Updated climate change impacts for viticulture in the Douro Winemaking Region

Climate change is expected to bring significant transformations to viticultural systems in long-established wine regions, including the Douro Wine Region (DWR) in northern Portugal. In this work, the influence of projected climate conditions on major viticultural indicators, namely grape yield, timing of phenological stages, and potential alcohol levels, is assessed through an ensemble of high-resolution downscaled climate projections. Future conditions are analysed in comparison with a recent baseline period (1986 to 2015) under two Shared Socioeconomic Pathways: SSP1–2.6 (low emissions) and SSP5–8.5 (high emissions) for the period 2041 to 2070. The results reveal a consistent and statistically significant climate signal for all variables considered, with stronger effects and greater spatial variability under the high-emissions scenario. Model projections indicate a widespread reduction in yields across the DWR, typically ranging from about −1 to −3 t ha⁻¹, with the largest decreases occurring in areas that currently have the highest productivity, particularly in the Douro Superior subregion. This pronounced spatial differentiation points to increased regional susceptibility and underscores the need for location-specific adaptation strategies. The phenological response shows a clear shift toward earlier flowering, advancing by as much as roughly 30 days compared with the reference period, especially under SSP5–8.5. Such changes are expected to modify grape development patterns, increase the risk of exposure to late frost during early growth stages, and challenge existing vineyard management schedules. At the same time, potential alcohol content is projected to rise throughout the region, in some places surpassing an increase of +2% vol under the high-emissions scenario. This trend may affect wine style and typicity, complicate compliance with appellation regulations, and create new demands for harvest timing and winemaking practices to control sugar accumulation. These projections indicate that climate change will drive marked and spatially uneven shifts in Douro viticulture. Although the low-emissions pathway limits the severity of these impacts, the outcomes associated with SSP5–8.5 highlight the urgency of implementing forward-looking adaptation measures to safeguard wine quality, economic sustainability, and the cultural identity of the region.