The reasons behind the high number of deaths in floods across Southeast Asia – and why it should be a wake-up call

Over 1,300 lives were lost last month as a series of cyclonic storms and floods ravaged countries across Southeast Asia. Experts attribute the disasters to severe weather intensified by human activity. Indonesia reported more than 750 fatalities, Sri Lanka around 400, Thailand approximately 200, and Malaysia confirmed three deaths. Over 800 people remain missing. Millions have been affected, with entire villages cut off after the destruction of roads, bridges, and power lines, forcing tens of thousands into emergency shelters.

Scientists warn that such extreme events, once considered unusual, are becoming the new norm. The region was hit by three cyclonic storms in rapid succession: Typhoon Koto (also called Verbena) moved from the Philippines toward Vietnam starting November 23; Cyclone Senyar, a rare storm in the Strait of Malacca, impacted Indonesia, Malaysia, and southern Thailand; and Tropical Cyclone Ditwah struck Sri Lanka before brushing Indias southeast coast.

Meteorologist Mahesh Palawat explains that unusually warm seas fueled rapid storm formation. The southern Bay of Bengal saw temperatures of 2930C, providing extra energy for cyclones. Higher ocean temperatures strengthen storms and increase rainfall, while rising sea levels amplify storm surges. Normally, tropical storms are separated by 1520 days, allowing energy to dissipate, but this time, storms followed each other unusually quickly.

Farwiza Farhan from Forest, Nature & Environment Aceh (HAkA) emphasizes that human actions worsened the impact. Illegal logging and unauthorized land clearing in the Leuser Ecosystem removed natural buffers, so heavy rains turned into deadly floods, destroying communities downstream.

In Indonesia, heavy rains hit Sumatra on November 26, triggering floods and landslides that submerged towns, uprooted homes, and damaged infrastructure. Nearly 300,000 people were displaced in North Sumatra, West Sumatra, and Aceh, with rescue operations relying on helicopters and boats. Satellite imagery shows entire valleys clogged with mud, boulders, and fallen trees.

Analysts describe the disasters as compound events, where multiple hazards strike vulnerable areas in rapid succession. Matt Sechovsky from BMI highlights that climate change and human activities, such as deforestation, unregulated housing, and poorly planned infrastructure, intensified the destruction.

Sri Lanka suffered particularly from Cyclone Ditwah, which caused landslides in the central highlands and widespread flooding. About a third of the population temporarily lost electricity or water, with more than 80,000 people displaced and nearly 120,000 housed in government shelters. The president declared a state of emergency and appealed for international assistance.

Local activists note that the true toll may be higher than reported. Collapsed communication and power lines left many communities isolated, with shortages of food and essential services. Decades of deforestation and large-scale development on steep terrain made landslides more severe, particularly for vulnerable workers living in unstable housing.

Scientists explain that warmer air holds more moisture, increasing rainfall intensity, while hotter oceans energize cyclones. Experts warn that without rapid reductions in fossil-fuel emissions and investments in resiliencesuch as restoring forests and wetlands, enforcing planning regulations, and improving early-warning systemssuch catastrophic events may become increasingly frequent.

Author: Ethan Caldwell