In April 2026, the South China Sea was the scene of an escalation in aggressive state behaviour, as China deployed a fleet of fishing vessels and coast guard ships to form a physical blockade at the entrance of the Scarborough Shoal. The goal of the manoeuvre was to tighten its control over the hotly disputed maritime site. Although this fertile fishing ground traditionally and legally lies within the Philippines’ Exclusive Economic Zone, China also claims it as part of its territory, regularly deploying larger vessels to block local Filipino fishermen. In response, Manila has consistently dispatched its own coast guard to support its fishermen and assert its sovereign rights. The Scarborough Shoal is only one of several strategically important fishing grounds embedded within a complex network of overlapping maritime and territorial claims across the South and East China Seas. These persistent tensions, involving other regional powers such as Japan, Taiwan, Thailand, Vietnam, Malaysia or Indonesia, could carry a latent risk of escalating into a wider armed conflict.

While maritime sovereignty and tactical posturing are not the only drivers of tension in the South China Sea, the governance of fishing resources has emerged as a critical issue in a power struggle essential to state survival. Many East and Southeast Asia economies depend on the exploitation of these shared fishing grounds, just like the daily diets of their populations, which rely heavily on marine resources. According to the Food and Agriculture Organization (FAO), more than three billion people worldwide rely on fish as a primary source of protein. The intensive exploitation of fish stocksin the South China Sea has therefore evolved from a localized environmental concern into a zero-sum flashpoint directly affecting regional security and geopolitical stability.

A new factor could make things worse and further exacerbate these tensions. Scientists are concerned on the possible emergence of a “Super El Niño” event during the 2026 and 2027 years. The phenomena, that emerges from variation in winds and sea surface temperatures over the Pacific Ocean, can trigger significant shifts in the distribution of fish stocks, pushing fishermen farther from their traditional fishing grounds and increasing competition over already contested waters. In one of the world's most strategically sensitive maritime regions, such ecological disruptions may have consequences that extend far beyond the environment.

Research from the International Journal of Foreign Affairs “Marine Policy” suggests that fisheries disputes in the East and South China Seas have historically been more likely during El Niño episodes, raising important concerns for policy makers and diplomats on how to act and anticipate these upcoming events. Indeed, El Niño years are associated with a significantly higher risk of fisheries-related conflicts escalating into armed conflicts: “Depending on the estimator, militarised fisheries disputes are 223% or 204% more likely under El Niño conditions than under non-Niño conditions”. Almost 80% of the militarised fisheries disputes between states bordering the East and South China Seas took place during El Niño episodes.

The Scarborough Shoal dispute is indeed far from an isolated case. The Diaoyutai/Senkaku Islands, an uninhabited archipelago administrated by Japan since 1972 and located between Japan, Taiwan and mainland China, are surrounded by some of the richest fishing grounds in the East China Sea. The three parties claim sovereignty on this territory, and for decades fishermen from China, Taiwan and Japan have competed to operate in these productive waters. Tensions intensified significantly in 2012 when the Japanese government purchased several of the islands from a private owner, leading China to interpret it as a challenge to its sovereignty claim. Chinese and Japanese coast guard vessels have regularly confronted one another in the surrounding waters while escorting and protecting their respective fishing fleets. Both countries have also increased the presence of their military aircraft and naval vessels nearby, turning what is fundamentally a dispute over territory and access to marine resources into a sensitive geopolitical area.

As a matter of fact, the East and South China Seas are already fisheries conflict hotspots. Demand for marine resources is particularly high in East and Southeast Asia, where annual fish and seafood consumption exceed 40 kilograms per capita in countries including Hong Kong, South Korea, Malaysia, Indonesia, Vietnam, China, and Japan. China alone represents around 36% of the world’s fish consumption and possesses the largest distant-water fishing fleet. As populations and consumption continue to grow across the region, competition over increasingly scarce fishing grounds is likely to intensify. Fish stocks in the South China Sea have already fallen by between 70% and 95% from historical levels in some areas due to overfishing and habitat degradation. This overfishing trend is also driven by fisheries nationalism, as countries assert their sovereignty by encouraging their fishermen to step up their fishing efforts. China and Vietnam are for example subsidising fuel and the construction of more efficient vessels.

The risk of conflict is therefore increased by the growing gap between the rising demand and declining resources. These waters are particularly vulnerable to aggressive behaviour from its coastal states and El Niño could act as a threat multiplier in a region that is already politically fragile. However, shared ecological vulnerabilities can create incentives for cooperation even among states with competing resources. In this situation of complex interdependence, military power becomes less relevant. The cost of conflict is more important compared to the cost of anticipation and cooperation, because the sustainability of fish stocks depends on the collective management of a shared ecosystem. While military power may help a state to secure temporary access to fishing grounds, it cannot prevent overfishing and restore scarce stocks. An armed conflict would likely disrupt trade, damage even more fishing industries and increase food insecurity.

By contrast, scientific cooperation and political dialogue has often proved more resilience than unilateral decision. The Coral Triangle Initiative brings together six Southeast Asian states around the objective of preserving marine biodiversity, by monitoring data and following the evolution of coral cover in the region. The initiative was able to show that coral cover in the East Asian Seas region was substantially greater in 2019 than in 1983, despite bleaching events during the 2010s. Similarly, the Southeast Asian Fisheries Development Centre (SEAFDEC) illustrates the depoliticization of technical knowledge, by providing expertise on fish stocks management and sustainable catch levels.

The ASEAN fisheries cooperation mechanisms further extend this logic, creating habitual channels of communication among fisheries ministries that persist independently of the diplomatic tensions surrounding maritime boundaries. Even China, despite its assertive posture on territorial claims, has engaged in ASEAN-China marine scientific cooperation, suggesting that ecological interdependence can open channels of dialogue that political negotiations alone might struggle to sustain. Shared fisheries research, stock monitoring and marine conservation may represent a new generation of confidence-building measures, better adapted to an era defined by climate change.

Yet climate change and the rapid environmental impacts of El Niño require a more robust and proactive framework for ecological cooperation. While these specific pockets of cooperation existed, they have not led to a broader regional framework. Despite thirty years of warnings from scientists, territorial disputes have meant that bilateral or regional cooperation initiatives have all failed or remained largely marginal. They focused on the coastlines of the states rather than stretching into the actual disputed conflict areas. The failure of a Spratly Islands Marine Peace Park is a good illustration of the promises and limits of ecological diplomacy. The initiative sought to transform one of Asia's most contested maritime spaces into a zone of scientific cooperation and environmental protection. Unlike some regional fisheries organisations, the proposed peace park lacked a binding treaty, enforcement tools and a clear governance structure that could have overcome concerns over sovereignty. It remained largely an academic and diplomatic proposal rather than an operational institution.

As the El Niño effect increases pressure on marine ecosystems and intensifies competition over resources, the risk of confrontation in the East and South China Seas is likely to rise. Climate change acts as a threat multiplier, exacerbating existing tensions over sovereignty and food security. But its high-cost consequences also make conflict unsustainable and create more cooperation opportunities.

The lesson of El Niño is therefore that climate shocks do not automatically create conflict. It creates pressure. Whether that pressure leads to confrontation or cooperation depends on diplomacy. Ecological diplomacy may prove to be not only an environmental necessity, but also a strategic imperative for peace and stability in the East and South China Seas.