Uncertainties in future climate projections and consequential impact on maize productivity

Abstract

There exist a huge uncertainty cascade in projecting the future climate and in-turn using the same in assessing the impact on crop yields. To address the problem of projecting the future climate over Tamil Nadu in Southern India, 29 Global Circulation Models defined under coupled model inter comparison project (CMIP5) of IPCC were employed for understanding the range of deviations in future climate from current condition. Outputs of representative concentration pathway (RCP) 4.5 and 8.5 scenarios for mid-century were processed for impact assessment. Selected models output was forced in dynamic crop simulation model DSSAT for assessing the impact on spatial variability in maize productivity over Tamil Nadu and possible adaptation options were tailored forreducing impacts. During the Northeast Monsoon (NEM), the maximum temperature is expected to rise by 2.0 °C for RCP 4.5 and 3.0 °C for RCP 8.5, while the minimum temperature is expected to rise by 1.8 °C for RCP 4.5 and 2.4 °C for RCP 8.5 in the mid-century. Rainfall is anticipated to vary from -22.8 to 21.1% for RCP 4.5 and -31.3 to 32.6% for RCP 8.5. The magnitude of decline in yield would be more in RCP 8.5 (30.7%) over RCP 4.5 (10.6%) scenario. Impacts of future climate change could be reduced by altering the date of sowing (early sowing) to September 1st against September 15th (normal sowing) under RCP 4.5 and RCP 8.5 scenarios. Additional dose of (25%) fertilizer had positive response with yield increase up to 15% under future climatic conditions.