The high temperature event in July 2018 caused record-breaking human damage throughout Japan. Large-ensemble historical simulations with a high-resolution atmospheric general circulation model showed that the occurrence rate of this event under the condition of external forcings in July 2018 was approximately 20%. This high probability was a result of the high-pressure systems both in the upper and lower troposphere in July 2018. The event attribution approach based on the large-ensemble simulations with and without human-induced climate change indicated the following: (1) The event would never have happened without anthropogenic global warming. (2) The strength of the two-tiered high-pressure systems was also at an extreme level and at least doubled the level of event probability, which was independent of global warming. Moreover, a set of the large-ensemble dynamically downscaled outputs revealed that the mean annual occurrence of extremely hot days in Japan will be expected to increase by 1.8 times under a global warming level of 2 degrees C above pre-industrial levels.
1.Japan Meteorol Agcy, Meteorol Res Inst, 1-1 Nagamine, Tsukuba, Ibaraki 3050052, Japan 2.Univ Tokyo, Atmosphere & Ocean Res Inst, Chiba, Japan 3.Natl Inst Environm Studies, Ibaraki, Japan
Recommended Citation:
Imada, Yukiko,Watanabe, Masahiro,Kawase, Hiroaki,et al. The July 2018 High Temperature Event in Japan Could Not Have Happened without Human-Induced Global Warming[J]. SOLA,2019-01-01,15A:8-12