As Western Europe approaches the end of what is being described as its hottest summer on record, winemakers in some of the world’s best-known wine regions are beginning the harvest earlier than usual.
The shift comes as vineyards face increasingly hot and dry conditions, with some crops also threatened by wildfires and drought.
A new international study has examined how two of the world’s best-known grape varieties, Pinot noir and Chardonnay, could respond to a future in which drought becomes more frequent.
Wine production under drought pressure
Grapevines are generally resilient to water shortages. In some circumstances, a relatively dry year can even improve the quality of red wines, although yields may fall.
Extreme drought, however, can disrupt that balance. Vines produce fewer and smaller grapes, while the fruit may also struggle to ripen properly.
Scientists have proposed developing new grape varieties through selective breeding or gene editing. For historic wine-producing regions in France, Italy and Germany, however, replacing traditional varieties would be particularly difficult.
The reputation and distinctive characteristics of wines from regions such as Burgundy, Campania and the Loire Valley are closely linked to both their geographical origin and specific grape varieties.
Water stress and grape chemistry
To examine how vines could respond to conditions corresponding to a global temperature rise of 2°C above pre-industrial levels, researchers analysed Pinot noir and Chardonnay from 80 vineyards across 13 wine-producing regions in France, Italy, Germany, Portugal and Argentina.
The samples came from the 2019, 2020 and 2021 harvests.
Using carbon isotope analysis of grape juice, the researchers estimated the level of water stress experienced by the vines.
They found that both varieties could tolerate significant water shortages, including conditions corresponding to a climate around 2°C warmer in Burgundy.
Differences emerged, however, when researchers examined the chemical composition of the grapes.
That composition contributes to a wine’s terroir – the distinctive character shaped by the interaction between the grape variety, soil and climate.
Pinot noir shows a possible tipping point
Chardonnay appeared to be more adaptable to increasing water stress.
Even as water shortages intensified, changes in the compounds that determine the variety’s characteristics remained relatively gradual. Researchers found no clear threshold beyond which its quality might change suddenly.
Pinot noir, by contrast, showed a possible tipping point.
Up to a certain level of drought, its chemical composition remained relatively stable. Once water stress became severe, however, important metabolites associated with the wine’s character began to change significantly.
What the findings mean for future wine
The study, published in Food Chemistry: X, suggests that quality Chardonnay could remain viable even as drought becomes more frequent.
Pinot noir may face greater challenges, particularly in traditional growing regions where maintaining the variety’s distinctive characteristics is central to the identity of the wine.
The findings highlight another challenge facing the global wine industry as rising temperatures and increasingly frequent droughts reshape growing conditions.
Also read: Europe faces drought crisis as EU targets 10% efficiency boost
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