Warming climate threatens Europe’s famous red wines

Climate change is putting Europe’s historic wine regions under growing pressure, with the red-wine grape Pinot noir proving less able to withstand severe drought than Chardonnay, ERR reports. French and German researchers found that Chardonnay adapted to water stress more effectively, while Pinot noir’s metabolism failed under extreme drought.

The worsening climate is a serious concern for grape growers in traditional European wine regions. Strict regulations often prevent them from planting more drought-resistant varieties or building larger irrigation systems. In France’s traditional wine regions, growers regard such measures as a last resort, leaving them reliant on vines’ natural ability to adapt during dry years.

The economic and cultural heritage of these regions is at stake. In France and other historic wine-producing areas, the concept of terroir refers to the interaction of the growing location, soil, climate and vine that gives a wine its distinctive character and flavour.

Moderate water shortages can even improve the quality of red wine by concentrating the flavour of the grapes. More extreme heat, however, threatens to permanently disrupt the existing biological balance. Several consecutive dry years can weaken vines and, figuratively, put the identity of an entire region at risk.

Chardonnay adapts better

To assess the situation, the researchers analysed the juice of nearly 260 grapes grown outdoors. The team collected samples from 13 wine regions in Europe and Argentina over three consecutive vintages. They measured the ratio of carbon isotopes in the juice to assess the vines’ water stress at harvest and used laboratory analysis to determine the extent of the plants’ biological strain during heatwaves.

Many of the sampled sites experienced severe water shortages. In Burgundy, for example, temperatures during the 2020 harvest were similar to predictions for a future world that is two degrees warmer than before the industrial era.

The researchers used ultrahigh-resolution mass spectrometry to analyse the molecular composition of the grape juice. The sensitive instrument detected thousands of different metabolic products, or metabolites, in drops of juice.

The chemical data showed that the two globally renowned grape varieties use very different survival strategies. Chardonnay’s metabolism responded steadily and proportionally to drier soil across the entire range of stress. The plants continued functioning even under the driest conditions and smoothly adjusted their biochemistry, which the researchers said indicated that the light-coloured variety could cope resiliently with the climate of the future.

Pinot noir, with its dark skin and more sensitive nature, struggled under extreme conditions. Once a certain level of stress was reached, important chemical markers in the variety’s juice began to disappear. The plants reached a physiological breaking point.

Climate models predict that heatwaves will become increasingly frequent in many traditional wine regions, prompting researchers to investigate which grape varieties will survive in a changing world.