지구온난화에 따른 지역규모 대기질 영향평가 II

Abstract

Accumulated data obtained from satellite, surface, and upper air observations have shown that atmospheric concentrations of greenhouse gases affecting the earth's climate system have increased significantly since the Industrial Revolution. Over the last 250 years, concentrations of long-lived greenhouse gases such as carbon dioxide, methane, and nitrous oxide have increased 35%, 143%, and 18%, respectively, propelling global warming more aggressively than ever before. For example, the radiative forcing due to increased carbon dioxide emissions from fossil fuel consumption and cement manufacture have risen nearly 20% in the last 30 years. As is well known, the ongoing climate change(global warming) has been causing natural disasters such as floods, landslides, heat waves and wildfires while the earth's mean surface temperature has reached the highest level in the first half of 2010. Although research into climate change and its relationship to air quality has been vigorously pursued in some countries, few such studies have been undertaken in South Korea. Accordingly, the first year of study in 2009 was focused on building a down-scaling modeling system used to predict a three-dimensional meteorological field and its influences on regional scale air quality caused by climate changes. Subsequently, the impact of climate change on regional scale air quality was evaluated under the SRES A1B climate change scenario. Anthropogenic and natural emissions were fixed at the current value in forecasting current and future air qualities in order to closely investigate climate change effects alone. The results showed that the number of days exceeding national standard for 8-hour ozone concentration would increase by about 9 days in South Korea in 2055 as compared to 1995. In other words, the deterioration of air quality due to global warming would be certain even in the unlikely scenario that emissions remain at the current levels. Based on the results of the first year of the study, the current study, the second year, estimated changes in future air quality considering changes in both climate and emissions. Emissions of the projection year are based on 1) SRES A1B, 2) the maximum and 3) the minimum level of China's emissions. Moreover, the effects of climate change alone was measured with emission rate calculated at the present level. Simulation results for three summers current (from 1994-1996) and future (2054-2056) each in East Asia using the down-scaling meteorological modeling system indicated that the north pacific anticyclonic will strengthen and the seasonal rain front will move to the north in the future. The mean temperature in South Korea, Japan, and the north pacific area will increase by approximately 2℃, while precipitation will increase except for the eastern part of Tibetan Plateau and the north pacific area. In South Korea, the mean temperature will rise by 1.51℃, with the Youngnam area experiencing the largest increase of 1.75℃. In addition, the mean accumulated precipitation is expected to increase, with the Kangwon area experiencing the largest increase of 140mm. The mean PBL height decline of 24m on average is predicted overall in South Korea; however, the daily maximum mean PBL height increase of 18m and 8m in Youngnam and Honam areas respectively is expected, areas where a relatively dramatic increase of the mean temperature will likely materialize. The current study also examined the fluctuations in ozone concentration on the Korean peninsula, calculated using the regional air quality model (CMAQ). Results showed that even if emissions are maintained at the current levels, ozone concentration will certainly increase due to global warming. The effects of climate change alone in South Korea account for an increase of 7ppb in summertime daily average of maximum 8-hour ozone concentration. In particular, Youngnam and Honam areas, with predicted dramatic increases in average temperatures, will experience significant increases of approximately 8ppb. Taking China's emissions into consideration, the combined effect on air quality due to changes in both climate and emissions was investigated. The results showed that the daily average of maximum 8-hour ozone concentrations increase of around 16ppb under the SRES A1B, about 19ppb in the scenario of maximum future Chinese emissions, and about 5ppb with minimum Chinese emissions. Based on the results above, the study predicted that up to 22 additional days each year will exceed the 8-hour ozone concentration limit of 60ppb in the future in South Korea under the future climate and SRES A1B emission scenario. The contributions of different processes were assessed by means of the Process Analysis(PA) available within the CMAQ model. Providing the effects of all the physical processes and net effect of chemistry on model predictions, the process analysis indicated that the increased ozone concentration for the future in South Korea is mainly due to horizontal and vertical transport phenomena originating from China's wind flow. Following, the mortality effect of increased ozone concentration on the population of South Korea was calculated using the Concentration-Response function. It was estimated that the total number of premature deaths due to increased ozone concentrations in 2055 compared with 1995 is 4,160 under climate change and SRES A1B emission scenario, and 2,294 under climate change alone. Nor surprisingly, it is also expected that the number of premature deaths for the year 2055 might increase more significantly if future population and age distribution caused by extension of the average life expectancy is taken into consideration in this study. In conclusion, air quality will indubitably deteriorate if human activities continue as they are, not to mention under the SRES A1B emission scenario. Worse yet, the results presented here imply that the impacts of climate change on air quality in East Asia are more serious than any other region in the world. Accordingly, the policies related to emission reduction and strengthening of environmental standards enabling sustainable management of future air quality should be thoroughly prepared . Last but not least, adaptation strategies for public health also need to be considered carefully.