A. The 9th typhoon ‘Jongdari’, which first affected the Korean Peninsula this year, fortunately weakened early. Although it brought a lot of rain nationwide, the damage was not significant. However, the problem lies ahead. Due to climate change, typhoons are becoming stronger, and since last year, the accumulated heat energy in the entire earth due to El Niño is causing typhoons to be more powerful. This year, the sea surface temperatures worldwide are reaching record highs. Typhoons that occur during this time are even more powerful. Furthermore, with the recent transition from El Niño to La Niña, there is a higher possibility of typhoons heading towards the Korean Peninsula. Therefore, this autumn, there is a high possibility of powerful typhoons or even if typhoons are avoided, there is a high chance of a record-breaking autumn rainy season.
Typhoons occur in the North Pacific Ocean between 5 and 20 degrees north latitude. They form a giant tropical low-pressure system with a radius exceeding the east-west width of the Korean Peninsula by up to 500 km, accompanied by strong winds exceeding 17 m/s and heavy rain. According to the Meteorological Administration’s ‘2023 Typhoon Analysis Report’, an average of 3.1 typhoons affect the Korean Peninsula each year, and in some years, such as 2019, the number can increase to 7. Typhoons on the Korean Peninsula are concentrated in August and September-October.
The reason why September typhoons are feared is that the sea temperature changes more slowly than the air temperature. The sea temperature, which starts to rise in summer, peaks in late September. Typhoons gain momentum from the heat energy of the sea surface, making them more powerful and bringing more precipitation. When the typhoon, filled with warm water vapor, encounters cold air as it descends in autumn, it brings even more rain. In addition, in autumn, the North Pacific High that covered the Korean Peninsula contracts. The path of the typhoon moving along the outskirts of the high-pressure system heads towards the inland of the Korean Peninsula, resulting in greater damage.
The worst-known typhoons, Sara (1959) and Maemi (2003), were both September typhoons. Typhoon Hinnumdo in 2022 affected the southern part of the Korean Peninsula, causing 12 deaths and missing persons.
The concern for typhoons this year is heightened due to the deepening climate crisis and the overlapping El Niño and La Niña conditions. El Niño and La Niña, irregular phenomena of sea temperature changes occurring every 2 to 7 years in the Pacific Ocean, affect weather patterns worldwide. Since May last year, the Earth’s temperature has been breaking records for the 15th consecutive month until July. The sea surface temperature has also set new records. The world’s sea surface temperature, which first exceeded 21 degrees last year, rose to 21.2 degrees in the first half of this year. Typhoons formed in such accumulated heat conditions become even more powerful.
Last autumn (September to November), which was in the La Niña conditions, saw the occurrence of four typhoons, which is fewer than the average of 10.7 typhoons, but the cumulative energy of the storms was similar to the average. As a result, strong typhoons occurred with less frequency, and the survival time of the typhoons was longer. Although not in autumn, Typhoon Khanun, which passed through the Korean Peninsula on July 28th last year, weakened on August 11th after a long 14-day activity.
Experts have expressed concerns about strong typhoons and autumn monsoons. Professor Kim Haedong of Keimyung University’s Department of Earth and Environmental Sciences said, “As La Niña settles in and the sea temperatures off the west coast of the Pacific rise significantly, the sea temperatures in Korea’s coastal waters are even higher than in equatorial regions.” Professor Gang Namyoung of Kyungpook National University’s Department of Geography explained, “With the operation of global warming and the overlap of La Niña, the western Pacific becomes warmer, which can lead to typhoons forming in the Taiwan and South China Sea areas. Even if these typhoons do not reach the Korean Peninsula, they play a role in transporting a lot of water vapor towards the Korean Peninsula.” Ultimately, it is predicted that in September, strong typhoons will come or, even if not typhoons, an unusual autumn rainy season is expected.
The key point is the North Pacific High. The western boundary of the North Pacific High becomes a passage for typhoons and rain, so it is important to watch where this boundary will be positioned in the future. Let’s hope that there will be no more weather disasters like in previous years.
Climate change – A journalist who knows a little, Park Gi-yong [email protected]