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 unstable domestic supplies. We find that food imports have been a source of food supply instability in the Global South — 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, e.g. imported rice, 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 for all crops. These results provide guidance for future analyses to focus on regions that are vulnerable to imported food supply disruptions of staple crops, and inform debates about the risks associated with food trade in the Global South.

中文翻译：

---

国际贸易和全球南方粮食供应的稳定性

全球南方的许多国家越来越依赖进口为其不断增长的人口提供食物。贸易是解决分配问题的关键机制，尤其是在生物物理资源有限的国家。从理论上讲，通过全球贸易来分担作物歉收的风险，贸易应该可以稳定粮食供应。然而，在实践中，过度依赖进口食品可能不利于国内食品的稳定。在这里，我们将全球南方国家三种主要作物（玉米、稻米和小麦）的进口作用与国内生产的作用分开。首先，我们使用粮农组织的数据来区分出口国的生产差异、国内生产差异和总供应差异。下一个，我们分析贸易关系并评估各国的生物物理能力，以调查为什么一些国家的国内供应不稳定。我们发现粮食进口一直是全球南方粮食供应不稳定的根源——尤其是南部非洲的玉米、中亚的小麦和更普遍的大米。但进口导致不稳定的原因因地区或作物而异，有时进口是必要的，例如进口大米，因为可用的水和土地资源有限。此外，在进口国和出口国或出口差异较大的出口国同时发生作物歉收的情况下，进口来源可能很重要。最后，我们发现 1985 年至 2010 年全球贸易的日益盛行增加了某些地区粮食供应差异的风险，尽管它并未增加所有地区所有作物的供应差异风险。这些结果为未来的分析提供了指导，重点关注易受主要作物进口食品供应中断影响的地区，并为有关全球南方食品贸易相关风险的辩论提供信息。