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Climate change has sobering effect on wine regions worldwide, but with uneven impacts

All of the world's wine-growing regions have been impacted by climate change, but with unequal impacts that vary across the growing season, reports a new study by E.M. Wolkovich of the University of British Columbia and colleagues, published in the journal PLOS Climate.

Winegrapes are an important perennial crop that has been highly affected by climate change. Studies show that warmer temperatures are shifting the regions suitable for wine growing toward the poles, while traditional regions are yielding grapes that ripen faster and have higher sugar levels, which alters the taste of the wine. But despite a growing body of research in this area, no one has taken a comprehensive global view of impacts comparing how climate change is affecting wine-growing regions worldwide.

In the new study, researchers studied the phenology of wine grapes—the timing of different stages of growth and reproduction of grapevines in response to the environment. They used data from more than 500 varieties, looking at 10 measures of climate, from the lowest temperatures during dormancy and when buds emerge, to heat extremes during the growing season, to temperatures and rainfall during harvest.

They found that climate change has impacted all wine-growing regions differently, which makes it difficult for growers to share strategies for adaptation. Europe has experienced the greatest shift, with significant increases in the number of hot days over 95°F and the highest temperatures during the growing season. In contrast, North America showed smaller increases in average temperatures and extremes.

The researchers conclude that global studies such as this one can complement regional studies and help growers adapt by providing insights into which regions are changing the fastest in response to warming and which are growing grapes in the most extreme conditions. If the global wine-growing industry hopes to navigate the impacts of climate change, they will need to contend with these complex changes, which vary between regions and throughout the growing season.

Dr. Wolkovich summarizes, "This study was a major interdisciplinary and international undertaking, requiring expertise from climatologists, crop modelers, macroecologists, and wine grape genetics experts from France, Spain, the US and Canada. It also relied on extensive data resources, and would not have been possible without the records of the INRAE experimental unit Domaine de Vassal, which has collected data on winegrapes for decades.

"I was very surprised by the level of warming across the globe, but especially in Europe, where our results show clearly just how much the growing season has warmed with human-caused climate change. As someone who has visited Europe for over 15 years, I have witnessed the increasing heat waves, but seeing the data—and how much change growers are facing—was sobering and even higher than I expected.

"The fact that the biggest shifts were in heat extremes and metrics related to total heat was also surprising, as we tend to expect climate change to warm minimum temperatures more—so I expected metrics like cold temperatures around the time of budburst and harvest to change the most—but it was often the metrics related to higher temperatures."