Extreme drought can erase enough rain-fed crops to feed 2.1 billion people

Extreme drought can cut yields of rain-fed crops by as much as 10.1% and remove enough food to meet the needs of 2.1 billion people, according to a study published in Nature Communications that introduces a new indicator to measure how vulnerable crops are to water stress.

The research, led by Marta Tuninetti of the Polytechnic University of Turin and Kyle Frankel Davis of the University of Delaware, presents the Ds indicator, short for Drought Sensitivity. It measures how much crop yields fall in unfavorable climate conditions compared with a normal year. The authors said the tool fills a gap in agricultural research by offering a detailed view of how different crops respond to drought in specific growing areas around the world.

The analysis draws on global climate data from 1961 to 2018, including rainfall, evapotranspiration, soil characteristics and high-resolution agricultural statistics. It examines 17 crops that account for 75% of global production.

The study found a sharp divide between irrigated and non-irrigated farming. Irrigated crops, supported by artificial water supply, were able during drought periods to maintain yields and in some cases even increase them. Rain-fed crops, which depend only on natural precipitation, were far more exposed to extreme weather.

Among the crops studied, soybeans showed drought vulnerability of 15.2%, followed by potatoes at 13.5% and rapeseed at 12.6%. Millet, peanuts and yams were more stable in dry years, with vulnerability levels of 6.8%, 6.2% and 2.8%, respectively.

The researchers also mapped drought-sensitivity hotspots where climate conditions and crop traits combine to raise the risk of losses. Those areas include parts of the central United States, where soybeans, barley and sorghum are especially vulnerable; eastern Brazil, with potatoes, cassava and sugar cane; parts of China, where barley, oil palm and potatoes are more sensitive while rice appears more resilient; and the Mediterranean basin, which the study identifies as one of the world’s most critical regions.

Within the Mediterranean, eastern Spain, Morocco and Algeria stand out as areas where rapeseed, potatoes, wheat and barley face elevated exposure. The authors said identifying these hotspots can help governments and international organizations direct adaptation policies and public investment toward places where action is most urgent and likely to reduce losses.

The study argues that two measures could have a large effect: expanding irrigation where it is sustainable and replacing more sensitive crops with more resilient ones. Combined, those strategies could reduce losses by more than 60% and raise average yields by as much as 14%, according to the authors.

Tuninetti said the work offers a more precise understanding of which crops are most sensitive to drought in different parts of the world. She said researchers and policymakers can use the framework to test large-scale responses and estimate their benefits, with the goal of stabilizing and increasing global agricultural supply.

The findings matter for beverage producers because many drinks depend on farm commodities that are exposed to drought risk. Barley is central to beer production, sugar cane is used in rum and sweeteners for soft drinks, and grain supply pressures can also affect spirits and food-linked beverage chains. In Mediterranean farming regions that support wine production, broader water stress may also intensify pressure on land use and irrigation decisions even when grapes were not among the crops assessed in this study.

The paper places its findings in a wider shift in global agriculture since the 1960s. World food production has tripled over that period, largely through the spread of a limited number of high-yield crops such as rice, corn and wheat. The authors said that growing specialization has made many farming systems less diverse and, in some cases, more vulnerable to climate shocks such as drought.