Susceptibility of global crop production to climate variability and change

For millennia, humans have grown their food in relatively stable Holocene climatic conditions, which are now perturbed by anthropogenic climate change. Weather is an inseparable part of food production, and floods, droughts, and heatwaves remain a nuisance to farmers around the globe. Approximately, a third of global crop yield variability is caused by climate variations with even higher sensitivities reported for maize and wheat, both highly important global food commodities. Hence, a comprehensive understanding about the impacts of climate variability and change on global crop production is imperative to ensure a sufficient and stable food supply for the growing global population. Although the threats posed by climate change are widely acknowledged and researched, the extent of global food crop production at risk of experiencing novel climatic conditions due to climate change has not yet been quantified. Climate change is also projected to increase the frequency of extreme weather events. However, it remains unclear how these changes will relate to agriculture. For example, it is not fully understood how co-occurring extremes impact crop yields, and whether there have been any historical changes in their probability. Interannual variations in climatic conditions are also partially driven by climate oscillations. Predictions about their status could potentially provide useful information for preparing against adverse weather. However, this would require more detailed understanding about their relationship with crop productivity. This dissertation reveals that climate change might push up to a third of global food crop production to unprecedented climatic conditions if nations continue to increase their greenhouse gas emissions. Further, it finds that weather extremes often reduce crop productivity, with co-occurring heat and drought leading to the largest impacts. Alarmingly, the probability of hot and dry weather has increased in recent decades, especially during the wheat growing season for example in Europe and North America. Finally, this dissertation finds that large-scale climate cycles, such as the El Niño Southern-Oscillation, influence agriculture across all continents that produce crops, with strong impacts observed, for example, in many parts of Australia, Africa, and South America. Climate change has already affected global crop production; future solutions should therefore concentrate on increasing the resilience of farming systems to anomalous weather, in addition to mitigation actions. Development of early warning systems, and agricultural monitoring as well as improving water and soil management with, for example, irrigation and conservation agriculture could provide viable options to manage these increased climatic risks.