Abstract

Water footprint assessments of tropical export crops typically rely on long-term climatic averages, overlooking how interannual climate variability reshapes the balance between green and blue water use and limiting their reliability in regions governed by El Niño and La Niña phases. This study hypothesised that such variability modifies the green and blue water components by shifting the balance between rainfall and irrigation. It was tested for banana production in southern Guatemala using 402 farm-year observations across three production zones during 2018–2023, assessing green, blue and grey components across contrasting phases. The total water footprint ranged from 246 to 435 m³/t and differed significantly among zones, while the green contribution rose under wetter phases and theoretical irrigation requirements increased by 25–30% under drier phases. Water footprint composition is therefore climate-phase dependent rather than stationary, making the integration of climate variability essential for reliable benchmarking.