The past, present, and future of multiple breadbasket failures: constructing a 100-year statistical record to constrain risks

The global food production system is increasingly interconnected, with more people than ever before relying on imported food to meet daily caloric requirements. In this context, the possibility of multiple simultaneous crop failures in major food production regions poses a unique risk to food security. And yet, little is known about how likely such an event is, or what might cause it. Our understanding is constrained, at least in part, by the limited global historical record of crop yields. Here we gather, digitize, quality control, and combine 90-120 year-long time series for wheat and maize yield data, often at subnational scale, in regions covering the majority of modern global breadbaskets, with the exception of Eastern Europe. The aggregate data set will be made publicly available, including the processed and unprocessed data with accompanying sources for all of the original data.

This extensive spatial and temporal coverage allows us to investigate possible trends in the occurrence of multiple breadbasket failures, as well as to understand what causes such failures. Contrary to past results, we find no evidence that multiple crop failures have been increasing in modern breadbaskets over the last 90 years. Here, we define multiple crop failures as the number of breadbasket regions simultaneously affected in the same year by a yield loss larger than 10% at the regional scale. When multiple crop failures do occur, we use our long historical time series to characterize which breadbaskets tend to fail together, and why. We provide quantitative estimates of how strongly modes of climate (the El Niño Southern Oscillation, the North Atlantic Oscillation, and the Indian Ocean Dipole) affect the likelihood of joint crop-failures in major breadbaskets. Finally, we discuss how climate change may affect the hydroclimate of major breadbaskets during crop growing seasons, and whether projected changes might influence the likelihood of multiple crop failures.