What climate change might do to your favorite wine

Terroir and climate have both been topics of fierce debate. Just as some people don’t believe climate change is real, some oenophiles think terroir is a ruse, a mere marketing tool. Recent extreme weather events are certainly real: In this grape-growing season we have seen massive floods wash out vineyards in western Germany and severe drought affect California’s wine regions. Is it possible that certain places may no longer be viable for the grapes traditionally grown there? And how might wine regions and the characteristics that define their wines shift as a result? When I put these questions to wine professionals, climate scientists and a terroir consultant, I heard conflicting answers as well as a few reasons to hope amid much despair.

Today, winemakers, marketers and writers alike tend to invoke “terroir" with reverence, to describe a distinctive wine of a notable place, but it wasn’t always so. In his book “Terroir and Other Myths of Winegrowing," Mark A. Matthews notes, “[F]rom our earliest records, terroir is employed as a pejorative when describing wine flavor, and that undesirable flavor is described as the soil." Not until the French instituted the modern appellation d’origine contrôlée system for wines in the early 20th century, establishing the importance of a specific place and the unique conditions there to grape growing and winemaking, did the word acquire its current cachet.

When I talked to Chile-based terroir consultant Pedro Parra, who holds a Ph.D. in terroir, he defined terroir as a combination of nature and human intervention. Mr. Parra’s book “Terroir Footprints" describes his work with viticulturists and winemakers all over the world and his passion for soil (and especially rocks). He believes climate change can alter a wine region’s terroir.

Burgundy vigneron Véronique Boss-Drouhin, who oversees winemaking at her family’s Beaune-based domaine, does not believe climate extremes have affected Burgundy’s winemaking negatively. In an email she wrote, “Global warming has been a good thing for the quality of the wines." She cited increased temperatures as beneficial for a region where the weather in the 1970s and 1980s was often too cool or too rainy for grapes to ripen properly.

But even if quality remains high, extreme weather has certainly minimized the quantity of Burgundy wines. For example, three years in a row, 2012-2014, violent hailstorms damaged up to 40% of the harvest in the Côte de Beaune, while in 2016 many vines suffered from an intense frost in April. (While isolated hailstorms and late frosts occurred in the region historically, their consequences may be greater now. For example, the Bourgogne Wine Board found that the temperature in Burgundy has increased by one degree Celsius since 1987. This means earlier bud break and greater potential harm from spring frost.)

Ms. Boss-Drouhin’s family also makes wine in Oregon, at Domaine Drouhin Oregon. Mr. Parra believes this U.S. state will be a prime destination for winemakers seeking new places to plant. When the Drouhins established their domaine in the Willamette Valley in 1987, the region was cooler and rainier than it is today. As the region’s climate became sunnier and its weather and crops proved more reliable over time, other Burgundians established their own Oregon domaines. For instance, Jacques Lardière, formerly of Maison Louis Jadot, established Résonance with Thibault Gagey in 2013, and Jean-Nicolas Méo of the famed Burgundy Domaine Méo-Camuzet created Nicolas-Jay in Oregon with his friend Jay Boberg in 2012. Mr. Parra, who makes wine at his own winery, Pedro Parra y Familia, in Chile’s Itata Valley, sees the appeal. “If I had the resources I would buy in Oregon," he said. “It is becoming perfection in the balance of soil and weather."

Mr. Parra believes the changing climate could cause shifts both bad and good. “It brings opportunities for new regions and problems for old regions," he said. On the positive side, he cited the recent wave of Champagne houses that have invested in southern England, where temperatures have risen over the years, enabling grapes to ripen fully, and whose chalky soils are similar to those of Champagne. For a more troubling trend, one need look no further than the Napa Valley, repeatedly afflicted by fire and drought in recent years. Yet Napa’s misfortune might mean enhanced opportunities for winemakers in other parts of the world—Argentine Cabernet producers, for example, whose high-quality wines have for so long been eclipsed in the market by Napa’s fame.

How dire might the situation in Napa become? Could things worsen to such a degree the region would be completely inhospitable to growing grapes? I put the question to Elisabeth Forrestel, assistant professor of viticulture at University of California, Davis. Prof. Forrestel is leading a research program on the effect of climate change, specifically heat extremes, and Napa Cabernet is one of the wines her team is studying.

“There is no question that we can continue to make wine in Napa," said Prof. Forrestel, who works with California grape growers in gathering research, “but that’s not to say that practices won’t change." She cited the need to pick grapes earlier, change water application practices and perhaps plant other varieties. “I think that Cabernet will still be there, but there will be more grape diversity," she said.

Oregon-based climatologist Greg Jones noted that drought is the most serious issue facing winemakers in California today. He, too, emphasized the need for grape diversity when we spoke by phone: “We have 5,000 different varieties out there and to a large degree we grow only 25 of them." Mr. Jones suggested that a variety such as Xinomavro, a red grape native to Greece, would do better in drought circumstances like Napa’s than Cabernet Sauvignon does. Of course, replacing Cabernet with Xinomavro isn’t just a matter for winemakers to consider; marketers and wine buyers need to get on board, too. “We have to retrain customers," Mr. Jones said.

I don’t know if I’ll be around to see cult Xinomavros from Napa, but surely diversifying grape varieties, picking earlier and altering irrigation practices would alter the terroir of any wine region. In other words, human intervention may become an increasingly important factor in the expression of terroir. As Mr. Parra put it, “The interpretation of the winemaker is important. The winemaker is the doctor."