Published October 11, 2023
7 min read
Wine experts have warned for years that climate change could result in shifting harvest seasons, lower quality wine, and restricted plant growth. Yet here’s something to toast to: In Bordeaux, France, one of the world’s premier wine-growing regions, climate change may actually make wine taste better—for now.
A 70-year dataset of wine critic scores in Bordeaux, alongside high-resolution weather data from the period, revealed wine quality—based on factors such as rich and strong taste—increased over time, according to a study published today in iScience.
For the years 1950 to 2020, scientists analyzed the variation in overall Bordeaux wine quality and in 19 controlled designations of origin, or appellations d’origine contrôlée. An AOC, as it’s called, is a French geographical region with unique production methods and wine characteristics. The team’s statistical models tested how each AOC’s wine quality was related to weather factors such as season length, temperature, and precipitation.
The highest-quality Bordeaux wines came from years with warmer, drier summers; cooler, wetter winters; and earlier, shorter growing seasons, some conditions that climate change is expected to make more frequent in the region. For instance, warmer temperatures are predicted across France, with four degrees Celsius of warming projected by 2100. Warm temperatures can increase grapes’ sugar content and create sweeter wine.
Because Bordeaux wine producers traditionally rely on rainfall for water, rather than irrigation, there is a direct connection between the climate and wine productivity.
Study leader Andrew Wood, a climate scientist at Oxford University, was surprised to find increased rainfall during the non-growing winter season, when grapevines lie dormant, resulted in better quality wine for the following harvest.
“Traditionally weather during the growing season is considered for how it can affect grape quality, but the vines are there all year-round, and we found weather conditions in the non-growing season have an impact through the next harvest,” says Wood. More rain in the winter might result in better water balance in the soil during the growing season.
“Healthy vines make better grapes,” says Wood.
Bittersweet future
The improvement in quality could also be related to advances in winemaking technology or changing critics’ preferences, the study authors noted.
But one of the reasons Wood and colleagues chose Bordeaux is because its wineries largely rely on traditional methods, such as harvesting grapes by hand. This limits the influence of changing technology on the data.
And while wine critic scores are subjective, there was a consensus in their opinions. Wood and colleagues collected wine scores from public sources, such as online vintage charts, and 14 wine publications including Wine Spectator, Cellar Insider, and Hachette Wine Guide.
“We expected the critics to say different things because they’re catering to different markets, with different preferences, but generally, they tend to agree with each other,” says Wood. “People tend to like stronger, sweeter, richer wines. Even if people can’t necessarily pick out all the tasting notes, they can generally agree on what’s good and what’s bad.”
What’s more, the team’s statistical model suggests Bordeaux’s wine could continue to improve in taste as climate change creates warmer conditions, with less rainfall in the summer and more in the winter.
However, increased warming throughout the region and extreme weather events also put Bordeaux grapes at risk.
“The challenges are still very much there,” says Wood. “France is being hit with wildfires, which affects other Mediterranean wine regions like California and Australia, and smoke is really bad for wine. You can actually taste the smoke in grapes.”
Extreme heat also leads to drought. If climate change limits water and grapevines are unable to be hydrated, wine production falls apart.
“When we say less water in the summer is better, that doesn’t mean no water. There needs to be water in the ground that the plants can draw on, otherwise they’ll die,” says Wood. “So quality could increase up to a threshold, but we can’t say where the threshold is. It’ll get better, and then it’ll drop. And that’s the scary part, not knowing where the drop is.”
Climate change is already shifting harvest dates of French wine earlier in the year, which affects wine’s alcohol content and flavor. Recent hotter summers have also caused some grapes to wither or burn on the vine. Traditional regions for wine growing are also expected to move northward.
Limits to adaptation
Kimberly Nicholas, associate professor of sustainability science at Sweden’s Lund University, calls these changes in wine “climate change that you can taste.”
“Wine is a really climate sensitive crop. And unlike a lot of other crops, wine is about quality and not quantity,” says Nicholas, who wasn’t involved in the research.
The wine industry has been adapting to climate change in four key ways, she says: changes to winemaking methods, such as adding acids to adjust pH; altering farming practices by applying more irrigation or shade; planting vines in rows that are not located in direct sunlight; and replanting vineyards in new locations.
“The important thing to understand, though, is that there are limits to adaptation,” says Nicholas. “The wine industry is recognizing there’s a lot of room to maneuver, but that potential is not infinite.”
