glance, these provisions suggest that IHL already possesses tools capable of addressing environmentally mediated harm. Water infrastructure, food systems, and ecological resources are formally recognized as legally relevant objects of protection. Yet these rules were largely drafted with exceptional environmental destruction in mind—such as scorched-earth tactics, toxic contamination, or large-scale ecological devastation—rather than chronic environmental fragility.
This creates an important legal gap in climate-vulnerable conflict settings. Existing protections tend to focus on the legality of specific attacks and visible environmental destruction, but they struggle to account for the interaction between military operations and pre-existing ecological stress. In countries already facing water depletion, drought, or infrastructural weakness, damage that appears limited in military terms may trigger disproportionate humanitarian consequences through cascading system failures.
Moreover, IHL provides little guidance on how environmental vulnerability should influence proportionality assessments. While the destruction of a water pump, port, or fuel depot may not independently constitute unlawful environmental damage, its consequences may become catastrophic where civilian survival depends on already fragile systems. The law therefore recognizes environmental harm, but it remains comparatively underdeveloped in addressing environmental fragility as a condition that magnifies civilian suffering.
The Case of Yemen: Anatomy of a Climate-Stressed Conflict
The armed conflict in Yemen, particularly following the 2015 intervention by the Saudi-led coalition against the Houthi movement, illustrates how climate vulnerability can transform the effects of otherwise legally assessable military actions into systemic humanitarian collapse. The significance of the Yemeni case lies not only in the scale of destruction, but in the fact that many of the actions contributing to humanitarian harm are not clearly prohibited under existing international humanitarian law when assessed in isolation.
Under the existing law of armed conflict, certain categories of infrastructure may lawfully be targeted if they qualify as military objectives. Dual-use infrastructure, such as ports, roads, fuel depots, and electricity networks, can be attacked when they contribute effectively to military operations and when their destruction satisfies the requirements of proportionality and military necessity. Even where civilian harm occurs, such attacks are not automatically unlawful if the expected incidental damage is not considered “excessive” in relation to the anticipated military advantage.
This doctrinal structure is central to understanding Yemen. For example, the port of Hudaydah has been repeatedly affected by military operations and restrictions during the conflict. Under IHL analysis, the port may be treated as a legitimate military objective due to its role in logistics and supply chains. Similarly, disruptions to fuel import routes or transport infrastructure may be assessed as lawful if they are tied to military necessity. The law does not prohibit such actions per se; rather, it regulates them through proportionality calculations conducted at the level of individual attacks.
However, Yemen demonstrates how this legal structure produces a critical blind spot when applied in a climate-stressed environment. Even when strikes or blockades are arguably lawful under distinction and proportionality, their downstream effects are magnified by environmental fragility. Yemen’s water system, for instance, is heavily dependent on diesel-powered pumps due to the absence of resilient public infrastructure. As a result, disruptions to fuel imports, whether through damage to infrastructure or restrictions on supply, can indirectly disable access to clean water across entire regions.
According to UNICEF Yemen WASH reports, millions of people have faced severely reduced access to safe drinking water during the conflict, largely due to the breakdown of interconnected systems rather than the destruction of water sources alone. Yet under traditional IHL analysis, these outcomes are difficult to fully integrate into proportionality assessments because the legal test focuses on the expected harm of a specific attack, rather than the cumulative impact on an already fragile environmental system.
The same dynamic is visible in the collapse of sanitation infrastructure and the spread of waterborne disease. According to the World Health Organization Yemen crisis reports, deterioration in water and sanitation systems contributed significantly to large-scale cholera outbreaks. However, these humanitarian consequences emerge not from a single unlawful act, but from the aggregation of multiple disruptions that, taken individually, may fall within the scope of lawful military conduct.
Yemen therefore exposes a structural limitation in how international humanitarian law operates in practice. The law does not necessarily fail to regulate individual acts of warfare; rather, it struggles to account for how environmentally fragile systems convert legally assessable military actions into cascading humanitarian crises.
The “Cumulative Harm” Problem
A key limitation in International Humanitarian Law becomes visible when looking at how harm is assessed in practice. The principle of proportionality is applied on a strike-by-strike basis, asking whether expected civilian harm from a specific attack is excessive compared to the military advantage. This means each incident is judged in isolation.
The problem is that humanitarian harm does not accumulate in isolated units. In conflicts like Yemen, repeated disruption of ports, fuel supplies, and electricity networks gradually breaks down interdependent systems such as water access, sanitation, and food distribution. Individually, each action may be considered proportionate or not clearly unlawful under IHL. Taken together, however, they can produce widespread humanitarian collapse.
This gap becomes sharper in climate-stressed environments. Where water scarcity and weak infrastructure already exist, even limited or repeated disruptions can have outsized effects. Yet proportionality does not formally require decision-makers to assess how environmental fragility will amplify harm over time.
As a result, IHL can legally evaluate each step correctly while still missing the overall pattern of cumulative destruction. The law captures isolated harm well, but struggles to account for system-wide collapse produced through repeated lawful actions in fragile environments.
Comparative Perspectives and Conclusion
The dynamics observed in Yemen are not unique. Similar interactions between conflict and environmental fragility can be seen in other climate-stressed regions where civilian survival depends on vulnerable infrastructure systems.
In the Lake Chad Basin, armed conflict involving non-state armed groups has unfolded alongside severe environmental degradation and shrinking water resources. As in Yemen, civilian livelihoods depend heavily on fragile ecological systems, particularly access to water and arable land. According to the United Nations Environment Programme, environmental stress in the region has significantly intensified humanitarian vulnerability in the context of armed conflict.
A similar pattern is visible in Somalia, where prolonged conflict intersects with recurring droughts and weak infrastructure. In such contexts, disruption to transport routes, water access, or fuel supply can quickly escalate into widespread food insecurity and displacement, even when individual acts of violence are not necessarily unlawful under international humanitarian law.
These comparative examples reinforce the central insight of this article: the legal framework of international humanitarian law is not absent or ineffective, but it is often analytically under-equipped to account for how environmental fragility reshapes the consequences of armed conflict.
This does not require abandoning the structure of IHL. Instead, it suggests the need for a more dynamic interpretive approach to existing principles—particularly proportionality—that better reflects cumulative harm and environmental vulnerability as part of the assessment of civilian impact.
Yemen therefore does not stand as an exception to the law of war, but as a stress test of its assumptions. It shows that in climate-vulnerable conflict zones, the legality of individual acts may no longer fully capture the humanitarian reality they collectively produce.
