A new paper asks, as vineyards get warmer and drier, will familiar grapes such as Chardonnay and Pinot Noir continue to taste recognisably like themselves? The researchers analysed 256 grape-juice samples from 80 vineyards across 13 European and Argentine wine regions over the 2019–2021 vintages, looking at vine water stress and thousands of metabolites.
For the wine drinker, one of the most interesting findings is that water stress is not simply “bad”. Increasing water deficit was associated with changes in hundreds of compounds, including phenolics, antioxidant compounds and glycosidic aroma precursors, compounds stored in grapes that can subsequently contribute to wine aroma. Many of the sensory-related metabolites actually increased as water deficit increased. This gives some biochemical backing to the long-standing idea that a certain amount of vine stress can enhance the character of wine rather than diminish it.
The Chardonnay result is particularly striking. Across the conditions studied, its metabolic response tended to change progressively as water stress increased rather than suddenly breaking down. The researchers found evidence that glutathione and related compounds increased with water deficit. Glutathione is a naturally occurring antioxidant and is important in protecting dry white wines against oxidation, so the implication is that warmer/drier conditions do not necessarily mean Chardonnay becoming less stable or less interesting. The authors suggest Chardonnay possesses relatively strong “phenotypic plasticity”, essentially an ability to adjust its biology to changing conditions without hitting an obvious tipping point.
Pinot Noir is more concerning. Under weak to moderate water stress, its response was broadly similar to Chardonnay. Once the vines moved into severe stress, however, a number of metabolites stopped increasing and began to fall. Some of these appear to be aroma precursors. The authors therefore suggest that Pinot Noir may have a narrower climatic comfort zone, with a possible physiological tipping point under severe drought.
Another useful consumer insight is that “hot/dry region” does not automatically equal “water-stressed wine”. Irrigation made a big difference. Very dry Valle de Uco vineyards in Argentina, for example, experienced only nil/weak to moderate vine water deficits because they were irrigated, whereas dry-farmed Burgundy vineyards ranged all the way from little stress to severe stress. In other words, producer decisions and vineyard management may increasingly be as important as the region printed on the label when assessing how climate affects wine.
The most useful takeaway is therefore that moderate water stress can be part of what creates flavour and terroir expression, and both Chardonnay and Pinot Noir appear more adaptable to a warmer climate than might be assumed. But the response is not limitless. Chardonnay looks capable of changing gradually while remaining relatively resilient; Pinot Noir appears more likely to undergo a sharper stylistic change once drought becomes severe.
