Modeling water demand for crop irrigation in Sweden under climate change

The study encompasses Sweden (450 000 km 2 ) located on the Scandinavian Peninsula in northern Europe. We quantified the future crop-water demand and water-irrigation needs of 30,000 km² arable land across Sweden to prepare for climate adaptation. We applied a spatially distributed catchment-scale (40,000 sub-basins) hydrological model with an irrigation routine according to FAO guidelines. The model was forced with an extensive ensemble of bias adjusted regional climate-model data to explore climate impact. Compared to the rest of the world, Scandinavia is a region with sparse irrigation and lack of data on crop-water demand, despite the rising concerns among practitioners. For the first time, we quantified the needed increase in irrigation water to preserve current crop cultivation under climate change. End-of-century projections indicate average annual irrigation-water demand of 905 and 1239 million m³ under the mid- and high-emission scenarios, corresponding to 58% and 116% of Sweden’s current freshwater use which is a significant increase from 3% today. The driest years were not found significantly drier but rather more frequent, and at worst, an average year might become as dry as the driest year in 1981–2010. Hence, because of global warming, Sweden may shift from rainfed to more irrigated crop production. This would increase agricultural production but also reduce water availability for competing sectors and ecological flows. • Agriculture in Sweden might need to shift from rainfed to irrigated crop production. • Already in current climate the water demand is much higher than irrigation levels. • Crops will have more days with water stress, despite an increase in rainfall. • Irrigation may rise from 3% to 58%-116% of Sweden’s current fresh water use by 2100. • Water allocation between various sectors will be needed for sustainable management.