Climate change projections for chilling and heat forcing conditions in European vineyards and olive orchards: a multi-model assessment

Air temperatures play a major role on temperate fruit development, and the projected future warming may thereby bring additional threats. The present study aims at analyzing the impacts of climate change on chilling and heat forcing on European vineyards and olive (V&O) orchards. Chilling portions (CP) and growing degree hours (GDH) were computed yearly for the recent past (1989-2005) and the RCP4.5 and RCP8.5 future scenarios (2021-2080), using several regional-global climate models, also considering model uncertainties and biases. Additionally, minimum CP and GDH values found in 90% of all years were also computed. These metrics were then extracted to the current location of V&O in Europe, and CP-GDH delimitations were assessed. For recent past, high CP values are found in north-central European regions, while lower values tend to exist on opposite sides of Europe. Regarding forcing, southern European regions currently show the highest GDH values. Future projections point to an increased warming, particularly under RCP8.5 and for 2041 onwards. A lower/higher CP is projected for south-western/eastern Europe, while most of Europe is projected to have higher GDH. Northern-central European V&O orchards should still have future CP-GDH similar to present values, while most of southern European orchards are expected to have much lower CP and higher GDH, especially under RCP8.5. These changes may bring limitations to some of the world most important V&O producers, such as Spain, Italy and Portugal. The planning of suitable adaptation measures against these threats is critical for the future sustainability of the European V&O sectors.