Spatiotemporal patterns of cardinal thermal threshold exceedance in European agriculture

Agricultural production across Europe is highly sensitive to temperature, yet most continental-scale assessments still provide limited insight into when cardinal temperature thresholds are exceeded during the growing season and where the resulting thermal stress is most pronounced. Here, we present a growing-stage-resolved assessment of thermal exposure across the European agricultural growing season using potato cardinal temperatures. over 1990–2020. Using daily ERA5 land 2-m air temperature, we defined three region-specific growing windows (Southern: February–June; Central: April–September; Northern: May–August) and divided each season into four phenological stages based on FAO recommendations. Within these windows, seven Thermal Threshold Classes (TTCs) were defined representing conditions ranging from drastic cold to drastic heat, including the optimal range for potato growth 18-20 °C. Long-term mean patterns reveal a clear spatial variation: cold categories dominate in Nordic and high-elevation regions, whereas heat-related categories are concentrated in Mediterranean areas and coastal lowlands. Trend analysis using the Mann–Kendall test indicates widespread declines in cold exposure across Northern and Central Europe, alongside increasing mild and severe heat exposure in Central and Eastern Europe. Stage-dominance maps further highlight that early-season cold exposure remains widespread in northern regions, while late-season heat expands across Mediterranean and eastern areas, raising the likelihood of heat stress during tuber initiation and bulking. Overall, the results show that European agriculture is undergoing a measurable redistribution of thermal risk, with reduced early-season cold constraints but increasing late-season heat pressure in key production regions. These stage-specific thermal metrics provide a practical basis for identifying emerging hotspots and supporting targeted adaptation strategies in European potato systems.