A series of tropical storms and cyclones, intensified by climate change, have caused severe floods across South and Southeast Asia, leaving more than 1,300 dead and displacing millions more.
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In Indonesia’s western-most island of Sumatra, Tropical Cyclone Senyar has caused over 770 deaths as of Thursday with 400 more missing, according to data from the Indonesian National Board for Disaster Management. The government agency said that a total of 3.1 million people have been affected by the storm, which had begun late on the night of 25 November.
According to the Centre of Economic and Law Studies, Sumatra’s economic losses from the floods have cost the island as much as 68.7 trillion rupiah (US$4 billion), nearly 0.3 per cent of Indonesia’s gross domestic product. This includes the costs of flooded palm oil fields as well as damage to infrastructure and real estate.
Southern Thailand and Peninsular Malaysia were also badly affected by Senyar, which had formed in the Strait of Malacca. The southern province of Songkhla, home to the tourist city of Hat Yai, was inundated with floods at least two storeys high in several areas. At least 176 people lost their lives and about a million more were displaced in its wake.
Meanwhile, Malaysian authorities said that at least three people in the country died due to floods caused by the cyclone.
In Sri Lanka, a separate storm, Cyclone Ditwah, left more than 460 dead and hundreds more missing after making landfall last Friday. Although the cyclone has displaced more than 1.1 million people, the country has since reopened its borders to tourists.
Natural phenomena plus climate change
These cases of extreme weather were partly caused by a rare combination of natural phenomena and exacerbated by human-induced climate change.
According to Mariam Zachariah, research associate at Imperial College London’s Centre for Environmental Policy, two climate-related phenomena, the Indian Ocean Dipole (IOD) and La Niña, coincided this year to bring above-average rainfall to South and Southeast Asia.
The IOD refers to changes in sea surface temperatures between the eastern and western parts of the Indian Ocean, whereas the La Niña often brings colder temperatures to the southern hemisphere.
“Alongside these natural drivers, climate change is also likely playing a role, increasing the likelihood and intensity of heavy rainfall, as a warmer atmosphere can hold more moisture,” said Zechariah.
“Warmer sea-surface temperatures have also provided additional energy for forming low-pressure systems and tropical disturbances, contributing to the multiple storms affecting the region.”
David Faranda, research director at the French National Centre for Scientific Research, shared similar insights, highlighting the risks to health and security in Asia.
“Climate change is undeniably fuelling more severe flooding in Southeast Asia,” he said. This is threatening the security of the region’s densely-populated coastal and urban areas, jeopardising food security through crop failures, and threatening already-fragile water management systems, he added.
Adapting to extremes
The latest flood-related disasters in the region follow the destruction caused by typhoons Kalmegi and Fung-wong in the Philippines last month, which swept away villages and displaced thousands.
This was despite the Philippines’ government having allocated billions in funding for flood control projects, exposing corruption risks and the ineffectiveness of reclamation projects versus natural solutions like mangroves, said environmental groups and locals.
But floods are not the only forms of weather-related risks the region is facing – earlier this year, heatwaves … and wildfires killed two dozen people in South Korea, all part of what scientists have described as “climate whiplash”.
Adapting to climate impacts is rising on the agendas of governments across Southeast Asia. Malaysia is planning to publish its National Adaptation Plan (NAP) next year, while Singapore’s Minister of Sustainability and Environment Grace Fu recently announced that the country would complete its NAP over the next five years.
In fact, many of Asia’s developing countries have already submitted their NAPs to the United Nations’ climate change arm, with Indonesia having submitted its own plan last week. The plan said that floods made up the largest proportion of the country’s disasters in 2024 (35 per cent) and together with landslides are the primary cause of economic loss in Java, Sumatra and Sulawesi.
Deforestation worsened Sumatra floods
Indonesia’s NAP also highlighted the importance of “ecosystem restoration as adaptive infrastructure”.
“Forest restoration in uplands mitigates landslides and sedimentation affecting irrigation and hydropower,” said the plan.
However, there was no specific reference to Sumatra, where locals said mass deforestation has made the scale of disaster worse.
“The destructive impact [of Tropical Cyclone Senyar] was greatly exacerbated by the weakened natural defenses in the upper watershed,” said Dr Hatma Suryatmojo, hydrological and watershed conservation researcher at Indonesia’s Universitas Gadjah Madah.
The loss of forest cover resulted in the loss of dense vegetation that absorbed rainwater into the soil, acting as a natural sponge, he added.
A video collated by Indonesian creative agency Sarumpun Studio, which was widely circulated on social media, showed logs of timber spilling into the ocean near Padang, the capital of West Sumatra.
“The majority of river catchment areas on Sumatra Island are in critical condition, enjoying natural forest cover of less than 25 per cent,” said Sapta Ananda Proklamasi, senior researcher at Greenpeace Indonesia. Only 30 per cent of the island’s natural forest remains intact, the organisation said in a statement.
“The Indonesian government must seriously overhaul its overall land and forest governance policies to save nature and the public from climate-driven disasters,” added Greenpeace Indonesia, urging the government to classify the situation as a national emergency so that assistance can be deployed faster.
Indonesia’s environment ministry said that it would investigate the source of the timber, while the country’s president Prabowo Subianto said that the government would intensify efforts to assist affected residents, short of declaring a national emergency.
