Impact of climate change on Swedish agriculture: Growing season rain deficit and irrigation need

Abstract

Over 90% of Swedish agriculture is rainfed, and thus future climate change can pose a risk to agricultural production in coming decades. An overall increase in annual precipitation is predicted for northern Europe, but Sweden could still face an increasing need for irrigation, as shown by the drought summer of 2018. Adaptation of Swedish agriculture to include irrigated agriculture should thus be considered. To evaluate the theoretical need for irrigation, calculations were performed for different locations in Sweden, and for different soil-crop pairs at each location. In-situ weather data from a projected climate dataset created by the Swedish Meteorological and Hydrological Institute were used to evaluate changes in irrigation need over the period 1981–2050. The results showed an increasing need for irrigation of cereal crops during the early season (May–June), for two main reasons: i) A shift to an earlier start of the cropping period, leading to an earlier need for irrigation; and ii) a higher probability of dry spring weather, substantially increasing the irrigation requirement in dry years. Crops for which the growing season starts later (e.g., potatoes) showed an increasing need for irrigation during July. Crop development stages were predicted to occur earlier, leading to earlier harvesting, reducing the irrigation requirement in August. However, the calculation approach developed for this study may have underestimated the need for irrigation, which could be higher than reported here.