Future Characteristics of Extreme Precipitation Indicate the Dominance of Frequency Over Intensity: A Multi-Model Assessment From CMIP6 Across India

This study presents a comprehensive analysis on the past and future changes in precipitation extremes and quantifies the relative contributions from its frequency and intensity across India, considering five extremeness levels, denoted by 95th, 99th, 99.9th, 99.95th, and 99.97th percentile. Gridded station-based observations from the historical period (1951-2020) and simulations from 14 General Circulation Models for the future (2021-2100), participating in the Coupled Model Intercomparison Project phase 6 (CMIP6) are considered. Apart from an overall increasing pattern of precipitation extremes, it is noticed that the contribution of frequency dominates over intensity. Specifically, the frequency of 99th percentile daily rainfall is projected to increase approximately by two- (SSP245) to three- (SSP585) times in future. We also proposed a new zoning of entire Indian mainland, identified as six Homogeneous Precipitation Zones (HPZs). HPZ-wise analysis reveals that the increase in frequency dominates over intensity for all the HPZs with a varying extent. For instance, increase in frequency is more for the climatologically high-precipitation zones (HPZ-3: Western Ghats, and HPZ-6: North-east India), whereas increase in intensity is more for the low-precipitation zones (HPZ-1: North-west India, and HPZ-4: Peninsular India). The degree of increase gets even more pronounced under the worst scenario SSP585, indicating a potential impact of anthropogenic activities on changing precipitation extremes. Findings of this study should be accounted in the climate change adaptation and mitigation strategies for future.

Automated summary

This study presents a comprehensive analysis of past and future changes in precipitation extremes in India, revealing that the contribution of frequency dominates over intensity. The study also proposes a new zoning of the Indian mainland, showing varying responses to precipitation extremes in different regions.