Shifting Velocity of Precipitation Extremes over India under Climate Change

Abstract

Climate change is leading to alterations in the dynamic climate systems worldwide. The Indian Summer Monsoon (ISM) is one such climate system that supports more than a billion population and drives the Indian economy. The ISM is governed by intra-annual to inter-decadal variabilities. However, anthropogenic climate change is inducing unprecedented transformations in this natural system, such as the increased probability of precipitation extremes (dry and wet), changes in their frequency and duration, spatial variabilities, etc. These changes, in turn, impact the human and ecological systems due to droughts, floods, and prolonged dry spells. In such scenarios, it is essential to gain insights into the projected precipitation extremes (PEs) changes. The velocity of climate change (VoCC) or climate velocity can help us project the temporal and spatial shift of PEs especially in terms of their intensities. VoCC is a regional metric of climate change, defined as the ratio of the temporal gradient of a particular climate variable (temperature, precipitation, humidity, etc.) with its spatial gradient, and the resultant units are in km/year. In the current study, the climate velocities of 50th, 75th, 95th, 99.5th, and 99.9th percentiles of precipitation for the JJAS season are projected over India and its different biogeographic zones for the four time periods: historical (1976-2000), near-future (2025-2049), mid-future (2050-2074) and far-future (2075-2099). ROM, a regional earth system model over the CORDEX-South Asia domain was used in the study. It was found that ROM showed a better resemblance with observation in simulating the PEs over other regional climate models (RCMs). The intense rainfall (95th percentile: R95) is expected to be enhanced over most of the study region in mid future and far future. Interestingly, very intense rainfall (99.9th percentile: R99) showed robust increases in the near and mid-future as compared to the far future. The PEs also exhibited higher velocities as compared to the median values. The detailed results will be discussed further in the presentation.