text: First maize yields across the world during the historical period 1986–2005 were simulated at the 0.5° × 0.5° 
  grid scale with two main production systems, including Spring maize and Summer maize. Historical national 
  maize production is aggregated from simulated gridded yield and weighted by grid cell maize areas in 2000 from 
  the gridded global dataset by combining two data products47. Second, genetic parameters of specific cultivars of 
  maize from previous works were adopted for the initial parameters; model parameters related to crop genotype 
  characteristics were calibrated and tuned following the method in Xiong et al.52, in which the simulated yields 
  from 1986–2005 were comparable to the statistical data. Third, maize yields across the world were simulated 
  under global warming by 1.5 °C and 2.0 °C. Finally, global and national maize yields were aggregated from grid- 
  ded values; changes in national and global yields under global warming by 1.5 °C and 2.0 °C were calculated, 
  comparing maize yield average for 1986–2005. 