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

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.