Evidence for a weakening strength of temperature-corn yield relation in the United States during 1980-2010

The linkage between spatially averaged growing season temperature (GST) and corn yield. (a) and (b) is for the correlation coefficient of GST and corn yield for the first 15 years and the last 15 years, (c) and (d) is for the sensitivity of corn yields to one degree increase of temperature (%/K). The partial correlation is conducted for controlling the effects of precipitation and radiation. All variables are detrended for the corresponding period. * and **denote the significant correlation at P < 0.05 and P < 0.01, respectively.68