Abstract
Abstract. The possibility of an impact of global warming on the Indian monsoon is of critical importance for the large population of this region. Future projections within the Coupled Model Intercomparison Project Phase 3 (CMIP-3) showed a wide range of trends with varying magnitude and sign across models. Here the Indian summer monsoon rainfall is evaluated in 20 CMIP-5 models for the period 1850 to 2100. In the new generation of climate models, a consistent increase in seasonal mean rainfall during the summer monsoon periods arises. All models simulate stronger seasonal mean rainfall in the future compared to the historic period under the strongest warming scenario RCP-8.5. Increase in seasonal mean rainfall is the largest for the RCP-8.5 scenario compared to other RCPs. Most of the models show a northward shift in monsoon circulation by the end of the 21st century compared to the historic period under the RCP-8.5 scenario. The interannual variability of the Indian monsoon rainfall also shows a consistent positive trend under unabated global warming. Since both the long-term increase in monsoon rainfall as well as the increase in interannual variability in the future is robust across a wide range of models, some confidence can be attributed to these projected trends.
Highlights
Indian summer monsoon rainfall affects the lives of the large population of India by determining its water availability as well as food security (Parthasarathy et al, 1988; Auffhammer et al, 2006)
We examine the mid-19th century to the end of the 21st century variability of Indian summer monsoon (ISM) rainfall simulated by 20 of the models that participated in the CMIP-5
Models are chosen according to the availability of the data: only those models are analyzed for which data for historic period (1850– 2005), Representative Concentration Pathways (RCPs)-8.5 and at least one more scenario were available at the time of the study
Summary
Indian summer monsoon rainfall affects the lives of the large population of India by determining its water availability as well as food security (Parthasarathy et al, 1988; Auffhammer et al, 2006). ISM intensity from speleothem record over southern Arabia shows a decreasing trend over the past century, which is attributed to the increase in sea surface temperature over the Indian Ocean (Burns et al, 2002). CMIP-5 models consistently project a significant increase in Indian summer monsoon rainfall sub-seasonal variability under unmitigated climate change (Menon et al, 2013). We use data from RCP model simulations in order to study the projected changes in the mean and variability of ISM rainfall in the future.
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