A Warming World: Understanding Climate Change and Health in Southeast Asia

Climate change is a defining global challenge, and its impacts are accelerating across Southeast Asia. The region is already experiencing rising temperatures, sea-level rise, extreme weather events, droughts, floods, and ecosystem disruption. According to the Planetary Security Initiative (2024), Southeast Asia has already warmed by 0.5°C since 1980, with temperatures projected to rise by 1.1°C to 3.5°C by the 2050s, depending on emission levels. At the same time, sea levels in the region are expected to rise by 0.2–0.3 meters. The report also projects more intense heatwaves and shifting rainfall patterns, bringing heavier rains to some areas and prolonged dry spells to others, posing serious risks to health, ecosystems, and livelihoods. 

These escalating climate pressures are not only environmental, but they are also deeply human. They threaten food and water security, force population displacement, and strain already vulnerable public health systems across the region. 

The health consequences of climate change are increasingly visible. Southeast Asia is already experiencing rising rates of heat-related illnesses, outbreaks of vector-borne diseases like dengue cases, food insecurity, and respiratory problems linked to air pollution and haze. Vulnerable populations, including youth, women, Indigenous peoples, and disaster-affected communities, face disproportionate risks and often have limited access to adequate healthcare and support. 

Despite growing recognition of the challenges at the intersection of climate and health, the climate–health nexus remains significantly underfunded and under-researched. According to the 2021 WHO Health and Climate Change Survey Report, over 70% of countries identified insufficient financing as a major barrier to implementing their national health and climate strategies. This gap is especially pronounced in Southeast Asia, where most countries are low- and middle-income (LMICs) and face heightened vulnerability to climate-related health risks and shocks. Moreover, research on climate and health has historically been centered on high-income countries, rather than on LMICs where the impacts of climate change are most severe and urgent (Ryder, 2024).

Despite the growing urgency responding to environmental hazard and emerging threats of climate-related threats, there remains a significant gap in understanding how these dynamics affects population health, health system performance, and community vulnerability across Southeast Asia. Expanding high-quality, locally led research, including discovery, applied, and translational studies, can generate the context-specific evidence needed to inform policy, guide adaptation strategies, and support interventions that protect the most at-risk populations. Such efforts are critical to developing resilient, equitable, and responsive health systems capable of managing the accelerating health impacts of a changing climate. 

This article explores major climate-related health impacts in Southeast Asia, focusing on heat stress and mortality, food insecurity, vector-borne diseases, and air pollution and respiratory health.

Heat Stress and Mortality: Rising Temperatures and Climate-Driven Health Burdens in Southeast Asia.

Rising temperatures, amplified by urban heat islands, unsafe working conditions, and inadequate housing, are contributing to a surge in heat-related illnesses and deaths across Southeast Asia. Vulnerable groups such as older adults, outdoor workers, children, and residents of informal settlements face the highest risks. 

According to a 2025 report by Asia News Network, Southeast Asia experienced extreme heat events in the early months of the year, with significant health and agricultural consequences. Similarly, the World Meteorological Organization reports that Asia is warming at roughly twice the global rate, with 2024 among the warmest years on record and widespread heat affecting the region (Siddeeq, 2025). In Brunei, daily maximum temperatures reached 39.2°C in July 2025, setting a new national record, compared with typical daily maxima of 31–33°C. (Masters & Henson, 2025; Weatherspark, n.d.) By April, Cambodia and Myanmar recorded temperatures exceeding 40°C, subjecting communities to searing heat and oppressive humidity (Asia News Network, 2025). The report also noted that a May heatwave in Laos severely impacted agricultural production, particularly climate-sensitive crops such as coffee and vegetables. 

The Asia News Network (2025) documented severe health impacts across Southeast Asia, likely worsened by prolonged heat, a multi-country study found that urban areas in Southeast Asia experienced average warm-season temperatures of 29.13°C, with approximately seven heat-related deaths per day per city, one of the highest regional mortality burdens globally (Choi et al., 2022). However, these modelled estimates cannot be directly compared with national reporting figures due to major differences in methodology, data availability, and surveillance systems.

At the country level, the health toll is increasingly evident. In Indonesia, over 35,500 dengue fever cases and 290 deaths were reported between January and March. In Thailand, data from the past six years (2019–2024) recorded a cumulative total of 212 heat-related fatalities, averaging 27 deaths per year (Global Heat Health Information Network, 2025). Malaysia reported 45 heat-related illnesses from January to mid-April 2025, including two deaths, one involving a three-year-old child, while the Philippines recorded 77 heat-related illnesses and at least seven deaths between January 1 and April 29, 2025. These national figures appear far lower than modelled estimates, but they reflect substantial underreporting and inconsistent classification of heat-related mortality.These figures may underestimate the true burden due to underreporting and indirect causes (Chin & Begum, 2025), and the lack of standardized, long-term datasets on heat-related mortality further obscures the scale of the problem.

