Climate Change Linked to Deadly Floods Across Asia, Study Finds

Ocean temperatures warmed by human-caused climate change intensified the rainfall that triggered deadly floods and landslides across Southeast Asia in recent weeks, according to a newly released analysis.

The study by World Weather Attribution (WWA) examined heavy rainfall from cyclones Senyar and Ditwah, which devastated parts of Malaysia, Thailand, Indonesia and Sri Lanka starting in late November. Researchers found that warmer sea surface temperatures in the North Indian Ocean significantly amplified these weather systems, providing additional heat and moisture that fed the storms.

The human toll has been catastrophic. More than 1,600 people have died in floods and landslides triggered by these cyclones, with hundreds still missing. The disasters are part of a larger pattern of deadly weather events affecting Southeast Asia throughout the year.

“It rains a lot here but never like this,” said Shanmugavadivu Arunachalam, a 59-year-old schoolteacher in Hatton, Sri Lanka. “Usually, rain stops around September, but this year it has been really bad. Every region of Sri Lanka has been affected, and our region has been the worst impacted.”

The WWA analysis revealed that sea surface temperatures over the North Indian Ocean were 0.2 degrees Celsius higher than the average over the past three decades. More significantly, without global warming, these ocean temperatures would have been approximately 1 degree Celsius cooler than they were during the cyclones.

This warming directly impacts storm systems. “When the atmosphere warms, it can hold more moisture. As a result, it rains more in a warmer atmosphere as compared to a world without climate change,” explained Mariam Zachariah, a researcher at the Centre for Environmental Policy at Imperial College London and one of the report’s authors.

The current global temperature is now 1.3 degrees Celsius warmer than pre-industrial levels of the 19th century, according to the National Oceanic and Atmospheric Administration. This worldwide heating is creating conditions where weather disasters become more frequent and severe.

World Weather Attribution, a collaboration of climate scientists, employs peer-reviewed methodologies to rapidly assess the connection between extreme weather events and climate change. While their analyses are published quickly to inform public discussion, they follow rigorous scientific protocols.

“Anytime we decide to do a study, we know what is the procedure that we have to follow,” said Zachariah. The team reviews findings internally and submits portions of their analysis for peer review, even after preliminary versions are made public.

Unlike some of their previous studies, researchers could not provide precise probabilities of how much climate change worsened these specific storms due to limitations in climate models for the affected island regions. However, the connection to warmer ocean temperatures was clear.

The impact across the region has been devastating. Indonesia’s Aceh province experienced widespread destruction, with flash floods sweeping away homes and vehicles. In Sri Lanka’s mountainous central regions, landslides buried entire communities, with survivors left searching through debris for belongings.

“Global warming is a powerful amplifier to the deadly floods, typhoons and landslides that have ravaged Asia this year,” said Jemilah Mahmood from the Sunway Centre for Planetary Health, a Malaysia-based think tank not involved in the study. “The region and the world have been on this path because, for decades, economic development was prioritized over climate stability. It’s created an accumulated planetary debt, and this has resulted in the crisis we face.”

The analysis identified multiple factors increasing vulnerability, including rapid urbanization, high population density, and infrastructure built in low-lying flood plains. These development patterns have elevated exposure to flood events across the region.

“The human toll from cyclones Ditwah and Senyar is staggering,” said Maja Vahlberg, a technical adviser with the Red Cross Red Crescent Climate Centre. “Unfortunately, it is the most vulnerable people who experience the worst impacts and have the longest road to recovery.”

As recovery efforts continue across the affected countries, the study highlights how climate change is already transforming weather patterns in ways that threaten millions of lives across Southeast Asia.