Assessment of precipitation extremes in India during the 21st century under SSP1-1.9 mitigation scenarios of CMIP6 GCMs

This study used a 30-year observed (1985-2014) precipitation, and the latest Coupled Model Intercomparison Phase 6 (CMIP6) Shared Socioeconomic Pathways (SSPs) based precipitation scenarios to assess the impact of precipitation extremes in near future (2020-2049) and far future (2070-2099) periods over India. For the assessment of precipitation extremes, standard extreme precipitation indices (EPIs) such as mean precipitation, cumulative wet days (CWD), cumulative dry days (CDD), number of rainy days (NR), precipitation events between 10 and 20 mm (P1020), precipitation events between 20 and 40 mm (P2040), precipitation events > 40 mm (PG40), annual maximum 1-day precipitation (Rx1day), and annual maximum 5-day precipitation (Rx5day) have been utilized. The percentage of change (or magnitude of change) has been calculated between CMIP6 scenarios and observed precipitation for all EPIs in the near future (NF-2020-2049) and far future (FF-2070-2099) times. The CMIP6 global climate models (GCMs) contain a significant amount of uncertainty. Thus, the quantile mapping approach has been applied to correct the bias in CMIP6 scenarios with reference to observed precipitation. This study also compares the results of precipitation extremes obtained in this study with previously published CMIP5 GCMs based precipitation extreme scenarios. This study's observations clarified that a significant seasonal diversity and individuality existed among all the selected CMIP6 GCMs based precipitation scenarios (2020-2099) across India. As per EPIs, such as CDD based plots showed an increase (25-75%) in CDD over significant portions of India, while CWD plots showed an increase of CWD over a few areas of northwest, central, and northeastern India regions. In the case of event-based indices, all four CMIP6 GCMs showed some distinctive behavior, but the overall extremely high precipitation events such as PG40 showed a significant increase (25-80%) in both NF and FF times across India, except for a few grids.