Groundwater depletion embedded in international food trade
This letter (PDF), published in the journal Nature, discusses the connection between groundwater depletion and global food consumption. Recent hydrological modelling and Earth observations have located and quantified alarming rates of groundwater depletion worldwide. This depletion is primarily due to water withdrawals for irrigation, but its connection with the main driver of irrigation, global food consumption, has not yet been explored. Many food-producing regions rely on the withdrawal of water from non-renewable underground sources, a condition called groundwater depletion for irrigation. When food produced with groundwater depletion is exported, the exporting country is essentially exporting its non-renewable water resources. The letter analyzes regional and crop-specific groundwater depletion data to identify areas of concern. The results show that approximately eleven per cent of non-renewable groundwater use for irrigation is embedded in international food trade, of which two-thirds are exported by Pakistan, the USA and India alone. A vast majority of the world’s population lives in countries sourcing nearly all their staple crop imports from partners who deplete groundwater to produce these crops, highlighting risks for global food and water security. The five crops that contribute most are wheat, rice, sugar crops, cotton and maize. The results could help to improve the sustainability of global food production and groundwater resource management by identifying priority regions and agricultural products at risk as well as the end consumers of these products. The paper recommends measures to address the problem for both importers and exporters. Food producing nations could implement water-saving strategies such as improvements to irrigation efficiency and a shift to more drought-resistant crops, together with irrigation metering and regulation of groundwater pumping. Importing countries could support sustainable irrigation practices in their trade partners.