Impact of regional climate model projected changes on rice yield over southern India

This study addresses the impact of projected changes to northeast monsoon on rice yield during rabi season (September-December) in Tamil Nadu by using a three-step approach. First, coarse-resolution global climate models that realistically capture the mean monsoon characteristics were selected. Second, lateral and boundary conditions taken from selected global models' projections are employed to run a high-resolution regional climate model. Third, climate variables from regional model being fed into panel data regression model. For different scenarios and for mid and end of century projections, in conjunction with projected rainfall, a comprehensive assessment is carried out to underscore the sensitivities of maximum and minimum temperatures under different stages of rice production, viz. vegetative, reproductive and maturity phases, and to the concept of growing degree days (GDD, cumulative heat effect). Irrespective of scenarios, in response to an increase in projected monsoon rainfall and surface temperature conditions, the regression model estimates an increase of rice yield of about 10-12% by mid-century and 5-33% by the end of the century. In the regression model, the baseline coefficients were estimated from observed rainfall and temperature available from India Meteorological Department (IMD). The projected changes in rice yield, however, remain unchanged for baseline coefficients estimated from regional climate model outputs (forced by reanalysis products) rainfall and temperature. The robust results obtained here provide confidence to the findings.