Heat subtly influences the volatile compounds in wine, which evaporate to form its distinctive aroma. These compounds tend to degrade under higher temperatures, shifting towards what experts describe as a ‘cooked’ aroma—think jammy or like cooked fruit. According to Gambetta, this change can be appealing to some, reflecting the unique identity of a wine region.
The quintessential climate for vine cultivation involves warm days followed by cool nights, a cycle that allows grapes to mature perfectly. However, climate change is disrupting this balance significantly. “It’s the nights that are warming more rapidly than the days,” Forrestel points out, highlighting that the lack of nocturnal cooling and excessive daytime temperatures degrade crucial compounds in the grapes.
Even without drought, elevated temperatures cause plants to lose more water, diminishing grape yields and, consequently, the volume of juice available for winemaking. This situation is exacerbated by drought, leading to even lower yields. “In Bordeaux, where I work, rainfall has remained relatively constant over the last century,” Gambetta notes. “Yet, the rising temperatures are increasing water consumption in agriculture.”
Moreover, vineyards can suffer from excessive water. A warmer atmosphere holds more moisture, fueling more intense rainstorms and leading to catastrophic flooding worldwide. Excessive rainwater can suffocate vine roots by depriving them of oxygen.
Despite these challenges, grapevines are remarkably resilient. Varieties like grenache, typical of the Mediterranean, can produce satisfactory yields and quality wines with minimal rainfall. Vines may survive droughts with reduced yields or by shedding leaves, a process known as defoliation, and recover once the rains return.
However, climate change is making droughts more frequent and severe, putting pressure on winemaking regions. “In 2022, an extreme year in Europe, particularly in Portugal and parts of Spain, vines were severely stunted and defoliated,” Gambetta recalls, warning of the potential for not only immediate but also long-term detrimental effects.
To cope, vineyards might resort to irrigation, which incurs additional costs and could strain local water resources, especially during droughts. Moreover, plants still have to withstand the increasing frequency of heatwaves in Europe.
Alternatively, vineyards could migrate northward as the climate warms. A recent study suggests that suitable land for winemaking in northern Europe and North America could expand by 80 to 200 percent, depending on future warming levels. Notably, winemaking is flourishing in southern UK, Oregon, and Washington state in the US, highlighting a potential shift in the industry’s geographical landscape.