In Sumatra, deforestation is being linked to the deadly toll of recent flash floods after a huge number of logs washed up downstream. Survivors like this woman in Karang Baru, Aceh province, had to scramble for over an hour across logs to get aid. — Reuters
In November 2025, torrential rain unleashed devastating scenes across South and South-East Asia – roads became raging rivers, floodwaters rose as high as 2m, and landslides dumped torrents of mud and debris on villages, cutting off communities from food or aid.
Satellite images showed shocking destruction reminiscent of the 2004 Asian tsunami. In Aceh province, Sumatra, mud turned a vast coastal area khaki-brown while mountainsides bore large landslide scars. In Sri Lanka, roads and fields near Colombo’s Kelani River became muddy ponds.
By early December, 2025, the overall toll was staggering: 1,600 people dead, 11 million people affected, and 1.2 million forced from their homes, the United Nations reported.
Heavy monsoon rain is not news, but this season was one of the wettest in recent memory. This was “unusual” and “extreme” – the same words heard about recent heatwaves.
Why should we be surprised? The climate crisis is intensifying – 2024 broke heat records set in 2023, and the last decade (2015-2024) was the warmest recorded. Year after year, we see more extremes. Yet we’re still not taking adequate action. As storms began lashing the region, the UN climate change conference (COP 30) closed, making only limp progress.
It is alarming to see ordinary weather phenomena become extraordinary. The recent storms were linked to intensified monsoons, cyclones, and the La Niña weather cycle. We need to recognise the drivers behind this extreme weather and their link to climate change.
> Extreme rainfall: The sheer volume of rainfall was unprecedented. Many records were broken, 14 in Vietnam alone. The 1,740mm of rain in 24 hours in Hué broke the city, country, and continent record, and was the second-highest known globally.
Scientists have long warned that a warmer planet intensifies tropical storms. Warmer air holds more moisture, leading to more rainfall. So even moderate cyclones produce extreme rainfall.
> Warmer seas: Seas are warming faster in this region, which fuels cyclones. Typhoon formation and extreme weather are heavily influenced by sea surface temperatures, says Emeritus Prof Fredolin Tangang, a climatologist with Universiti Kebangsaan Malaysia.
The 2025 typhoon season was dramatic, with two super typhoons and repeated hits on the Philippines and Vietnam. The Asia-Pacific region faces the world’s “most intense and frequent tropical cyclone activity”, the World Meteorological Organisation says.
> Unique phenomena: We saw rare events, with a cyclone forming near Peninsular Malaysia and three tropical storms occurring simultaneously: Typhoon Koto, near the Philippines and Vietnam; Cyclone Senyar, which hit Sumatra and Malaysia; and Cyclone Ditwah, near Sri Lanka. (Typhoons and cyclones are similar storms, named differently by location.)
“I realised that this was extraordinary, perhaps unprecedented,” says Prof Tangang.
Cyclones rarely form (or land) near the equator, as the Coriolis force, which imparts spin, is weak here. Senyar was the first cyclone known to form in the Straits of Malacca and the second to strike the peninsula. Fortunately, notes Prof Tangang, its impact here was less severe than in Sumatra.
He adds that this extreme weather was not an isolated occurrence. “It could well become the norm in the future if the world fails to address climate change.”
This highlights the need for the region to strengthen preparedness with early warning systems and proactive responses. Malaysia did well in its response, acting quickly to warn, and evacuating 25,000 people to relief centres. As a result, only three deaths were reported. Conversely, in Hat Yai, Thailand, where 145 people died, a lack of coordination and confusion marred the response.
Climate adaptation must also be accelerated. Yesterday’s infrastructure and drainage are inadequate for tomorrow’s weather. Land use planning is critical here to mitigate disasters. Urbanisation and development in floodplains reduce water absorption in the landscape, escalating flood risks. By contrast, forests offer hydrological services, acting as a sponge to absorb water and limit runoff.
Human actions are often the drivers that turn natural hazards into devastating disasters. When forests are razed from steep slopes, a landslide afterwards is hardly a “natural” disaster. Blaming nature just evades accountability.
In Sumatra, deforestation is being linked to the deadly toll. A huge number of logs washed up downstream and some crashed into homes. Survivors in Aceh Tamiang had to scramble over logs for an hour to get aid, Reuters reported. Images circulating online prompted authorities to try to trace the logs.
Eight companies, and reports of illegal logging, are being investigated.
Forest loss has been severe in Sumatra, with an area the size of Switzerland (over four million hectares) cleared since 2001. This prompted researchers Muham-mad Irfansyah Lubis and Prof Janice Lee from Singapore’s Nanyang Technological University to study the impact on flooding last year.
They found that flood risks increased with reduced tree cover and expansion of oil palm plantations, underscoring the vital role of forests in regulating water flow, and the need for policymakers to consider these benefits when making decisions on land use.
We cannot simply shrug off these storms as “unusual” weather. This is a preview, the new normal. We should heed the lessons here in the value of preparedness and preserving forests, and the need for greater ecological responsibility. Otherwise, future tragedies are inevitable.
