Bioclimatic modeling and FACE study forecast a bleak future for wheat production in India

Since the impact of future climate change on wheat productivity is inconsistent, we studied geographic distribution and yield of wheat using two global General Circulation Models (GCMs) and Free Air CO_2/O₃ Enrichment (FACE) experiments. The GCMs (IPSL-CM5A-LR and NIMR-HADGEM2-AO) with four Representative Concentration Pathways (RCPs) and 19 bioclimatic variables were used for distribution/ecological niche modeling (ENM). Currently cultivated eight wheat cultivars were exposed to individual treatment of (i) ambient CO₂, temperature, and ozone (ACO + AO + AT) representing the present climate scenario, and (ii) elevated CO₂ (550 ppm) (ECO), (iii) elevated temperature (+ 2 °C) (ET), (iv) elevated O₃ (ambient + 20 ppb) (EO), (v) elevated CO₂ + elevated O₃ (ECO + EO), and (vi) elevated CO₂ + elevated temperature + elevated O₃ (ECO + EO + ET) under FACE facility simulating the future climate change scenarios in 2050. The niche models predicted a reduction in climatically suitable areas for wheat, and identified "maximum temperature" as the most influencing factor for area reduction. The elevated CO₂, O₃, and temperature individually and in combinations had differential impacts on the yield of wheat cultivars. Only two cultivars, viz., DBW 184 and DBW 187 did not exhibit yield decline suggesting their suitability in the future climate change scenario. Since the performance of six out of eight cultivars significantly declined under simulated FACE experiment, and ENM predicted reduction in wheat cultivation area under RCP 8.5 in 2050, it was concluded that future of wheat cultivation in India is bleak. The study further indicates that coupling of bioclimatic modeling and FACE experiment can effectively predict the impact of climate change on different crops.