[A-AS07] 大気化学

[AAS07-04] 2010年代の中国SLCFs排出量変動が東アジア・全球気候に与える影響

*須藤 健悟^1,2、王 靖凌¹ (1.名古屋大学大学院環境学研究科地球環境科学専攻、2.海洋研究開発機構)

キーワード：短寿命気候影響物質、二酸化硫黄、気候変動、化学気候モデル、中国排出量

This study investigates the temperature and precipitation changes (especially in East Asia) from 2012 to 2019 under the scenario of emission reduction due to China's emission reduction policies using the chemistry-climate model CHASER (MIROC) with the Chinese emission inventory MEIC. Our model simulation reveals that influences of the rapid SO₂ emission reduction and increases in well-mixed greenhouse gases (WMGHG) cause regionally different changes in temperature and precipitation in East Asia exhibiting almost opposite change patterns for SO₂ and WMGHG influences. The model calculates a significant increase in temperature in eastern China and its eastern seas, Japan, and other regions with also a large precipitation increase near Japan, but a decrease in precipitation in eastern China and adjacent seas. For both surface temperature and precipitation, the decrease in Chinese SO₂ emission has the same magnitude of impact as the increase in WMGHGs, suggesting the important role of Chinese SO₂ reduction in the decadal climate change in the 2010s. The simulation shows that the precipitation changes due to a decrease in SO₂ and an increase in WMGHG are both attributed to the induced large-scale changes in atmospheric circulation and cloud distribution in East Asia. Our additional simulation shows that the solo impact of SO₂ reduction on surface temperature may be confined within South Asia and China, but this may be largely amplified by the coinciding NOx reduction in China to give very significant warming in North China to Mongolia and Russia. Furthermore, we also found that the global pattern of surface temperature changes during the 2010s can be also well attributed to the reduction in SO2 emissions in China, indicating a potentially large contribution of regional SO₂ and aerosol emissions to global climate change. Interannual variation in biomass burning emissions and other anthropogenic emission changes (for BC/OC/NH3) which are not treated in this study should be examined as well as for SO2/NOx.
By investigating the impact of China's emission reduction policies like in this study, we can detect that while the policy has effectively curbed the deterioration of air quality, it has indeed brought about significant changes in precipitation in the surrounding region and contributed to climate change in East Asia and the globe, which may further lead to extreme weather events such as droughts and high temperatures. In addition, this modeling exercise can be good training for chemistry-climate models that target SLCFs impacts.