Future changes of Climate Suitability of Global Rainfed Food Crops under different CMIP6 scenarios

Achieving the second sustainable development goal, Zero Hunger, is challenging due to climate change, weather extremes and an unabated human population growth. The consequent increase in global food demand has put additional pressure on agricultural systems. Understanding spatial crop suitability alterations, yields and calories of the four major staple food crops around the globe is imperative for sustainable agricultural optimization, climate mitigation, and food security. This study uses three downscaled and bias-corrected shared socioeconomic scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) from the latest state-of-art climate models in Coupled Model Intercomparison Project phase 6 (CMIP6) courtesy of Worldclim: an ecological crop requirement model (Eco Crop) and a machine-learning extreme gradient boosting model (XGBoost) to estimate future crop suitability and yields. Our results elucidate a northward spatial shift in climate suitability and shrinkage of optimal crop-growing regions as the unsuitable and marginal areas expand. Notably, more reduction of suitable regions is observed for all the crops under the highest emission and in far-future climate (2061-2100) scenarios as compared to the SSP1-2.6 and during the near-future period (2021-2060). Nevertheless, gain in suitable areas for soybeans and wheat has been observed at high latitudes, while the tropics are projected to experience a significant loss of arable land. The optimal zone for maize is projected to significantly reduce by approximately 75% in all emission scenarios. This translates to a maize yield loss of 17.3%, and 8.5% in near and far-future climate periods respectively under SSP5-8.5 scenario. Spatial consistency shows that most of the suitable and optimal zones for soybeans are currently not been used. This study sheds light on crop production optimization as farmers are advised to shift to more suitable climate regions for a given crop rather than agricultural extensification that triggers desertification. Due to the considerable loss of climate-suitable regions for rainfed agricultural systems, global efforts should be directed to irrigation systems to ensure global food security and peace. Keywords: Eco crop, Climate suitability, CMIP6, Food security, Crop Yield, XGBoost