Why are typhoons occurring frequently in Southeast Asia?
Typhoon Yagi, the most powerful tropical cyclone to strike Asia this year following Hurricane Beryl, has caused widespread devastation across Myanmar, Vietnam, Laos, and Thailand. The typhoon has displaced around 631,000 people and has claimed over 500 lives.
In another incident, two people died in China’s eastern Jiangsu province as Typhoon Bebinca brought torrential rains and powerful winds before easing into a tropical storm. More than 414,000 people were evacuated ahead of the powerful winds and torrential rain.
Why are these storms occurring more frequently and why are they so intense?
What is a typhoon?
A typhoon is a form of cyclone that has wind speeds of 119 kmph and above. It develops over warm ocean waters near the equator. When warm, moist air rises from the ocean surface, it creates a low-pressure area. Over the Atlantic and East Pacific, typhoons are commonly called "hurricanes."
Typhoon Yagi, with peak winds of 260 kmph, reached Category 5 on the Saffir-Simpson Hurricane Wind Scale, signifying its extreme strength. Category 5 storms are among the most destructive, with winds exceeding 252 kmph.
Typhoon Bebinca with top wind speeds of 151 kph (94 mph) near its eye reached category 1 storm on the Saffir-Simpson Hurricane Wind Scale.
There is a consensus among experts that with rising global temperatures, tropical cyclones are becoming more intense. For instance, a study published in the journal Climate and Atmospheric Science in July this year showed that tropical cyclones in Southeast Asia are now forming closer to coastlines, intensifying more rapidly, and lingering longer over land.
This could be happening primarily because of the warmer surface temperatures of the ocean. Global mean sea surface temperature has gone up by close to 0.9 degrees Celsius since 1850 and around 0.6 degrees Celsius over the last four decades.
Higher sea surface temperatures cause marine heat waves, an extreme weather event, which can also make storms like hurricanes and tropical cyclones more intense. Warmer temperatures escalate the rate of evaporation along with the transfer of heat from the oceans to the air. When storms travel across hot oceans, they gather more water vapour and heat. This results in stronger winds, heavier rainfall, and more flooding when storms reach the land.
The increasing unprecedented strengths and impact of these storms have resulted in severe humanitarian crises across several countries in South & Southeast Asia. The response to this disaster highlights the need for international collaboration, particularly in engaging with responsible authorities and civil society to provide aid and support to those most affected.