That is, on October 11 the baskets and trailers were brought out to start the campaign in one of the strategic sectors of the region. In 2019 the harvest began at the end of August. Popular wisdom had been questioned for some time. About thirty years approximately. Although winegrowers and wineries were aware of this evolution, few had accurately analyzed the details of climate change. What have been the symptoms in recent decades? Where are the data to certify it? Sara Valencia, a young engineer from the University of Navarra, has been responsible for finding the patterns and turning them into her final thesis. The conclusions? As she explained to Terraview, an advance in veraison of 25 days, as well as 15 days in the case of budbreak and flowering.
Picasso used to say that inspiration should catch you working. And something like that happened to Sara Valencia when her eureka moment came: she was working on a modeling study of phenological conditions. That is, determining the factors that influence budbreak, flowering and veraison in order to create predictive models. “My goal was to adapt existing models to the climatic conditions of Navarra,” he says.
Under the supervision of Professor Carlos Miranda, Valencia began digging through the archives of the Estación de Viticultura y Enología de Navarra (EVENA). His findings, however, were radically different from what he was looking for. What he found were, black on white, the effects of climate change on viticulture in the area since 1984. “In the end we wanted to include it in the work because it seemed to us something important and very shocking,” he says.
Climate change in concrete figures
Oddly enough, no one had sat down to examine EVENA’s rich documentary archive in terms of global warming and its impact on viticulture. But as soon as Valencia began to compile the data and give it a graphical form, the trend became clear. “Starting from the Huglin index to analyze climate variability, not only did I find very large variations from one year to the next, but I detected a clear trend.” Between 1984 and 2018, veraison of Tempranillo vines has been advancing by up to 25 days. The variation in flowering and budbreak data is less marked, but also offers a 15-day advance. “It’s one thing to know that the harvest has been brought forward, but seeing it on a graph that clearly impacts you much more”. And not only that, but, according to international classifications of climate types, the Navarra region would be moving to a different climate.
Variations according to the type of grape
One of the main concerns in the wine world is the extent to which it is possible to adapt to global warming. Sara Valencia’s study, although it is only one part of the complex equation of climate change, points to the possibility of using varieties that are less sensitive to its effects. Although her research does not include factors such as fruit acidity or sugar content, it does show different behaviors depending on the grape variety.
Specifically, five varieties were studied: tempranillo, garnacha, graciano, merlot and chardonnay. The data for the first two show a certain divergence. While tempranillo, which accounts for 20% of the total area planted in Spain, shows an advance of 25 days in veraison, garnacha shows an advance of 20 days. During flowering there is also a difference of five days in the same direction, while the budbreak date is the same in all the records. “In general, the most marked change occurs in the final phenological stages, specifically veraison. We are talking about practically a month’s difference,” Valencia points out. “We all know that climate change is real, but here we are seeing the real impact on viticulture. It is even possible that ripening will be impaired, as shorter winters prevent the grapevine’s cold needs from being met.”
A more exhaustive comparison of varieties would be necessary before reaching conclusions, but initial data indicate that these varieties respond differently to global warming, as noted in the recent study published in the Proceedings of the National Academy of Sciences (PNAS). Theoretically, this would open the door to vineyard selection carried out under climate change criteria. “I think there is a lot of room for further research along these lines,” he concludes. Probably, along with research such as that of VitiAdapt, which analyzed the behavior of 52 vine varieties, one of the ways to analyze this evolution in the coming years will be the development of predictive models based on big data and artificial intelligence.
The vineyard as a vocation
Sara Valencia’s grandfather was a winegrower and her family comes from towns with a strong winemaking tradition such as San Martín de Unx and Olite. “Since I was very young I had to go to the countryside and I have always liked the world of wine,” she explains. In the end, she gave shape to these affinities by studying agri-food and environmental engineering at the University of Navarra. He is currently pursuing a master’s degree to specialize in oenology and, especially, viticulture. “I’m more of a field person than a winery person, my thing is to research the vine,” he said.
Sources: Navarra Capital, EVENA, PNAS, VitiAdapt, Wine Mag