KATHMANDU: Warmer seas and heavier rainfall linked to climate change, combined with the unique geographies of Indonesia and Sri Lanka, intensified the catastrophic floods that killed more than 1,600 people last month, according to a group of international scientists.
Two tropical storms brought record-breaking rain to the countries, triggering landslides and severe flooding that left over 600 dead in Sri Lanka and nearly 1,000 in Indonesia.
A rapid attribution analysis conducted by global climate scientists found that a combination of factors—including elevated sea surface temperatures, intensified rainfall driven by climate change, and regional weather patterns such as La Niña and the Indian Ocean Dipole—contributed to the disaster.
Although the researchers could not determine the exact proportion of the floods directly attributable to climate change due to model limitations, they confirmed a clear intensification of heavy rainfall events in both regions over recent decades.
“Climate change is at least one contributing driver of the observed increase in extreme rainfall,” said Mariam Zachariah, a research associate at Imperial College London and one of the study’s authors.
The study found extreme rainfall events in the Malacca Strait region between Malaysia and Indonesia have increased by an estimated 9 to 50 percent due to rising global temperatures.
“In Sri Lanka, the trends are even stronger,” Zachariah said, noting that heavy rainfall events are now 28 to 160 percent more intense than in the past.
Despite a wide variation in datasets, scientists said all indicators point in the same direction: extreme rainfall is becoming more intense.
Other factors, including widespread deforestation and natural landscapes that funneled torrential rains into densely populated floodplains, further amplified the devastation.
The storms struck during Asia’s monsoon season, which typically brings some level of flooding. However, the scale of destruction in Sri Lanka and Indonesia was described as “virtually unprecedented.”
“Monsoon rains are normal in this part of the world,” said Sarah Kew, climate researcher at the Royal Netherlands Meteorological Institute and the study’s lead author. “What is not normal is the growing intensity of these storms and how they are affecting millions of people and claiming hundreds of lives.”
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