Response of viticulture-related climatic indices and zoning to historical and future climate conditions in Greece

Climate and viticulture are indisputably linked and thus knowledge of the predominant weather and climate conditions of a given area is essential for optimum variety selection, viable production and overall wine quality. In this study, an assessment of the current (1981-2010) and future conditions (2021-2050 and 2061-2090) through principal climatic elements and six bioclimatic indices (i.e. Growing season average temperature, growing degree-days, Huglin index, biologically effective degree-days, dryness index and cool night index) at 23 weather stations proximal to the key mainland, coastal and island viticultural areas of Greece was performed. Mainland locations were generally colder due to their wider variety of terroir aspects and elevation, while coastal locations and islands faced proportionally more extreme temperatures and drier conditions. Trend analysis revealed that minimum temperatures increased at higher rates than the respective maximum temperatures at most locations. Climate change scenarios derived from the regional climate model RegCM4 suggested significant shifts towards warmer and drier conditions across all locations in the future. These conditions are very likely to advance phenology and harvest beyond what is considered suitable and will likely have detrimental impacts on wine quality. Differences in impacts will likely be seen between wine areas currently cultivated with early ripening (reducing variety suitability) versus those with later-ripening (increasing consistency in ripening) varieties. Overall, the changes projected for the future climate will challenge the Greek wine industry to increase its adaptive capacity through better understanding of temperature thresholds for the varieties grown and the adoption of new cultivation techniques and strategies.