We investigated the effect of artificial marine cloud brightening on extreme temperatures over East Asia. We used simulation data from five global climate models which have conducted the GeoMIP G4cdnc experiment. G4cdnc was designed to simulate an increase in the cloud droplet number concentration of the global marine lower clouds by 50% under the greenhouse gas forcing of the RCP4.5 scenario. G4cdnc decreased the net radiative forcing in the top of the atmosphere more over the ocean, alleviating the rise in mean temperature under RCP4.5 forcing. For extreme temperatures, G4cdnc reduced both the monthly minimum of daily minimum temperature (TNn) and monthly maximum of daily maximum temperature (TXx). The response of TNn was higher than that of TXx, especially in the winter, over the Sea of Okhotsk and the interior of the continent. This spatial heterogeneity and seasonality of the response were associated with sea ice–albedo and snow–albedo feedbacks. We also calculated the efficacy of warming mitigation as a measure of the relative effect of geoengineering. The efficacy for TXx was higher than that for TNn, opposite to the absolute effect. After the termination of geoengineering, both TNn and TXx tended to rapidly revert to their trend under the RCP4.5 forcing.

Recently, the CORDEX-East Asia team completed climate change simulations based on five regional climate models (RCM) under four Shared Socioeconomic Pathways (SSP) scenarios. In this study, the performance of five RCMs and their ensemble averages for present-day climate simulations are evaluated. All RCMs have relatively high performance for climatology patterns for Korea, East China and Japan, while relatively low performance is observed for the Tibetan plateau. Many RCMs share cold and wet biases. Future climate changes under four SSP scenarios are analyzed for the end of 21st century (2081 ~ 2100) compared to present day (1995 ~ 2014). East Asia is expected to experience temperature increases of 2.4℃ to 6.2℃ and precipitation increases of 6.7% to 12.6%, with stronger changes in higher-emission scenarios. Among the five RCMs, HadGEM3-RA projects the largest increase in temperature while GRIMs is characterized by the strongest increase in precipitation. In line with mean warming rates, warm extreme days (TX90p) are projected to increase by 35.7 ~ 93.3 days and cold extreme days (TN10p) are projected to decrease by 23.4 ~ 35.2 days. The results of this study can be used as a reference for future detailed analyses of East Asian climate change and its impacts as well as for emphasizing the importance of carbon neutrality.

This study presents a future projection of temperature over the Korean Peninsula (KP) under the global warming targets of 1.5℃ and 2.0℃ set in the 2015 Paris Agreement. For projection, simulation data from the multi-Regional Climate Model (RCM) ensemble in Coordinated Regional Climate Downscaling Experiment (CORDEX)-East Asia (EA) Phase 2 are used. Under the 2.0℃ (1.5℃) global warming condition, mean temperature over KP would increase 2.13℃ (1.51℃) compared to the present period (1985 ~ 2005 years). Extreme minimum and maximum temperature intensity indices (TNn and TXx) would also increase 2.61℃ (1.91℃) and 2.38℃ (1.58℃). In addition, changes in probabilities of extreme temperature events that occurs once in 20 years during the present period are investigated. Extreme cold events would occur once in 28.9 years (22.6 years) and warm events once in 5.9 years (7.2 years). Meanwhile, there are several noteworthy points about the future projection. The temperature over KP would increase more over the northern KP than the southern KP and this feature is more distinct in TNn. The uncertainties of the projection are higher for the 1.5℃ warming condition than the 2.0℃ warming condition and for extreme temperature versus mean temperature. The spatial pattern of change in extreme temperature frequency is different from that of intensity. In other words, a smaller increase in the frequency of extreme cold events is expected over the inland KP.

The study predicts the future photovoltaic power generation potential (PVpot) changes over South Korea based on high-resolution climate change scenarios. According to the four Shared Socioeconomic Pathways (SSP) scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5), at the late 21st century, surface down-welling shortwave radiation, which has a major impact on PVpot, is expected to increase (by about +0.7 ∼ +3.5 W/m²) compared to the present-day. However, the increase or decrease of PVpot depends on the level of emissions in the future. In the low-emissions scenario, PVpot is expected to increase (by about +1.3%), while that in the high-emissions scenarios, PVpot isare expected to decrease (by about -0.7 ∼ -2.0%). As the temperature increases significantly, the temperature of the solar cell panels increase, and the performance ratio of PVpot decreases. This means that, even though the surface down-welling shortwave radiation increases, the increase in temperature may offset the positive impact on PVpot. Seasonally, PVpot is expected to increase (by about +2.3 ∼ +4.0%) in summer and decrease (by about -3.6 ∼ -7.1%) in winter. Overall, this study highlights the importance of considering the impact of climate change on solar energy. It also emphasizes the need to adopt low-emissions policies to mitigate the negative effects of climate change on renewable energy generation potential.

In this study, we classified climate zones over South Korea using high-resolution (1 km × 1 km) observational grid data (2000 ~ 2019) and projected future regional climate changes based on high-resolution climate change scenarios (2081 ~ 2100). We applied the K-means clustering method to observational annual mean temperature and total precipitation data to classify South Korea into the following six regions: mountainous-central-high/low elevation (A1/A2), plain-central/southern (B1/B2), and mountainous-southern-high/low elevation (C1/C2). Currently, mean temperatures are highest/lowest at B2/A1 (12.4°C/8.0°C) and total precipitation is highest/lowest at C1/B1 (3312 mm/1182 mm). During the late 21st century, under a low-emission scenario (SSP1-2.6), annual mean temperatures are projected to increase by 2.3 ~ 2.4°C across the six climate zones; under a high-emission scenario (SSP5-8.5), temperature is expected to increase by 5.9°C (C1) to 6.5°C (A2). Total precipitation is projected to increase most in C1 (209 mm/456 mm) and least in B1 (21 mm/155 mm) under SSP1-2.6/SSP5-8.5. Extreme heat events (TXx) will increase across all regions, especially in central areas (A1, A2, B1) of South Korea. Heavy rainfall events (RX1D) will increase most in southern areas (B2, C1, C2), especially in C1, with increases exceeding 100 mm/day. Finally, extreme climate events are projected to occur more frequently across most regions. The intensities of future extreme climate events are expected to increase not only under high-carbon scenarios, but also under low-carbon scenarios. The results of this study are fundamental data for establishing region-specific climate change adaptation strategies.