Future agroclimatic suitability for oliviculture in Portugal based on a new high-resolution climate dataset

The Mediterranean-type climates on mainland Portugal generally provide suitable conditions for growing olive trees, though climate change may challenge their long-term sustainability. Historical (1995–2014) and projected future scenarios (2041–2060) of agroclimatic indices are developed herein to guide olive orchard (OR) management. Daily simulations from six Global Circulation Models are processed with the CHELSA method, using bias-adjusted ISIMIP3b climate projections based on CMIP6 simulations. Two Shared Socio-Economic Pathways (SSP) are considered: SSP3-7.0 (regional rivalry) and SSP5-8.5 (fossil-fuelled development). Daily data (~ 1 km) are used to calculate the following indices: Consecutive Frost Days (CFD), Spring Heat Day (SPR32), Spring Maximum Temperature (SPRTX), Summer Heat Stress Days (SU40), Total rainfall October–May (WINRR). During the historical period, the North and Centre regions experienced a CFD between 0 and 35, whereas a reduction in CFD up to 9 days and 11 days will be expected under SSP3-7.0 and SSP5-8.5, respectively. In 1995–2014, higher SPR32 (3–12 days) and SPRTX (20–24 °C) are recorded in the inner southern regions, increasing to 24 days and 26 °C, respectively, under SSP5-8.5. In these areas, SU40 could reach 24 days in the future. WINRR will decrease by 100–140 mm (7% of the area), particularly in southern regions. The southern regions will be particularly exposed to high temperatures and low rainfall, while phenological timings and yields may be significantly affected. Adaptation measures, i.e., biostimulants implementation and irrigation strategies definition, could be tools to reduce the impact of climate change on OR. These outcomes can be an important tool for climate change adaptation and risk reduction in the Portuguese olive chain sector.