The Impact of Climate Change on Precipitation Extremes Across East Asia and Japan

Abstract

We investigated the impact of climate change on precipitation extremes across East Asia, particularly Japan, by evaluating selected extreme precipitation indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDI) using historical simulations (1981-2010) of 22 Global Climate Models (GCMs) of the sixth Coupled Model Intercomparison Project (CMIP6), and reanalysis dataset of the Japanese 55-year (JRA-55), the National Centers for Environmental Prediction (NCEP) and National Center for Atmospheric Research (NCAR) NCEP-NCAR, and ERA5. The CMIP6 multi-model ensemble median (CMIP6-EnM) can generally capture the extreme precipitation patterns of East Asia and Japan, could reproduce historical spatial patterns of precipitation events, and it out-performs all 22 individual GCMs of CMIP6 with a smaller normalized 𝘙𝘔𝘚𝘌’ₓ[Y]. Over 1958-2014, East Asia has experienced significant warming especially in high latitude areas (over 3℃ in the Arctic), but drying trends limited only to some parts of Asia. Japan has experienced relatively modest warming trends by about 0.2-0.3℃ partly because it is surrounded by water. Over 1958-2014, East Asia and Japan had generally experienced drying trends between 1960s and 1990s, but from 1990s onwards, Japan has been experiencing wetting trends. In general, historical changes in extreme precipitation events based on the NCEP-NCAR reanalysis data are larger than JRA-55 reanalysis data, but changes based on both datasets are larger than that of CMIP6-EnMedian because of the averaging effect of using the median of simulations of GCMs of CMIP6. Under climate warming, Japan will likely become wetter, but changes will likely be less than the increase in atmospheric water vapor expected at about 7%/℃ (Clausius Clapeyron scaling).