Climate change is transforming the South China Sea into a human security frontier, displacing vulnerable coastal communities and driving irregular maritime movement across borders. ASEAN’s current maritime governance overlooks climate mobility and integrating it into regional rules and institutions is essential to prevent escalating humanitarian crises from devolving into strategic instability.
Between 2011 and 2020, Southeast Asian countries accounted for 15 percent of the Asia-Pacific population affected by disasters and one-quarter of all fatalities. By 2050, the East Asia and Pacific region is projected to see as many as 48.4 million internal climate migrants. This indicates that climate change is transforming the contested waters of the South China Sea into a critical human security frontier. Despite this, the South China Sea is typically framed as a site of territorial disputes, naval competition, and great-power rivalry, overlooking a quieter but equally destabilising force: the intensifying nexus of climate change and human displacement.
Sea-level rise, saline intrusion, and the catastrophic loss of livelihoods in the fishing and agricultural sectors are pushing coastal communities to relocate both internally and across international borders, transforming migration into a fundamental governance challenge. Despite growing evidence of these shifts, maritime governance frameworks for the South China Sea rarely address human mobility. Association of Southeast Asian Nations (ASEAN) mechanisms and regional maritime agreements prioritise state sovereignty, freedom of navigation, and traditional military security while largely ignoring the growing reality of displacement.
Emerging Crisis
Millions in Southeast Asia face displacement due to climate impacts by mid-century. Coastal and deltaic regions closely tied to the South China Sea—specifically the Mekong, Red River, and Manila Bay—are especially exposed. In these frontiers, livelihoods depend heavily on fisheries, aquaculture, and small-scale agriculture. However, sea-level rise and saltwater intrusion are progressively undermining food security and settlement viability; in Vietnam, a 100 cm rise threatens to submerge half the Mekong Delta plain.
Beyond terrestrial inundation, climate change and overfishing are reshaping fish stocks within the South China Sea, a basin responsible for 12 percent of the global catch . Warming ocean temperatures are triggering a poleward migration of species, forcing fishers to travel farther and cross maritime boundaries to follow shifting resources. For many, the choice is to operate without permission in neighbouring Exclusive Economic Zones or abandon their livelihoods entirely. This dynamic increases irregular maritime movement and heightens the risk of conflict, as fishing competition now drives the majority of violent incidents in the region.
Critically, climate-driven mobility blurs the line between survival movement and illegal activity. Lawful artisanal fishers are increasingly misidentified as "illegal" fleets or as part of maritime militias. Such uncoordinated displacement increases the risk of detention, misinterpretation, and humanitarian crises at sea.
Yet, despite these mounting pressures, the phenomenon of climate-driven migration remains largely invisible within regional governance frameworks. This makes ASEAN institutions currently unprepared to manage these slow-onset, maritime-linked movements.
ASEAN’s Governance Gaps in Climate Mobility
The families along the coastlines of Southeast Asia are making quiet choices to leave not because of a single natural disaster, but due to decades-long loss of land, water and income. However, these slow and cumulative migrations remain almost entirely absent from ASEAN’s official policymaking process. ASEAN’s current organisations: the AHA Centre and AWGCC, do not possess the authority to address climate related human mobility. The AHA Centre is primarily focused on responding to sudden disasters leaving slow onset climate displacement outside of coordinated regional response.
ASEAN's main institutional barriers to collective action on human mobility stem directly from the non-interference principle. ASEAN manages skilled mobility within its economic pillars, while climate vulnerable low-skilled workers fall into socio-cultural frameworks that have limited enforcement capabilities. Climate-driven human mobility at sea is also invisible within all of ASEAN's traditional security institutions (i.e., maritime governance platforms), which focus on issues such as territorial disputes and freedom of navigation.
Therefore, in the existing vacuum, displacement is being handled nationally through ad hoc processes. National responses, including Vietnam's coastal relocation programmes, have had challenges in providing long-term livelihood security to displaced populations. Without regional coordination, ASEAN Migration Outlook (2024) warns that climate displacement could generate extreme levels of social, economic, and political instability throughout the region.
Policy Innovation: Integrating Climate Mobility into Maritime Governance
1. Establish an ASEAN Climate Mobility Protocol
ASEAN should develop a formally agreed upon regional instrument under the ASEAN Agreement on Disaster Management and Emergency Response (AADMER), which currently does not explicitly reference climate-induced mobility and evacuation measures. A new protocol could establish protection standards for climate-displaced persons by referencing the African Union Convention for the Protection and Assistance of Internally Displaced Persons in Africa (Kampala Convention). Rather than establishing permanent obligations for resettling displaced populations, the protocol should emphasise providing temporary protections and coordinating assistance to displaced populations and include safeguards to prevent forced returns to environmentally hazardous locations.
