Integrated Assessment of Climate Change and Adaptations Impacts on Yields and Incomes of Irrigated Maize Farm Systems in Tamil Nadu, India.

Irrigated maize production system in the Coimbatore District, Tamil Nadu was considered for integrated analysis of climate change impacts on farm household income and poverty through maize yields. Calibrated APSIM and DSSAT crop models were used to simulate maize yields combining future climate parameters derived from RCP 8.5 for Mid-century time frame under the CCSM4, GFDL-ESM2M, HadGEM2-ES, MIROC5 and MPI-ESM-MR GCMs, and management inputs were derived from economic farm survey for the period 2008. These yields were converted to projected future farm yields corresponding to the simulations using the random yield effect model. Global IMPACT economic model projections were used to adjust simulated future maize yields and prices for answering the key questions sought to be addressed through this research. Changes to the future system were projected based on variable values derived from the developed RAPs.

Three questions, viz. sensitivity of the maize production system to climate change (Q1), impact of climate change on future agricultural production systems (Q2) and impacts of potential adaptation packages on the climate impacted future production system are addressed in the study.

Relating to Q1, APSIM indicated lower yields under climate change, lower mean net returns, lower per capita income and higher poverty levels for System 2, and DSSAT results projected mixed impacts. Maize crop yield is sensitive to the crop model used, followed by climate projections represented by GCMs. At farm level, other system activities influence the sensitivity of the whole system to climate change.

Results of the analysis for Q2 were similar to those from the earlier question in terms of trends. APSIM results in general predicted negative trends and DSSAT mixed trends.  Future systems in general have higher net farm incomes, higher per capita income and reduced poverty levels due to autonomous technological improvements as predicted by global models and RAPs. Climate change however impacts the future system. All GCMs and crop models poverty increased, though marginally, in the range of 0.37% to 1.84% due to climate change.

Considering potential adaptation options in Q3, an adaptation package with date of sowing, water saving and livestock improving components was considered for irrigated maize production system of Tamil Nadu.   Between APSIM and DSSAT results, there were consistent increases in net returns and per capita income and reductions in poverty rates across all GCMs. Thus, while irrigated maize production system is both sensitive and susceptible to climate change impacts, both natural trends in productivity improvements and adaptations offer scope to reduce climate change impacts on the system. There is thus scope for a vast majority of the farms (upwards of 90%) to adopt this adaptation package to partially mitigate the negative effects of climate change. Farms are likely to suffer due to climate change with the current or future production systems at least marginally in spite of future yield trends. With adaptation there are increased net farm incomes, per capita incomes and reduced poverty levels indicating scope for households being better off.