 Research gaps remain a pressing concern. Li, Yuan, and Hang (2022) highlight that Southeast Asia, a climatologically significant region with limited data, faces a critical shortage of research on heatwaves. While these numbers may not yet represent the highest burden on population health, rising temperatures, more frequent and intense heatwaves, and an aging population highlight the need for early interventions to prevent this from becoming a larger public health issue. 

Climate change is already having significant and measurable effects on human health in Southeast Asia. Extreme weather events such as prolonged heatwaves, storms, and floods cause immediate injuries, illnesses, and fatalities (WHO, 2025). Beyond these acute impacts, climate change also affects health indirectly by altering the fundamental pillars of life: air, water, and food, which are essential for human well-being (WHO, 2025). 

These changes are increasingly reflected in heat-related mortality trends across the region.The consequences are already visible in mortality and disease patterns. The World Health Report (2002) estimated that approximately 82,000 people in Southeast Asia died in 2000 due to climate change and its effects, the highest number among all WHO regions. While older estimates highlight the scale of climate-related mortality, more recent evidence points to rising risks associated specifically with extreme heat, underscoring heat stress as a growing and under-recognized public health threat.

Between 2000 and 2019, three of the ten most climate-affected countries were in Southeast Asia (HCWH, n.d.). This exposure translates into heightened risks of undernutrition, excess morbidity and mortality, respiratory diseases such as asthma and tuberculosis, cardiovascular conditions including myocardial infarction and stroke, and a range of cancers. Vulnerable populations also face additional burdens, including displacement and reduced access to reproductive and other essential health services (HCWH, n.d.).

Food Security: Climate change is weakening food systems in Southeast Asia, increasing hunger and nutrition insecurity.

Climate change is significantly undermining food systems across Southeast Asia, with far-reaching consequences for nutrition and livelihoods. Impacts such as crop loss, declining fish stocks, and freshwater scarcity are driving food insecurity and contributing to undernutrition, particularly among rural, coastal, and low-income populations. By 2020, approximately 7.3% of the region’s population was undernourished, while 18.8% faced moderate to severe food insecurity (Chiengkul, 2022).

Agricultural output, including staple crops like rice and fishery resources, remains highly vulnerable to extreme weather events and shifting climate patterns. The 2016 ASEAN Regional Report on Nutrition Security highlighted that an alarming proportion of children, adolescents, and adults in the region suffer from malnutrition and consume poor-quality diets. Climate factors such as rising temperatures, extreme rainfall, and floods are projected to reduce rice yields by 3–10%, with Cambodia, Myanmar, and Vietnam expected to be most affected. These changes will also disrupt labor capacity, lower agricultural productivity, and cause greater food price volatility, all of which exacerbate food insecurity, especially among vulnerable low-income communities.

Although aquaculture has expanded rapidly as a critical food source, climate-related threats such as storm surges and rising sea temperatures could render up to 30% of aquaculture areas unsuitable by 2050–2070 (Planetary Security Initiative, 2024), further challenging food security and nutrition in the region. Together, these interconnected health challenges highlight the urgency of adopting a Planetary Health approach. PlanetrayHealth is a holistic approach that acknowledges the interconnectedness of human, animal, and environmental health. In Southeast Asia, where ecosystems are diverse and human activities closely interact with animals and natural environments, this interdependence is especially significant. Environmental changes, land-use shifts, and climate variability impact the health of people, animals, and ecosystems in complex and intertwined ways. 

Addressing health challenges in this region requires collaborative efforts across sectors, including public health, veterinary science, agriculture, and environmental management, to develop integrated strategies that promote the health of all living beings and the environments they inhabit. Strengthening surveillance systems, enhancing cross-sector collaboration, and improving adaptive risk management can inform coordinated interventions that promote sustainable, resilient health outcomes for communities, ecosystems, and food systems throughout Southeast Asia.

Vector-Borne Diseases and Food Insecurity: Climate change is intensifying mosquito-borne diseases across Southeast Asia, heightening outbreak risks.