2. Expand Maritime Governance to Include Human Security
For displaced communities at sea, the distinction between security risk and survival strategy is often vague. By strengthening the mandate of the AHA Centre and integrating regional disaster data systems, ASEAN could better identify climate-migration hotspots, such as the Mekong Delta and Manila Bay. By incorporating climate mobility into maritime situational awareness, displaced populations would be treated as humanitarian actors, rather than security threats.
3. Identify "Climate Mobility Corridors"
ASEAN can create climate mobility corridors by developing bilateral labour pathways to facilitate safe migration as an adaptation strategy. Climate mobility corridors should be included in the ASEAN Blue Economy Framework to promote the sustainability of marine resources and to define the legal status of migrant fishers. This will allow vulnerable populations to receive resources to either remain in their places of origin or migrate safely to diversify their livelihoods and discourage irregular maritime movement and unregulated fishing. By framing mobility as managed adaptation, movement would shift from being viewed as a measure of failure to being a path to resilience.
4. Develop Access to Finance and Partnerships
ASEAN will need to engage additional multilateral finance and technical partners to fill the funding gap and to collect data on slow-onset events. Without access to predictable financing, adaptation cannot be translated into reliable protections for vulnerable populations. Adaptation-related infrastructure, such as elevated housing or mangrove restoration for coastal defence, should be supported utilising existing financial instruments, including the Green Climate Fund (GCF) and the ASEAN Catalytic Green Finance Facility. ASEAN should also create an ASEAN Climate-Security Data System to reconcile currently unharmonised and aggregated data to provide a single evidence base to monitor cross-border climate mobility and inform policy decisions. This can enhance trust and cooperation among member states while emphasising ASEAN’s central role in addressing non-traditional security concerns in the South China Sea.
Why ASEAN Must Act Now
The existing evidence suggests that climate-induced mobility is no longer a distant projection but an unfolding reality reshaping the South China Sea. Southeast Asia already accounts for a disproportionate share of global disaster-related fatalities, with millions forced to move each year due to floods, storms, and rising sea levels. This growing pattern makes climate change and regional security governance increasingly inseparable. Additionally, the Mekong Delta, Red River Delta, and Manila Bay are not only environmental hotspots; they are emerging mobility frontiers directly linked to maritime stability.
ASEAN’s continued delay in engaging with climate-induced mobility can no longer be treated as a neutral omission. Unmanaged displacement produces strategic ambiguity. As coastlines retreat and marine resources shift, affected populations increasingly move across maritime boundaries in search of survival. In the absence of coordinated regional mechanisms, such movement risks being misinterpreted as territorial probing, illegal encroachment, or geopolitical signalling. In a basin already characterised by fragile trust and contested maritime boundaries, this ambiguity heightens the possibility of escalation.
Integrating climate mobility into maritime governance is therefore not merely a humanitarian consideration, it is a strategic necessity for regional stability. ASEAN’s doctrine of comprehensive security recognises that environmental degradation, economic vulnerability, and social instability are interconnected drivers of insecurity. Climate mobility is at the core of this confluence. Addressing it solely as a welfare issue undermines its transboundary consequences and weakens ASEAN’s ability to manage non-traditional security risks collectively.
Political and economic conditions further reinforce the urgency. Public concern about climate change is high across the region, and evidence consistently shows that proactive adaptation, including managed mobility pathways, is more cost-effective than repeated disaster response. Acting now allows ASEAN to shape climate mobility as structured adaptation rather than respond reactively once instability has taken root.
Conclusion
The South China Sea’s future will be shaped not only by ships and sovereignty claims but also by the movement of people adapting to a changing marine environment. Climate-induced displacement is already altering livelihoods, maritime behaviour, and regional risk dynamics. Integrating climate mobility into ASEAN’s maritime governance offers a pragmatic and forward-looking path. By linking disaster management, marine governance, and labour mobility within existing institutional frameworks, ASEAN can reduce insecurity while remaining consistent with its norms and people-centred vision of security.
This piece was originally written for the Counterpoint Southeast Asia series, published by the Centre on Asia and Globalisation. It received 1st prize in the Counterpoint Southeast Asia Student Competition organised by the Centre on Asia and Globalisation (CAG).