摘要：Many countries in the Global South depend increasingly on imports to provide food for their rising populations. Trade is a key mechanism to address distributional issues, especially in countries with limited biophysical resources. In theory, by pooling the risk of crop failures via global trade, trade should stabilize food supplies. In practice, however, an over-reliance on imported food may be detrimental to domestic food stability. Here, we disentangle the role of imports from that of domestic production in countries in the Global South for three staple crops: maize, rice, and wheat. First, we use FAO data to differentiate between exposure to production variance in exporting countries, domestic production variance, and total supply variance. Next, we analyze trade relationships and assess the biophysical capacities of countries to investigate why some countries have more unstable supplies than others. We find that food imports have been a source of food supply instability - in particular for maize in Southern Africa, wheat in Central Asia, and rice more generally. But the reason that imports lead to instability is not the same across regions or crops and imports are at times necessary due to limited available water and land resources. Furthermore, the source of imports may be important in the case of co-occurring crop failures in both importing and exporting countries, or exporters with high export variance. Finally, we find that the increasing prevalence of global trade from 1985-2010 has increased exposure to food supply variance in some regions, although it has not increased exposure to supply variance in all regions. These results provide guidance for future analyses to focus on regions that are vulnerable to imported food supply disruptions of important staple crops, and inform debates about the risks associated with food trade in the Global South.
