With several Asian cities hitting their hottest day on record last month, questions have been raised about the preparedness of one of the world’s most climate-vulnerable regions to climate-induced extreme heat.
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Asia is warming at a faster rate than the global average, according to the World Meteorological Organisation (WMO). In the last month alone, Vientiane (43.2°C) in Laos, Vietnam’s capital of Hanoi (40.4°C) and Metro Manila (38.8°C) in the Philippines all sweltered through their hottest April day in recorded history.
The extended dry spell affected much of South and Southeast Asia in April and May, reaching as far west as Bangladesh and eastern India, and north to southern China, reported WMO secretary-general Celeste Saulo.
Saulo said that “climate change [has] exacerbated the frequency and severity” of prolonged heatwaves in the region, impacting economies and human lives in the process.
Increased heat exposure has already started to impact human health in the region. In Mandalay, central Myanmar, some 50 individuals reportedly died due to heat stress in April alone after the city’s temperature hit 48.2°C. In the Philippines, the Health department has so far documented 77 cases of heat-related illnesses in 2024.
Dr Eleni Myrivili, the United Nations Human Settlements Programme’s first-ever global chief heat officer, described heatwaves as a “silent killer” after being appointed to the post last year.
According to a study by Monash University in Malaysia, annual heat-related mortality in Southeast Asia is projected to increase by 295 per cent by 2030 if no interventions are implemented.
Planning for heat
“Health impacts are the most crucial challenge of the heat action plan,” Dr Upasona Ghosh, assistant professor at the Indian Institute of Public Health in Bhubaneswar, told Eco-Business.
Ghosh is part of the team that drafted heat action plans (HAP) for the city of Bhubaneswar and the state of Odisha.
First adopted in India about a decade ago, HAPs are guidance documents prepared by state, district, and city governments to help them prepare for and respond to the economically damaging and life-threatening impacts of heatwaves.
With South Asia plagued by annual droughts, heat action plans have proven pivotal in reducing the adverse impacts of prolonged dry spells on public health in the region. A key function of HAPs is to direct scarce healthcare, financial, infrastructural and water resources to the most vulnerable people to extreme heat.
Key to the development of a heat action plan is mapping the most vulnerable pockets within a locality and ensuring these people have access to resources to help them manage the heat, explained Ghosh.
Excessive heat during work creates occupational health risks. The International Labour Organisation estimates that economic losses from heat stress-induced productivity declines could reach US$2,400 billion by 2030 – disproportionately affecting low-income and climate-vulnerable countries.
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For decades, the intersection of climate and health has fallen between the cracks of national and intergovernmental processes.
Jess Beagley, policy lead, Global Climate and Health Alliance
Ghosh noted that identifying high-risk sectors and areas within cities allows for targeted interventions to reduce heat exposure and promote adaptive measures. This targeted approach ensures that resources are directed where they are most needed, protecting the most vulnerable populations.
She further noted that strengthening the local health care system is crucial to the implementation of HAPs – highlighting that those most vulnerable to heat stress, such as pregnant women, infants and the elderly, will need special attention on hot days and that developing capacity among healthcare professionals to recognise and respond to heat-related illnesses is necessary.
Indian states work with the National Disaster Management Authority and the India Meteorological Department to develop and enhance heat action plans. India’s Natural Resources Defense Council estimates that there are over 100 existing heat action plans in the country.
Most of Southeast Asia has yet to institutionalise bespoke heat action plans in major cities. To date, Bangkok and Manila are among the few cities in the region to draft measures to deal with extreme heat.
Urban heat island
By 2050, heatwaves will are projected to affect more than 3.5 billion people worldwide – half of them living in urban centres.
The impacts of heatwaves in Southeast Asia’s largest cities are intensified by the urban heat island (UHI) effect – a phenomenon that describes higher temperatures in cities than in rural areas.
Southeast Asia’s rapid rate of urbanisation is exacerbated by limited green public spaces, which in urban settings are 3°C cooler than built-up areas.
The average temperatures of cities in Indonesia, Malaysia and the Philippines can be up to 5.9°C warmer than in rural areas. In Bandung, Indonesia, the heat disparity between urban and rural neighbourhoods is 7°C.
“The construction of more paved areas, particularly roads and parking lots, encourages more vehicles that burn more fossil fuels and worsen air quality,” explained Vic Dul-loog and Zenaida Galingan, professors at the University of the Philippines Diliman College of Architecture.
“The erection of more buildings will add to the thermal gain in urban areas. The need to power up these new structures will require additional amounts of fossil fuel to be burned,” according to their study, Urban Heat Island Phenomenon A Look into the Metro Manila Setting.
In Phnom Penh, Cambodia, the UHI effect already contributes to up to 25 additional very hot days a year in the city’s central districts. By 2050, the number of very hot days a year is projected to more than double for neighbourhoods that have the strongest UHI effects.
According to a World Bank report, more than 100,000 people in the Asia and Pacific region are projected to die each year from extreme heat without climate-related interventions.
“Man created the urban heat island effect. Man must undo it in order to survive and achieve more livable and energy-efficient cities,” concluded Dul-loog and Galingan.
As member states of the World Health Organization (WHO) convene in Geneva this week for the 77th World Health Assembly, the Global Climate and Health Alliance is lobbying for the adoption of a resolution on climate change and health.
“Climate change is shaping people’s health, from increasing food insecurity and air pollution to more frequent extreme heat and weather events”, said Rosie Tasker, clean air liaison at the Global Climate and Health Alliance in a statement.
“For decades, the intersection of climate and health has fallen between the cracks of national and intergovernmental processes. With the UNFCCC intersessional climate meetings in Bonn around the corner, and the COP29 international climate negotiations on the horizon, it’s crucial that the health and climate community maintains and builds on this momentum,” said Global Climate and Health Alliance policy lead Jess Beagley.
