Key Irrigation Data May Be Flawed

The idea that irrigated agriculture underpins global food and water security—producing 40% of crops and using 70% of freshwater—has become widespread in science and policy. However, these statistics are not empirically supported, according to a new analysis. Arnald Puy and colleagues traced these figures through citations in 3,693 scientific documents published from 1966 to 2024. The authors found that 60–80% of citation paths led to sources without supporting data or that did not contain the claimed numbers. Only approximately 1.5% of cited documents provided original data. When the authors analyzed available data on irrigation's actual impact, the results showed much wider uncertainty ranges: irrigated agriculture produces 18–50% of the world's grain and is responsible for 45–90% of freshwater withdrawals. The analysis revealed that the 40% and 70% figures spread through "amplification," in which sources without data are used, and "transmutation," in which uncertain claims are presented as definitive facts after repeated citation. The most cited basis for the statistics, FAO's Aquastat database, contains limited country coverage with mostly imputed rather than measured values. According to the authors, the wobbly nature of such oft-repeated statistics highlights the need to critically evaluate foundational claims in sustainability science. Regardless of irrigation's global impact, there are no shortage of specific, local irrigation problems to solve, and they can often be approached most fruitfully with place-based solutions.