The phenological phases of early and mid-late budbreak olive cultivars in a changing future climate over the Euro-Mediterranean region

Future climate changes will likely alter the length and timing of phenological phases of olive crop. The timing and management of agronomic practices (planting, irrigation, fertilization, crop protection, harvesting, etc.) are based on phenological phases and plant development. Consequently, accurate phenological assessments are essential to define climate risks and guide optimal management apt to mitigate climate change effects on olive development. This research highlights future changes in olive phenological phases (i.e., sprouting, blooming, and pit hardening) over the Euro-Mediterranean region for both early and mid-late budbreak cultivars. We apply a Chill, Anti-Chill, and Growing Degree Days combined model to project the timing of phenological phases based on an ensemble of high-resolution climate projections at 0.11° from EURO-CORDEX (Coordinated Regional Climate Downscaling Experiment) for historical (1976–2005) and future (2036–2065) periods under three emission scenarios (RCP2.6, RCP4.5, and RCP8.5). The results showed that more than 75 % of the study area would experience significant earlier phenological development for olive by 2050, with 5–10 days earlier relative advancement for RCP8.5 compared to other RCPs. We projected greater olive phenological advances (i.e.,>20 days) within colder areas due to persistent chilling and increasing heating units following future warming condition, indicating climate suitability for olive growth, while the southern Mediterranean is still facing high potential phenological disturbance induced by advances of 10–25 days. Future differences in phenological earliness between the cultivars (5–15 days) demonstrate the vulnerability of the early cultivar in the Mediterranean despite consistent thermal suitability for the mid-late cultivar in northern Europe and colder zones. Our investigation highlights regional phenological modeling processes relevant to guide strategic management of olive cultivation under future changing climate.