Ocean Warmed by Climate Change Fed Intense Rainfall, Deadly Floods in Asia, WWA Study Finds

BENGALURU, India (AP) — Ocean temperatures warmed by human-caused climate change fed the intense rainfall that triggered deadly floods and landslides across Asia in recent weeks, concludes a rapid analysis by World Weather Attribution released Wednesday.

The study focused on heavy rainfall from cyclones Senyar and Ditwah in Malaysia, Thailand, Indonesia, and Sri Lanka starting late last month. It found that warmer sea surface temperatures over the North Indian Ocean added energy to the cyclones.

Floods and landslides triggered by the storms have killed more than 1,600 people, with hundreds more still missing. The cyclones are the latest in a series of deadly weather disasters affecting Southeast Asia this year, resulting in loss of life and property damage.

“It rains a lot here but never like this,” said Shanmugavadivu Arunachalam, a 59-year-old schoolteacher in the mountain town of Hatton in Sri Lanka’s Central Province. “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.”

Warmer Sea Surface Temperatures

Without global warming, sea surface temperatures over the North Indian Ocean would have been about 1°C/1.8°F older than they were, according to the analysis. Compared to the average over the past three decades, they were 0.2°C/0.36°F higher. The warmer ocean temperatures added heat and moisture that supercharged the storms.

Overall, the average global warming is currently about 1.3°C warmer than pre-industrial times in the 19th century, according to the U.S. National Oceanic and Atmospheric Administration.

“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,” said report co-author Mariam Zachariah, a researcher at the Centre for Environmental Policy at Imperial College London.

Measuring Climate Impacts Quickly

World Weather Attribution uses peer-reviewed methods to conduct rapid studies examining how extreme weather events are linked to climate change.

“Anytime we decide to do a study, we know what is the procedure that we have to follow,” Zachariah explained, adding that that process includes external peer review, even after an early version of a study is made public.

The rapid release of WWA analysis helps inform the general public about the impacts of climate change, she said.

“We want people everywhere to know about why something happened in their neighbourhood,” Zachariah told The Associated Press. “But also be aware about the reasons behind some of the events unfurling across the world.”

The WWA often estimates how much worse climate change made a disaster using specific probabilities. In this case, though, the researchers said they could not estimate the precise contribution of climate change to the storms and ensuing heavy rains because of limitations in climate models for the affected islands.

But “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.”

Climate Change a ‘Powerful Amplifier’

Global warming is a “powerful amplifier” to the deadly floods, typhoons, and landslides that have ravaged Asia this year, said Jemilah Mahmood, executive director of the Sunway Centre for Planetary Health, a Malaysia-based think tank that was not involved with the WWA analysis.

“The region and the world have been on this path because, for decades, economic development was prioritized over climate stability,” Mahmood said. “It’s created an accumulated planetary debt, and this has resulted in the crisis we face.”

The analysis found that across the affected countries, rapid urbanization, high population density, and infrastructure in low-lying flood plains have elevated exposure to flood events.

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