“There are two big points in this paper, the first is that harvest dates are getting much earlier, and all the evidence points to it being linked to climate change,” study author Elizabeth Wolkovich of Harvard said in a statement. She and her team examined over 500 years of French harvest records to draw their conclusions. “Especially since 1980, when we see a major turning point for temperatures in the northern hemisphere, we see harvest dates across France getting earlier and earlier,” she said.
Because wine grapes rely so heavily on climate — and because meticulous records on wine harvests go back much further than most sources of climate data — the researchers hoped to use the fruit as a sort of canary in the coal mine, showing just how profoundly climate change might affect the planet’s crops. Average temperatures in France have risen about 1.8 degrees Fahrenheit since pre-industrial times, and they’re still rising.
Traditionally, it took a dry summer to get temperatures toasty enough for these prized early grapes. But these days harvests are happening an average of two weeks earlier than they did in the 400 years preceding 1980, and the relationship between rainfall and harvest time seems to be breaking down.
For now, that means several banner years in French wine production. But there’s an upper limit to this effect, and we’re going to reach it.
“Past a certain point, you are no longer getting a benefit from higher temperatures, and you may even see a deterioration in quality,” Benjamin Cook, the study’s lead author and a climate scientist from Columbia University’s Lamont-Doherty Earth Observatory and NASA’s Goddard Institute for Space Studies, told CNBC.
“The trend, in general, is that earlier harvests lead to higher-quality wine, but you can connect the dots here,” Wolkovich added in a statement. “We have several data points that tell us there is a threshold we will probably cross in the future where higher temperatures will not produce higher quality.”
This might mean that grapes have to shift around to new regions to find their ideal climate. In France, that could pose a big problem: Certain French wines, such as Champagne, have to follow rules about where and how their grapes are grown. The grapes that make these wines might find plenty of other places to flourish should their traditional regions shift into hostile temperature ranges, but that would mean changing the very notion of what it means for Champagne to be Champagne.
“For many wine-makers, changing these rules is tantamount to changing the identity of the wine,” Agence France-Presse reported.
And the truth is that climate change isn’t the only thing that will dictate wine quality in the years to come. It’s still a complex process with a lot of factors. And it’s likely that individual regions and grape varieties will handle the shift differently.
“Droughts are still likely to affect vine health and development and the wine industry independent of temperature effects, especially in wine-growing regions that are significantly drier than France,” the authors wrote in the study. “And our results do not necessarily presage an inevitable future where wine quality is dominated by environmental changes. In reality, grape harvest date and wine quality depend on a number of factors beyond climate — including wine grape varieties, soils, vineyard management, and winemaker practices.”
That doesn’t mean that winemakers shouldn’t be mindful of past and future climate shifts.
“We are looking at climate change that, on average, has warmed globally about 0.6 degrees Celsius,” Wolkovich said in a statement. “But as we go forward, with projections of two or more degrees of additional warming, we could be talking about significantly earlier harvests.”