Impact of climate change on the bioclimatic suitability of different Portuguese grape varieties in Europe

Viniculture has a long tradition in southern Europe and is an important socioeconomic sector in many countries. Temperate climates allow for this activity, as moderate temperatures and precipitation are key to the proper phenological development of grape vines. However, the onset of climate change has led to increasingly higher temperatures and changing precipitation regimes during the growing season in the last decades. According to the latest report by the Intergovernmental Panel on Climate Change, a continuation of the observed changes is expected in the coming decades, independently of the radiative forcing scenarios that are considered. Wine quality has already been affected in some regions, but the long-term sustainability of wine growing itself is now in question. To better understand what the future could look like, the bioclimatic suitability of Portugal, Spain, France, and Italy for twelve Portuguese grape varieties was modeled using the R BIOMOD2 platform. Ensemble correlative models were made using the current locations of the grape varieties in Portugal and the bioclimatic indexes "Huglin Index", "Cool Night Index", "Growing Season Precipitation Index", and "Temperature Range during Ripening Index" as predictive variables. The indices were calculated with Copernicus’s E-OBS dataset for the recent past (1989-2005) and the EURO-CORDEX datasets for the future (2051-2080), considering the Representative Concentration Pathways 4.5 and 8.5. The models obtained high scores in the evaluation of their predictive performance (ROC > 0.9) and allowed for the identification of the most suitable regions for the different grape varieties across the study area. A clear shift in bioclimatic suitability towards the north was observed, namely towards the north of Spain and France, and in some cases, also towards regions with higher elevation. These shifts were mainly due to the projected overall rise in thermal accumulation and lower precipitation in the southern regions, which is corroborated by the evaluation of the contribution of each of the indexes to the models. Thus, the long-term sustainability of the wine industry in Europe will most likely require measures of adaptation that mitigate the effects caused by the change in these two atmospheric factors.