Climate change turbocharged the winds and rain of Typhoon Gaemi, which killed dozens of people across the Philippines and China earlier this year, a group of scientists said on Thursday.
World Weather Attribution (WWA), a network of scientists who have pioneered peer-reviewed methods for assessing the role of climate change in extreme events, looked at three regions worst affected by the typhoon: the northern Philippines, China's Taiwan region and Hunan Province.
It found the system's wind speeds were seven percent more intense due to man-made climate change, and its rainfall was 14 percent heavier in Taiwan and nine percent heavier in Hunan.
The study could not draw definitive conclusions about the role of climate change on the rainfall in the Philippines because of the region's complex monsoon rain patterns.
Still, they found the warm seas that helped form and fuel Typhoon Gaemi "would have been virtually impossible" in a world that had not warmed to the current 1.2 degrees Celsius above pre-industrial levels.
The group's modeling also found that this warming has already increased the number of similarly strong storms by 30 percent, up from around five a year to six or seven.
Typhoon Gaemi brought extreme rainfall to Chaozhou City, south China's Guangdong Province. /CFP
"This study confirms what we've expected – hotter seas and atmospheres are giving rise to more powerful, longer-lived and deadlier typhoons," said Ralf Toumi, director of the Grantham Institute-Climate Change and the Environment, at Imperial College London.
Teasing out the impact of climate change on tropical cyclones is complicated, but scientists are focusing more work on these weather systems.
WWA's method involves assessing how unusual an extreme event is, then modeling the likelihood of a similar event and its intensity in two scenarios: today's world and one without current levels of warming.
The scientists used that method with a new approach developed by Imperial College London tailored specifically to tropical storms.
It uses computer modeling to overcome the relative lack of historical data on tropical cyclones.
While the Asia-Pacific region has long dealt with typhoons, the scientists warned that their work highlighted "gaps in typhoon preparedness and the massive impacts caused by Gaemi."
They called for better urban flood management and targeted warnings that offer more information on the likely impacts of a storm.
The study was released as Typhoon Shanshan made landfall in Japan, which issued its highest level warning for wind and storm surges.