Science Source

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

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