Warmer Climate Made Super Typhoon Ragasa 36% More Destructive in Southern China, Study Finds

As climate change intensifies, southern China can expect stronger and wetter typhoons in the future, researchers at Imperial College London said.

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Even small shifts in the intensity of a weather event can lead to massive increases in economic losses, a new study has warned after finding that climate change caused about 36% of Super Typhoon Ragasa’s direct damage to homes and properties in southern China.

Super Typhoon Ragasa, which at its peak was comparable to a Category 5 hurricane, battered the northern Philippines and Taiwan on September 22, claiming at least 25 lives. It then moved towards Hong Kong and southern China, bringing torrential rains, destructive winds and widespread flooding.

The rapid impact attribution study by Imperial College London showed that climate change, which is primarily the result of fossil fuel burning, boosted Ragasa’s peak wind speeds at landfall in southern China by 7% (approximately 13 km/h or 8 mph). Similar wind speeds would occur about once every 13 years without climate change. But in the current climate, which is 1.3C warmer than pre-industrial times, they are expected once every eight years.

Similarly, climate change made the rainfall from the typhoon’s eyewall 13% heavier. This increase in rainfall means that extreme events, which historically occurred about once every seven years in the region, are now expected every five years.

“In a world without climate change, a weaker typhoon would have been about 36% less damaging. This means climate change was behind more than a third of the economic damages from Typhoon Ragasa in China,” according to the study.

Total economic losses across Southeast Asia and China are not yet known, but estimates put them in the hundreds of millions of USD. Insured losses could potentially exceed tens of millions.

To study Ragasa, the research team used the Imperial College Storm Model (IRIS), a climate model used to determine how much human-caused climate change has intensified specific extreme weather events, such as a typhoon’s rainfall. It does so by comparing current atmospheric conditions to a simulated pre-industrial scenario.

“This study highlights the simple cost benefit of reducing emissions now, not sometime in the future as governments are having to reach deeper into their pockets to respond to extreme weather intensified by climate change,” said Emily Theokritoff of the Grantham Institute – Climate Change and the Environment at Imperial College London.

“The longer it takes to shift away from fossil fuels, the more intense and costly extreme weather events will become.”

Wetter and More Intense Storms

Tropical cyclones – commonly known as typhoons in the northwestern Pacific and hurricanes if they originate in the Atlantic or northeastern Pacific Ocean – are a rather common weather phenomenon. However, there has been a significant increase in their intensity in recent decades. Scientific observations link this to rising ocean temperatures.

“China appears to have prepared well for Ragasa,” said Ralf Toumi, Director of the Grantham Institute. But, he added, “as the climate warms, we can expect more typhoons to reach Categories 4 and 5. Storms of this strength risk massive damage, even with major preparations.”

In particular, the study warned that in a 2C warmer world, a Ragasa-like typhoon would cause 24% more damage. This is because once the storm reaches a certain threshold, structures and trees fail, creating a domino effect of destruction from flying debris. This causes costs to escalate rapidly, Toumi explained.

According to the UN, the world is headed for 2.6-3.1C of warming over the course of this century.

The study reinforces findings from research published last week. It concluded that tropical cyclones similar to Super Typhoon Ragasa are locally up to 10 mm/day – about 10% – wetter, around 1C warmer, and roughly 4% windier in today’s climate compared to the past. The same study also found that the heavy rains, storm surges, and widespread floods associated with Ragasa were intensified by climate change.

Featured image: NASA Johnson/Flickr.