Exposure of Portuguese viticulture to weather extremes under climate change

Abstract

Grape berry quality and yield are notably influenced by complex multi-scale interactions between grapevines and local environmental conditions. In established wine-growing regions, bestowing to local climatic conditions, yield and quality are mostly optimized, planting the best wine variety and applying specific cultural practices. Thus, the sustainability of the winemaking sector worldwide is being challenged by ongoing climate change, requiring adaptation at different levels. Climate change will inflict progressively dry and warm conditions on Portuguese vineyards, with changes in frequency and intensity of weather extremes. However, the future projections of these extreme events and their potential impacts on viticulture are less understood. For this purpose, in this study, seventeen climate extreme indices were calculated for the Portuguese wine denomination of origin regions/subregions, in the historical period (1981–2010) and future periods (2041–2070 and 2071–2100), under the Representative Concentration Pathway 8.5, and based on a five-member ensemble of Regional Climate Model-Global Climate Model chain simulations. Furthermore, a principal component analysis was undertaken for both precipitation and temperature extreme indices independently. We found an increase in temperature extremes in all wine regions in Portugal, particularly in the westernmost regions. Regarding the precipitation extremes, they reveal a lessening effect for future periods, accompanied by a generalized decrease of precipitation, but will remain an important threat in the northeastern regions. Conversely, the dry extremes, potentiating severe droughts, will be significantly strengthened. Lastly, it was possible to identify the most exposed and vulnerable wine regions to weather extremes in future climates. This information is critical for supporting decision-making in the sector, namely for long-term planning, climate change adaptation and risk reduction. Practical ImplicationsIn the winemaking sector, resorting to climate information is an effective way of mitigating climate-related risks to attain specific terroirs. To effectively deliver this information to winemakers, climatic vulnerability needs to be identified regionally, in order to promote suitable and locally adjusted measures and policies. In this study, Wine Protected Denomination of Origin (PDO) in Portugal are the key target of the climate (temperature and precipitation) extreme variability between present and future periods. The results provided and synthesized in this study should be able to inform winemakers by identifying potential areas of risk concerning the ongoing climate change and acting accordingly based on the potential occurrence of these climate extremes in each PDO area. Furthermore, some short-term and long-term strategies are presented to mitigate the general increase in temperature and decrease in precipitation.