Climate change is reshaping the landscape of vector-borne diseases in South and Southeast Asia. Warmer temperatures and shifting rainfall patterns are expanding the geographic range, intensity, and seasonality of mosquito-borne illnesses such as dengue, malaria, and chikungunya, placing growing pressure on already strained health systems. 

Research has established strong links between climate variability, particularly rising temperature and altered rainfall, and the rise in vector-borne disease outbreaks in the region (Servadio et al., 2018). These climate conditions create more favorable environments for mosquito breeding and virus transmission. More broadly, over 50 percent of known human pathogens are projected to be amplified by climate change, disproportionately affecting Southeast Asia. This includes waterborne, vector-borne, and zoonotic diseases that are already widespread in the region (Mora et al., 2022). 

In early 2024, Southeast Asia experienced a surge in dengue cases. Indonesia alone reported over 88,000 confirmed cases and 621 deaths by the end of April, three times higher than during the same period in 2023. Other countries, including Thailand, Bangladesh, and Nepal, also saw significant increases. Case fatality rates varied from up to 1.09% in Bangladesh, though cross-country comparisons are limited by differences in surveillance and case definitions (World Health Organization, 2024). Beyond infectious disease, climate change is also contributing to intersecting risks that affect broader health and livelihood outcomes.

Air Pollution and Respiratory Health: Worsening environmental conditions are increasing respiratory illness and mortality across Southeast Asia. 

Transboundary haze, forest fires, and emissions from transport and industry are significantly worsening air quality across Southeast Asia. This pollution surge increases both the incidence and severity of respiratory conditions such as asthma, bronchitis, and chronic obstructive pulmonary disease (COPD), with children and the elderly being particularly vulnerable.

Forest and peatland fires, mostly caused by slash-and-burn agricultural practices, generate thick haze that drifts over large parts of the region. This smoke contributes to 40–60% of the haze seen in major Southeast Asian cities, significantly degrading air quality by releasing harmful fine particles known as PM₂.₅ (Health Care Climate Action, 2022). These tiny particles penetrate deep into the lungs, exacerbating respiratory diseases and other health problems. 

In 2021, air pollution accounted for approximately 630,000 deaths in Southeast Asia, ranking as the leading cause of mortality in countries such as Cambodia, Lao PDR, and Myanmar (Health Effects Institute, 2025). 

Environmental health focuses on assessing and managing environmental factors that influence human well-being. Globally, nearly one-quarter of all deaths are linked to environmental causes. In Southeast Asia alone, an estimated 3.8 million lives could be saved by addressing environmental risks present in homes, workplaces, and communities (World Health Organization, 2025). These risks encompass air pollution, inadequate water and sanitation, chemical exposures, radiation, community noise, occupational hazards, agricultural practices, the built environment, and climate change.

Rapid urbanization, industrialization, and environmental degradation have intensified exposure to pollutants, unsafe water sources, and deteriorating air quality across the region. Vulnerable populations, particularly children, bear a disproportionate share of these hazards.

Worsening environmental conditions underscore the need for research that examines how air and water pollution, chemical exposures, and urban environmental stressors shape health outcomes across the region. Advancing innovative solutions, such as cleaner technologies, climate-resilient urban design, and improved waste and emissions management, can enhance environmental quality, promote sustainable urban development, and reduce community-level exposure to environmental hazards. Together, these efforts support more equitable health outcomes across diverse populations. 

In Southeast Asia, these environmental and climate pressures fall most heavily on vulnerable groups, including small-scale and marginal farmers reliant on rain-fed agriculture, the rural poor, urban slum residents, mountain communities, small-island populations, and coastal populations. Their vulnerability is compounded by high burdens of climate-sensitive diseases, particularly malnutrition, vector-borne illnesses, and diarrheal diseases (WHO, 2025). 

Addressing these intersecting risks requires more targeted research that documents climate-related health impacts, evaluates vulnerability across different populations, and identifies effective early-warning and risk-reduction strategies. Strengthening the evidence base on heat stress, mortality, and climate-sensitive diseases can support policies and interventions that enhance community resilience and protect those most at risk in a warming world.

