According to the annual assessment by United Nations Environment Programme (UNEP), the world is on course for a 2.6-3.1°C rise in global temperatures over the course of this century if nationally determined contributions (NDCs) to cut CO2 emissions are not significantly enhanced.
Climate change is impacting rainfall patterns, shifting vegetation boundaries, and leading to heat spikes and sunburn. Much of this can be managed with infrastructure improvements and additional work in the vineyard. However, what will be unavoidable is a sustained increase in temperatures—an effect that will affect traditional grape varieties. A glance at the alcohol levels of some famous wines today already reveals the significant, often undesirable, changes underway.
Varieties with star potential
Yet there are positive examples. After decades of being vinified as a white wine and valued for its acidity in Cava, the Trepat grape is now maturing as a full-bodied red with moderate alcohol and pleasant freshness in the DO Conca de Barberà. Similarly, in white wines, the French Picpoul de Pinet has evolved significantly. “When I was conducting research in Montpellier in the early ’90s, it was a simple, light wine. Today’s best examples are of an entirely different caliber,” explains Hans R. Schultz, who moved from southern France to Geisenheim University in 1995, where he is now president.
However, Picpoul also illustrates a research dilemma. Regional specialties receive little attention. “International relevance plays a role in selecting research subjects. On top of that, studying grape constituents and their drought and heat resistance are two entirely separate fields,” says Schultz. While some researchers look for vines that can withstand changing rainfall patterns, others focus on how aroma develops under various conditions, often using entirely different grape varieties.” In this field, there are significantly more projects with red varieties, as the effects are easier to measure in color compounds and tannins. With white varieties, the relevant compound groups often need to be identified first, which is much more challenging,” explains Schultz. Only by combining both areas of study can we identify the ideal vines for the second half of the 21st century, though collaborative initiatives are currently lacking.
As head of the OIV’s climate group Schultz has a comprehensive view of global efforts in viticulture research. Montpellier's well-respected research institute also oversees the Domaine de Vassal, home to around 10,000 grape varieties and Vitis species. “The Domaine was nearly shut down due to high maintenance costs,” Schultz recalls, “but now its importance is widely recognized. Unfortunately, this awareness doesn’t come with a budget for systematic climate change research on these grape varieties.”
From Greece to France
Comprehensive research exists on about one hundred widely cultivated grape varieties. In 2008, Professor Cornelis van Leeuwen from the University of Bordeaux published a study on the heat requirements for bud break in key grape varieties. In the following years, Dr. Amber Parker expanded this knowledge with global data on ripening stages and sugar levels in grapes.
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