Future Projection of Precipitation Bioclimatic Indicators over Southeast Asia Using CMIP6

Precipitation is a key meteorological component that is directly related to climate change. Quantifying the changes in the precipitation bioclimate is crucial in planning climate-change adaptation and mitigation measures. Southeast Asia (SEA), home to the world's greatest concentration of ecological variety, needs reliable monitoring of such changes. This study utilized the global-climate models from phase 6 of coupled model intercomparison project (CMIP6) to examine the variations in eight precipitation bioclimatic variables over SEA for two shared socioeconomic pathways (SSPs). All indicators were studied for the near (2020-2059) and far (2060-2099) futures to provide a better understanding of the temporal changes and their related uncertainty compared to a historical period (1975-2014). The results showed a high geographical variability of the changes in precipitation-bioclimatic indicators in SEA. The mainland of SEA would experience more changes in the bioclimate than the maritime region. The multimodel ensemble (MME) showed an increase in mean annual rainfall of 6.0-12.4% in most of SEA except the Philippines and southern SEA. The increase will be relatively less in the wettest month (15%) and more in the driest month (20.7%) in most of SEA; however, the precipitation in the wettest quarter would increase by 2.85%, while the driest quarter would decrease by 1.0%. The precipitation would be more seasonal. In addition, the precipitation would increase over a larger area in the wettest month than in the driest month, making precipitation vary more geographically.