Contents lists available at ScienceDirect Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet Climate change impact on Mexico wheat production Ixchel M. Hernandez-Ochoa a , Senthold Asseng a, ⁎ , Belay T. Kassie a,b , Wei Xiong a,d , Ricky Robertson c , Diego Notelo Luz Pequeno d , Kai Sonder d , Matthew Reynolds d , Md Ali Babar e , Anabel Molero Milan d , Gerrit Hoogenboom f a Department of Agricultural and Biological Sciences, University of Florida, FL 32611, USA b DuPont Pioneer, 8650 NW 62nd Avenue, Johnston, IA, 50131, USA c International Food Policy Research Institute, Washington, DC, 20006-1002, USA d International Maize and Wheat Improvement Center, Apdo. Postal 6-641, 06600, D.F, Mexico e Department of Agronomy, University of Florida, FL, 110965, USA f Institute for Sustainable Food Systems, Frazier Rogers Hall, University of Florida, Gainesville, FL, 32611, USA ARTICLE INFO Keywords: Triticum Model ensemble Crop simulation model Uncertainty ABSTRACT Wheat is one of the most important cereal crops in Mexico, but the impact of future climate change on pro- duction is not known. To quantify the impact of future climate change together with its uncertainty, two wheat crop models were executed in parallel, using two scaling methods, five Global Climate Models (GCMs) and two main Representative Concentration Pathways (RCPs) for the 2050s. Simulated outputs varied among crop models, scaling methods, GCMs, and RCPs; however, they all projected a general decline in wheat yields by the 2050s. Despite the growth-stimulating effect of elevated CO 2 concentrations, consistent yield declines were simulated across most of the main wheat growing regions of Mexico due to the projected increase in tempera- ture. Exceptions occurred in some cooler areas, where temperature improved sub-optimal conditions, and in a few areas where rainfall increased, but these increases only provided negligible contributions to national pro- duction. Larger and more variable yield declines were projected for rainfed wheat due to current and projected spatial variability of temperature and rainfall patterns. Rainfed wheat, however, only contributes about 6% of Mexico’s wheat production. When aggregating the simulated climate change impacts, considering temperature increase, rainfall change, and elevated atmospheric CO 2 concentrations for irrigated and rainfed wheat cropping systems, national wheat production for Mexico is projected to decline between 6.9% for RCP 4.5 and 7.9% for RCP 8.5. Model uncertainty (combined for crop and climate models) in simulated yield changes, and across two scaling methods, was smaller than temporal and spatial variability in both RCPs. Spatial variability tends to be the largest in both future scenarios. To maintain or increase future wheat production in Mexico, adaptation strategies, particularly to increasing temperatures affecting irrigated wheat, or expanding the cropping area, will be necessary. 1. Introduction Wheat is one of the major cereal crops in the world because of its importance as a main source of energy and protein in human diets (Curtis et al., 2002). In Mexico, wheat is among the top five produced crops: national production during the 2015–2016 season was 3.8 mil- lion tons (around $750 million value), cultivated on 720,000 ha (SAGARPA, 2016b). Production is concentrated in Sonora, Baja Cali- fornia, Sinaloa, Guanajuato, and Michoacán states, which together re- present about 86% of the total national production (SAGARPA, 2016a). More than 90% of the produced wheat is irrigated due to the arid and semi-arid climate in most of the wheat production area. Rainfed wheat production is typical of the high elevation areas in the central and southern states and Mediterranean-type climate in Baja California, where winter and spring temperature and rainfall are more suitable for the cropping system (Escobar, 2014). Past global temperature trends already show the effects of warming temperatures on wheat production. Historical wheat yield analysis showed a 5.5% global decline in aggregated wheat production since 1980, as a result of increased global mean temperature (Lobell et al., 2011). In Mexico, Asseng et al. (2014) reported warming decadal trends in Obregon (Sonora) and Toluca (Mexico State) of 0.46 and 0.27 °C, https://doi.org/10.1016/j.agrformet.2018.09.008 Received 16 March 2018; Received in revised form 7 September 2018; Accepted 10 September 2018 ⁎ Corresponding author. Current address: Department of Agricultural and Biological Sciences, University of Florida, FL 32611, USA. E-mail address: sasseng@ufl.edu (S. Asseng). Agricultural and Forest Meteorology 263 (2018) 373–387 0168-1923/ © 2018 Elsevier B.V. All rights reserved. T