 

References: 

ASEAN & UNICEF. (2016). Regional report on nutrition security in ASEAN, Volume 1. ASEAN Secretariat. https://www.asean.org/wp-content/uploads/2016/03/Regional-Report-on-Nutrition-Security-in-ASEAN-Volume-1.pdf 

Chiengkul, P. (2022, August 11). Hunger, malnutrition and climate change: Challenges facing Southeast Asia. Fulcrum. https://fulcrum.sg/hunger-malnutrition-and-climate-change-challenges-facing-southeast-asia/ 

Chin, H. S., & Begum, S. B. (2025, January 10). Degrees of danger: Beating the heat in Southeast Asia. Asia News Network. https://asianews.network/degrees-of-danger-beating-the-heat-in-southeast-asia 

Choi, H. M., Lee, W., Roye, D., Heo, S., Urban, A., Entezari, A., et al. (2022). Effect modification of greenness on the association between heat and mortality: A multi-city multi-country study. EBioMedicine, 84, 104251.https://doi.org/10.1016/j.ebiom.2022.104251

Global Heat Health Information Network. (2025, September 12). Extreme heat takes toll on South and Southeast Asia. https://heathealth.info/news/extreme-heat-takes-toll-on-south-and-southeast-asia/

Health Care Climate Action. (2022, September). RX Clean Air – Southeast Asia: A dossier on air pollution for health professionals in the Southeast Asian region. Health Care Climate Action. https://healthcareclimateaction.org/sites/default/files/2022-09/RX%20Clean%20Air%20-%20Southeast%20Asia.pdf 

Health Care Without Harm. (n.d.). Rise of the South-East Asia Alliance on Health and Climate. https://asia.noharm.org/rise-south-east-asia-alliance-health-and-climate 

Health Effects Institute. (2025, January 23). New State of Global Air Asia regional report details latest data on air quality and health impacts in Central, South and Southeast Asia. https://www.healtheffects.org/announcements/new-state-global-air-asia-regional-report-details-latest-data-air-quality-and-health 

Li, X.-X., Yuan, C., & Hang, J. (2022). Heat wave trends in Southeast Asia: Comparison of results from observation and reanalysis data. Geophysical Research Letters, 49(3), e2021GL097151. https://doi.org/10.1029/2021GL097151 

Masters, J., & Henson, B. (2025, August 12). July keeps the torrid pace going in one of Earth’s hottest years on record. Yale Climate Connections. https://yaleclimateconnections.org/2025/08/july-keeps-the-torrid-pace-going-in-one-of-earths-hottest-years-on-record/ 

Mora, C., McKenzie, T., Gaw, I. M., Dean, J. M., von Hammerstein, H., Knudson, T. A., Setter, R. O., Smith, C. Z., Webster, K. M., Patz, J. A., & Franklin, E. C. (2022). Over half of known human pathogenic diseases can be aggravated by climate change. Nature Climate Change, 12(8), 869–875. https://doi.org/10.1038/s41558-022-01426-1 

Planetary Security Initiative. (2024, December). Climate risk report for the Southeast Asia region. https://www.planetarysecurityinitiative.org/news/climate-risk-report-southeast-asia-region 

Ryder, B. (2024, February 22). Making the health impacts of climate change visible. Wellcome. https://wellcome.org/news/making-health-impacts-climate-change-visible 

Sa-ngamuang, C., Lawpoolsri, S., Su Yin, M., Barkowsky, T., Cui, L., Prachumsri, J., & Haddawy, P. (2023). Assessment of malaria risk in Southeast Asia: A systematic review. Malaria Journal, 22(339). https://doi.org/10.1186/s12936-023-04772-3 

Servadio, J. L., Rosenthal, S. R., Carlson, L., & Bauer, C. (2018). Climate patterns and mosquito-borne disease outbreaks in South and Southeast Asia. Journal of Infection and Public Health, 11(4), 566–571. https://doi.org/10.1016/j.jiph.2017.12.006 

Siddeeq, S. (2025, September 8). Global warming in Asia region is heating twice as fast. Climate Impacts Tracker. https://www.climateimpactstracker.com/global-warming-in-asia-region-is-heating-twice-as-fast/ 

Weatherspark. (n.d.). Average weather in Brunei year-round. https://weatherspark.com/y/150206/Average-Weather-in-Brunei-Year-Round#Figures-Temperature 

World Health Organization. (2021, November 8). 2021 WHO health and climate change global survey report: Tracking global progress (ISBN 978‑92‑4‑003850‑9). World Health Organization. https://www.who.int/publications/i/item/9789240038509 

World Health Organization. (2024). Disease Outbreak News – Dengue in Southeast Asia. https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON518 

World Health Organization. (n.d.). Climate change in the South‑East Asia Region. WHO Regional Office for South‑East Asia. Retrieved July 17, 2025, from https://www.who.int/southeastasia/health-topics/climate-change 

World Health Organization. (2025, May 5). Air pollution and health in Southeast Asia: Regional overview. https://www.who.int/publications/i/item/sea-eh-586