Domestic researchers announced a projection that extreme heavy rainfall during the summer in Korea will move up from August to July due to climate change. In particular, the frequency of extreme heavy rainfall exceeding 30 mm per hour is expected to increase by up to 3.7 times compared to the present, indicating that a comprehensive review of summer disaster response plans may be necessary.
Pohang University of Science and Technology POSTECH announced on the 22nd that Professor Min Seung-ki and Dr. Seo Ga-young's research team discovered this fact by analyzing ultra-high-resolution climate models.
Cases of sudden heavy rain that flooded areas around Gangnam Station in Seoul in August 2022, and last week's concentrated downpours across the nation, show that unpredictable extreme rainfall is occurring more frequently. Climatologists report that as climate change accelerates, both the frequency and intensity of short-term extreme rainfall are expected to increase. Accurately predicting when and how often such extreme heavy rainfall will occur is crucial for disaster response and minimizing damage.
The research team used a much denser ultra-high-resolution model (2.5 km resolution) to analyze the monthly changes in the frequency of extreme rainfall exceeding 30 mm per hour under two greenhouse gas emission scenarios. One scenario is the 'low-emission scenario (SSP1-2.6),' in which the world actively reduces carbon emissions, and the other is the 'high-emission scenario (SSP5-8.5),' in which carbon emissions increase at current levels.
The analysis comparing the current climate (2001-2005) with the future climate (2091-2095) showed that under both scenarios, the occurrence timing of extreme heavy rainfall exceeding 30 mm per hour is expected to move up by one month. Currently, most of these heavy rainfalls occur in August, but in the future, the 'maximum peak' of this heavy rainfall will be advanced by one month. In particular, the frequency of extreme heavy rainfall in July is expected to increase by about 2 times under the low-emission scenario and about 3.7 times under the high-emission scenario.
In the high-emission scenario, a nearly stationary front is expected to form between the northbound low pressure and southbound high pressure in the Korean Peninsula, leading to a significant increase in weather patterns where heavy rainfall lingers in this boundary area for extended periods. The research team explained that this change is a phenomenon that occurs as the North Pacific high pressure and mid-latitude pressure trough develop more strongly due to warming. In other words, the characteristics of the pressure systems supplying moisture to Korea in the summer are changing due to global warming.
Professor Min Seung-ki noted, "This study is significant in that it analyzed the month in which extreme heavy rainfall will concentrate during summer using high resolution," and emphasized the need to refine disaster response plans on a monthly basis in preparation for the possibility of rainfalls being advanced.
The results of this research were published in the international journal npj Climate and Atmospheric Science on June 5.
References
npj Climate and Atmospheric Science (2025), DOI: https://doi.org/10.1038/s41612-025-01067-z