Jul 5, 2017

Wheat yield loss attributable to heat waves, drought and water excess at the global, national and subnational scales

M Zampieri, A Ceglar, F Dentener and A Toreti
Environmental Research Letters
  • States that heat waves and drought are often considered the most damaging climatic stressors for wheat
  • Characterizes and attributes the effects of these climate extremes on wheat yield anomalies (at global and national scales) from 1980 to 2010
  • Uses a combination of up-to-date heat wave and drought indexes (the latter capturing both excessively dry and wet conditions)
  • Develops a composite indicator that is able to capture the spatio-temporal characteristics of the underlying physical processes in the different agro-climatic regions of the world
  • Finds that the diagnostic explains a significant portion (more than 40%) of the inter-annual production variability at the global level 
  • Quantifies the contribution of national yield anomalies to global fluctuations
  • Finds that just two concurrent yield anomalies affecting the larger producers of the world could be responsible for more than half of the global annual fluctuations
  • Finds that the relative importance of heat stress and drought in determining the yield anomalies depends on the region; moreover, in contrast to common perception, water excess affects wheat production more than drought in several countries
  • Performs the same analysis at the subnational level for France, which is the largest wheat producer of the European Union, and home to a range of climatic zones
  • Finds that large subnational variability of inter-annual wheat yield is mostly captured by the heat and water stress indicators, consistently with the country-level result