Overview
- A University of Birmingham analysis tracked how the 40% crop and 70% freshwater withdrawal figures spread across 3,693 documents published from 1966 to 2024.
- Only about 1.5% of papers citing the numbers provided original data, and 60–80% of citation paths led to sources without evidence or without the figures at all.
- Using available data, the authors estimate irrigated agriculture contributes roughly 18–50% of global grain and 45–90% of freshwater withdrawals, underscoring large uncertainty.
- The team describes citation dynamics of amplification and transmutation, where non-evidenced sources and repetition turn tentative claims into purported facts.
- The study highlights limits in FAO Aquastat’s imputed data and urges better measurement and locally tailored policy responses as guidance for food and water decisions ahead of COP30.