Modeling agricultural water deficit risk in finland under CMIP6 climate scenarios

Abstract Understanding the spatial and temporal evolution of water deficits is critical for assessing the sustainability of Finnish agriculture under climate change. This study quantified historical and projected water deficit volumes and deficit days across Finland using a daily water balance model, driven by observational data from the Finnish Meteorological Institute (FMI, 1981–2014) and future projections from the CMIP6 ensemble under SSP2-4.5 and SSP5-8.5 scenarios (2015–2100). Historical consistency between FMI- and CMIP6-ENS-derived deficit indicators was evaluated using multiple metrics, including r, MAE, RMSE, and NRMSE, showing moderate-to-strong agreement in broad spatial water-deficit patterns. Historically, annual water deficit volumes have ranged from 90 to 150 mm, peaking in southern and western croplands, with deficit days averaging 40–55 per year. Under SSP2-4.5, national deficit volumes increased moderately from 131 mm (2026) to ~153 mm (2100), while under SSP5-8.5, they rose sharply to over 220 mm, with southern Finland reaching 234 mm by century’s end. Similarly, deficit days expand from 48 to 50 under SSP2-4.5 and to 61 under SSP5-8.5, with southwestern regions showing the most pronounced changes. These results highlight increasing water stress, particularly beyond 2050, suggesting growing risks for crops such as potatoes. Adaptation measures, including improved irrigation efficiency, drought-tolerant cultivars, and shifts in cultivation to the north, are essential to sustain productivity under future climate regimes.