Abstract
High-resolution regional climate model (RCM) simulations are found to be very useful in deriving realistic climate change projection information. This study uses high-resolution dynamical downscaling framework (CCSM4-WRF) for India. To delineate the advantage of high resolution, we compared the results of 9-km resolution CCSM4-WRF simulations against the 50-km resolution RCM simulations under Coordinated Regional Climate Downscaling Experiment-South Asia (CORDEX-SA) program. Quantitative estimations show that majority of CORDEX-SA models exhibit large dry bias (< − 4 mm/day) and low pattern correlation coefficient (PCC) over the Western Ghats (WG). Mean climatology of Indian summer monsoon (ISM) rainfall simulated by high-resolution CCSM4-WRF outperforms the CORDEX-SA RCMs with low negative biases (~ 1 mm/day) and high PCC (≥ 0.755). This skill of CCSM4-WRF provides better confidence in its future projection at local scale. CCSM4-WRF projects future intensification of monsoon rainfall over most parts of India and reduction over southern WG, which is consistent with recent observed trends, but none of the CORDEX-SA RCMs could simulate this rainfall reduction. For all-India rainfall, ensemble mean of CORDEX-SA models projects an increase by 1.3 ± 0.9 mm/day and CCSM4-WRF projects 0.67 mm/day. Projected changes in socioeconomic variables such as population and gross domestic product (GDP) exhibit future enhancement over most parts of India but with spatial heterogeneity. Shared socioeconomic pathways scenarios show pronounced future population growth over Indian coastal areas and large enhancement in productivity over urban areas. Therefore, climate change projection information of ISM rainfall, together with enhanced future population and GDP, is useful for taking necessary steps for adaptation and mitigation in a sustainable manner.
Highlights
India is among the monsoon-dominant tropical countries, with majority of the rural population still dependent on agriculture
From the spatial distribution of mean bias of 14 CORDEX regional climate model (RCM), we found that only a few models simulate the spatial heterogeneity of the summer monsoon rainfall over India, with the least bias of 1–2 mm/day
This study evaluates the high-resolution climate change projection of Indian summer monsoon (ISM) rainfall under the RCP8.5 scenario derived from dynamically downscaled CCSM4-Weather Research and Forecasting (WRF) projections
Summary
India is among the monsoon-dominant tropical countries, with majority of the rural population still dependent on agriculture. Rainfall received over the country has greater socioeconomic importance than other meteorological variables. Orographic influence is prominent in the distribution of rainfall over India, especially the west coast and northeast India. This is because the prevailing moisture-laden south-west monsoon winds blow almost at right angle to the Western Ghats (WG) and the Khasi-Jaintia hills (Rao 1976). Global warming plays a decisive role in the strength and variability of the future Indian summer monsoon (ISM) rainfall. Even minor changes in the country’s rainfall variability (in spatial or temporal scale) due to global warming can have an immense impact on water resources and agricultural production (Gadgil 1995; Webster et al 1998). This, in turn, affects food security, livelihood of farmers, and economy of the country
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