Predicting Irrigated and Rainfed Rice Yield Under Projected Climate Change Scenarios in the Eastern Region of India A. V. M. Subba Rao 2 & Arun K. Shanker 1 & V. U. M. Rao 2 & V. Narsimha Rao 2 & A. K. Singh 3 & Pragyan Kumari 4 & C. B. Singh 5 & Praveen Kumar Verma 6 & P. Vijaya Kumar 2 & B. Bapuji Rao 2 & Rajkumar Dhakar 2 & M. A. Sarath Chandran 7 & C. V. Naidu 8 & J. L. Chaudhary 6 & Ch. Srinivasa Rao 7 & B. Venkateshwarlu 9 Received: 7 February 2014 /Accepted: 6 April 2015 # Springer International Publishing Switzerland 2015 Abstract Numerous estimates for the coming decades project changes in precipitation resulting in more frequent droughts and floods, rise in atmospheric CO 2 and temperature, exten- sive runoff leading to leaching of soil nutrients, and decrease in freshwater availability. Among these changes, elevated CO 2 can affect crop yields in many ways. It is imperative to understand the consequences of elevated CO 2 on the produc- tivity of important agricultural crop species in order to devise adaptation and mitigation strategies to combat impending cli- mate change. In this study, we have modeled rice phenology, growth phase, and yield with the BDecision Support System for Agrotechnology Transfer (DSSAT) CERES rice model^ and arrived at predicted values of yield under different CO 2 concentrations at four different locations in Eastern India out of which three locations were irrigated and one location was rainfed. The ECHAM climate scenario, Model for Interdisci- plinary Research on Climate (MIROC)3.0 climate scenario, and ensemble models showed different levels of yield increase with a clear reduction in yield under rainfed rice as compared to irrigated rice. A distinct regional and cultivar difference in response of rice yield to elevated CO 2 was seen in this study. Results obtained by simulation modeling at different climate change scenarios support the hypothesis that rice plant re- sponses to elevated CO 2 are through stimulation of photosyn- thesis. Realization of higher yields is linked with source sink dynamics and partitioning of assimilates wherein sink capac- ity plays an important role under elevated CO 2 conditions. Keywords Climate change . Simulation modeling . Elevated CO 2 . Sink capacity . Photosynthesis 1 Introduction Global climate change will have a decisive impact on crop production, and the prediction of the extent of this has emerged as a major research priority during the past decade. Numerous estimates for the coming decades project changes in precipitation resulting in more frequent droughts and floods, rise in atmospheric CO 2 and temperature, extensive runoff leading to leaching of soil nutrients, and decrease in freshwater availability. World agriculture faces overwhelming * Arun K. Shanker arunshank@gmail.com 1 Division of Crop Sciences, Central Research Institute for Dryland Agriculture (CRIDA), Santoshnagar, Saidabad PO, Hyderabad 500 059, India 2 All India Coordinated Research Project on Agrometeorology, Central Research Institute for Dryland Agriculture (CRIDA), Santoshnagar, Saidabad PO, Hyderabad 500 059, India 3 Department of Agrometeorology, N.D. University of Agriculture and Technology, Kumarganj, Faizabad 224 229, Uttar Pradesh, India 4 Department of Agricultural Physics, Birsa Agricultural University, Kanke, Ranchi 834 006, Jharkhand, India 5 Department of Agronomy, C.S. Azad University of Agriculture and Technology, Nawabganj, Kanpur 208 002, Uttar Pradesh, India 6 Department of Agro Meteorology, College of Agriculture, Indira Gandhi Krishi Vishwavidyalaya (IGKV), Krishak Nagar, Raipur 492004, Chhattisgarh, India 7 Central Research Institute for Dryland Agriculture (CRIDA), Santoshnagar, Saidabad PO, Hyderabad 500 059, India 8 Andhra University, Vishakapatnam, Andhra Pradesh, India 9 Vasantrao Naik Marathwada Krishi Vidyapeeth Parbhani (VNMKV), Parbhani 431402, Maharashtra, India Environ Model Assess DOI 10.1007/s10666-015-9462-6