Climate Change Favors Grapevine Production in Temperate Zones
Wine production has a long-standing history in Palatinate (Southwestern Germany), dating back to Roman times. Especially “Riesling”, but also several “Pinot” varieties gained major significance. Red wine varieties gained prominence over the last 20 years only, which may be a consequence of climate change. Our objective was to review temperature and rainfall data over the last 40 years, measured “on-winery” in Hainfeld and correlate these data with grapevine growth parameters: the development of bud break, flowering, veraison and harvest dates, yields and grape sugar concentrations of “Pinot Gris”, “Pinot Noir”, “Riesling”, “Silvaner” and “Müller-Thurgau”. Since the 1970s, bud break, flowering and veraison are 11 - 15, 18 - 22 and 16 - 22 days earlier; harvest dates are 25 - 40 days earlier. Sugar concentrations increased significantly, but yields decreased. Annual rainfall has not significantly risen, while the mean annual minimum and maximum air-temperatures rose by ~0.9˚C, and by ~3.4˚C, respectively, resulting in an average increase of the mean annual temperature of ~2.1˚C. Remarkably, both mean monthly minimum and maximum temperatures rose especially in springtime, which should have been the driver for earlier bud break and flowering. A change in the climatic conditions, therefore, appears to be one of the key reasons for more favorable grapevine production in Palatinate, especially for “Pinot Noir”, which showed the highest increase in sugar concentrations. The Huglin-index, a measure for the suitability of growing specific grapevine varieties in given environments, increased from 1685 to 2063. According to this index, the climate change may be favorable already for growing grape varieties so far rarely grown in temperate zones, such as “Cabernet Sauvignon”, “Syrah” and “Tempranillo” that are more suited to warmer, Mediterranean climates.