Feeding humanity through global food trade
The recent intensification of international trade has led to a globalization of food commodities and to an increased disconnection between human populations and the land and water resources that support them through crop and livestock production. Several countries are not self sufficient and depend on imports from other regions. Despite the recognized importance of the role of trade in global and regional food security, the societal reliance on domestic production and international trade remains poorly quantified. Here we investigate the global patterns of food trade and evaluate the dependency of food security on imports. We investigate the relationship existing between the trade of food calories and the virtual transfer of water used for their production. We show how the amount of food calories traded in the international market has more than doubled between 1986 and 2009, while the number of links in the trade network has increased by more than 50% Likewise, global food production has increased by more than 50% in the same period, providing an amount of food that is overall sufficient to support the global population at a rate of 2700 3000 kcal per person per day. About 23% of the food produced for human consumption is traded internationally. The water use efficiency of food trade (i.e. food calories produced per unit volume of water used) has declined in the last few decades. The water use efficiency of food production overall increases with the countries' affluence; this trend is likely due to the use of more advanced technology.