Climate change will impose increasingly warm and dry conditions on vineyards. Wine quality and yield are strongly influenced by climatic conditions and depend on complex interactions between temperatures, water availability, plant material, and viticultural techniques. In established winegrowing regions, growers have optimized yield and quality by choosing plant material and viticultural techniques according to local climatic conditions, but as the climate changes, these will need to be adjusted. Adaptations to higher temperatures include changing plant material (e.g., rootstocks, cultivars and clones) and modifying viticultural techniques (e.g., changing trunk height, leaf area to fruit weight ratio, timing of pruning) such that harvest dates are maintained in the optimal period at the end of September or early October in the Northern Hemisphere. Vineyards can be made more resilient to drought by planting drought resistant plant material, modifying training systems (e.g., goblet bush vines, or trellised vineyards at wider row spacing), or selecting soils with greater soil water holding capacity. While most vineyards in Europe are currently dry-farmed, irrigation may also be an option to grow sustainable yields under increasingly dry conditions but consideration must be given to associated impacts on water resources and the environment.

Climate is a major factor of the physical environment influencing terroir expression in viticulture. Thermal conditions strongly impact vine development and grape composition. Spatializing this parameter at local scale allows for more refined vineyard management. In this study, temperature variability was investigated over an area of 19,233 ha within the appellations of Saint-Émilion, Pomerol, and their satellites (Bordeaux, France). A network of 90 temperature sensors was deployed inside grapevine canopies of this area and temperatures were measured from 2012 through 2018. To determine the effect of temperature on vine development, the phenological stages (budbreak, flowering, and véraison) were recorded on 60 reference plots planted with Vitis vinifera L. cv. Merlot located near the temperature sensors. Results showed great spatial variability in temperature, especially minimum temperature, with an amplitude of up to 10°C on a given day. The spatial variability of the Winkler index measured in the canopy inside a given vintage was around 320 degree-days. This research explores the main factors affecting spatial variability in temperature, such as environmental factors and meteorological conditions. The impact of temperature on vine behavior was also analyzed. Observed phenological dates were compared to those estimated using the Grapevine Flowering Véraison model. Maps of temperatures and phenological observations were created over this area and provided a useful tool for improved adaptation of plant material and training systems to local temperature variability and change.

Given the important role of temperature in vine development and grape composition, climate change has already impacted wine production. Adaptation strategies are needed in order to sustain the production of wines and maintain their typicity. Several levers of adaptation are possible, including the use of more heat and drought tolerant plant material, relocating the vineyard and adaptations in the cellar. The training system is also a potential lever for adaptation that is relatively easy to implement. Taking that avenue, a study of the vertical thermal gradient in the vine canopy was carried out in order to determine whether trunk height could be an adaptation strategy for manipulating micro-climate in the bunch zone. Temperature was measured at four different heights from the soil (30, 60, 90 and 120 cm) in two adjacent vineyard parcels. One parcel was managed with cover crop and the other by tilling the soil. The results of this study show that increased trunk height is not likely to significantly delay ripeness, but it could minimise the potential damages of both frost and heat wave events. Type of parcel management was found to have an effect: close to the ground, the cover crop parcel generally had lower minimum temperatures and higher maximum temperatures in comparison to the tilled parcel, exposing the vines to an increased risk of both frost and heat wave damage. When investigating the factors driving the vertical thermal gradient, soil moisture and weather type were found to have an impact. Some of these factors, like mean temperature and soil moisture, may exacerbate the vertical temperature gradient of maximum temperature in a climate change context and increase the risk of damages due to extreme temperatures.

The final sugar concentration in grapes is an important parameter for winegrowers as it determines the alcohol content by volume of the final wine, allowing the timing of harvest to be optimised. In this research, a comprehensive dataset spanning seven years and 18 sites located in Saint-Émilion, Pomerol and satellite appellations (Bordeaux, France) was used to assess how growth and developmental factors (berry weight and mid-veraison date, respectively) and environmental factors (vine water status, nitrogen status, and mean air temperature) influence the dynamics of sugar accumulation. The results of this study highlight the strong influence of mean temperature on the timing of maximum sugar accumulation, the duration of sugar accumulation and maximum sugar concentration in grape berries. Berry weight and the rate of sugar accumulation also appeared to be significant drivers of final sugar concentration. Fast ripening and increased berry weight were associated with lower sugar concentrations. Sites were clustered according to parameters driving sugar accumulation dynamics and mapped at the scale of the study area, in order to link these findings to terroir expression. In this study, vine nitrogen status did not emerge as a significant explanatory variable in any of the models developed to analyse sugar accumulation dynamics and berry weight. A small but significant effect of vine water status on the precocity of the plateau and on berry weight was found. These results provide a better understanding of the factors that affect the dynamics of sugar accumulation in grape berries, which can help vine growers adapt to climate change. For example, by promoting practices that delay the onset of ripening to shift to a cooler period of ripening through choice of plant material and management practices. Alternatively, this can be done through an increase in berry weight, which lowers grape sugar and therefore wine alcohol concentration, taking care not to excessively alter the skin-pulp ratio to avoid reducing secondary metabolites.

Temperature is a key factor in vine growth and grape composition (Jones, 2006). Climate change is already having an impact on these parameters in many wine regions, and it is becoming necessary to adapt in order to continue producing quality wines, without strongly altering their typical character (van Leeuwen et al., 2019). One way to adapt could be to modify the vine’s training system. A study of temperature at different heights was carried out in the Bordeaux region to assess whether increasing trunk height could modify the microclimate in the bunch zone (de Rességuier et al., 2023).