The past and future of food stocks

Human societies rely on food reserves and the importation of agricultural goods asmeans to copewith crop failures and associated food shortage.While food trade has been the subject of intensive investigations in recent years, food reserves remain poorly quantified. It is unclear how food stocks are changing andwhether they are declining. In this studywe use food stock records for 92 products to reconstruct 50 years of aggregated food reserves, expressed in caloric equivalent (kcal), at the regional and global scales. A detailed statistical analysis demonstrates that the overall regional and global percapita food stocks are stationary, challenging awidespread impression that food reserves are shrinking. We develop a statistically-sound stochastic representation of stock dynamics and take the stockhalving probability as ameasure of the natural variability of the process.Wefind that there is a 20% probability that the global per-capita stockswill be halved by 2050. There are, however, some strong regional differences:Western Europe and the region encompassingNorthAfrica and theMiddle East have smaller halving probabilities and smaller per-capita stocks, whileNorthAmerica andOceania have greater halving probabilities and greater per-capita stocks than the global average. Africa exhibits low per-capita stocks and relatively high probability of stock halving by 2050, which reflects a state of higher food insecurity in this continent.