Climate change and Australian wheat yield

Abstract

Nicholls¹ reported that 30-50% of the increase in Australian wheat yields in the period 1952-92 resulted from climate change. He estimated a simple linear relationship where a 1°C fall in diurnal temperature range increased Australian wheat yield by 0.52 t ha⁻¹. This effect, taken with the trend in diurnal range, accounted for 45% of the yield increase between 1952 and 1992. In an extended model with three climate variables, Nicholls found that changes in minimum temperature had had most impact on wheat yield and that rainfall change had contributed little. In our view, Nicholls's results need qualification and should be interpreted with caution. They are only estimates, and do not include standard errors to indicate their precision.