Over Half of the Negative Crop Yield Variability Explained by
Anthropogenic Indicators
Abstract
High crop yield variation between years, impacted for example by extreme
weather shocks and by other shocks on the food production system, can
have substantial effect on food production. This, in turn introduces
vulnerabilities within global food system. To mitigate the effects of
these shocks there is a clear need for understanding how different
adaptive capacity measures link to the crop yield variability. While
existing literature provides many local scale studies on this linkage,
no comprehensive global assessment yet exists. We assessed reported crop
yield variation for wheat, maize, soybean and rice for time period
1981-2009 by measuring both yield loss risk (variation in negative yield
anomalies considering all years) and changes in yields during only dry
shock and hot shock years. We used machine learning algorithm XGBoost to
assess globally the explanatory power of selected gridded anthropogenic
indicators (i.e., adaptive capacity measures; such as Human Development
Index, irrigation infrastructure, fertilizer use) on yield variation on
0.5 degree resolution, within climatically similar regions to rule out
the role of average climate conditions. We found that the anthropogenic
indicators explained 40-60% of yield loss risk variation whereas the
indicators provided noticeably lower (5-20%) explanatory power during
shock years. On continental scale, especially in Europe and Africa the
indicators explained high proportion of the yield loss risk variation
(up to around 80%). Assessing crop production vulnerabilities on global
scale provides supporting knowledge to target specific adaptation
measures, thus contributing to global food security.