Multiple breadbasket failure is a risk to global food security. However, there are no global analyses that have quantitatively assessed if global crop production has actually tended towards synchronized failure historically. We show that synchronization in production within major commodities such as maize and soybean has declined in recent decades, leading to increased global stability in production of these crops. In contrast, synchrony between crops has peaked, making global calorie production more unstable. Under the hypothetical event of complete synchronized failure we estimate simultaneous global production losses for rice, wheat, soybean and maize to lie between -17% and -34%. We find that offsetting these losses by reducing variation in production across all growing locations, and raising production ceilings in breadbaskets, are far more effective than strategies focused on reducing variability in breadbaskets alone or closing production gaps in low productive locations. Our findings suggest that maintaining asynchrony in the food system requires a central place in discussions of future food demand under mean climate change, population growth and consumption trends.