In this post I will use the information from one specific vintage chart, to look at the variation over the past century for the vintages from the most prominent wine regions of France (see Which French wine region is right for you?).
The Cavus Vinifera web site markets a wine-cellar management tool (also available in English as Your Cellar). Along with lots of other information, the site contains vintage charts for several of the wine-producing regions of France, mostly from the year 1900 up to a couple of years ago (Les millésimes en France de 1899 a nos jours). This is very unusual, as most vintage charts cover a much shorter period of time. This circumstance thus provides the opportunity to compare these French regions over the past century, to investigate to what extent vintage variation is correlated among these areas.
Almost every vintage from 1900-2014 has been rated on a scale of 0-20. The regions and wines covered by the entire time-span include:
Bordeaux (red)
Bordeaux (white)
Bordeaux (sweet)
Burgundy (red)
Burgundy (white)
Rhône (North)
Rhône (South)
Loire (red)
Champagne
Beaujolais
Alsace
The data are incomplete for the Loire (sweet) and South-West regions, which I have thus left out of my analysis.
As I did in my previous post on the topic, I have used a network to visualize these data, with the network being used as a form of exploratory data analysis. I first used the manhattan distance to calculate the similarity of the different wines, based on the quality scores. This was followed by a neighbor-net analysis to display the between-region similarities as two phylogenetic networks.
The network for the 11 wines / regions is shown in the first graph. Each wine type is represented by a dot in the network. Wines that are closely connected in the network are similar to each other based on the variation in their vintage quality scores through time, and those that are further apart are progressively more different from each other.
Not unexpectedly, many of the different wines from the same general regions do form neighborhoods in the network. For example, the three wines types from Bordeaux (in south-western France) are together; as are the three wines from Burgundy and Beaujolais (along the Saône River in eastern France); and the two wines from the Rhône River (in the south-east). Thus, we may conclude that broad-scale regional conditions do, indeed, affect the different grape types in a similar fashion.
However, the network location of the other three wines is less easily explained. For example, the Loire reds (from western France) are associated with the Rhône wines; the Alsace wines (from north-eastern France) are loosely associated with the Bordeaux wines; and the Champagne region (in northern France) is somewhat isolated. If I had been asked to guess beforehand, I would have expected the Alsace, Champagne and Burgundy wines to have similar vintage variation, based on their geographical proximity. So, why does the network reveal something quite different? There is something worth looking into here.
The network for the 115 years is rather a simple graph, which mostly just shows the same pattern as a graph of the annual vintage quality-scores averaged across all of the regions. This does, in fact, mean that a vintage chart for the whole of France could be generally useful. So, I have shown the simple annual averages in this next graph, instead of showing the network.
The poorest French vintages include 1902, 1910, 1913, 1930, 1931, and 1968. The best French vintages include: 1929, 1945 and 1947, followed by 1928, 1949, 1989 and 1990, and then 1906, 1953, 1959, 1961 and 2005. The 1910 vintage stands out as particularly poor, with none of the regions scoring more than 10 out of 20 for their grape harvest, and both Burgundy wines scoring 0! This contrasts with the best years, where no region scored less than 16 out of 20. Some of the top years are still revered by connoisseurs, at least for some of the regions.
Note that the 1930s were generally not a good time for wine-making in France, and nor were the 1910s (although 1906 was an early-century exception). The 1940s and early 1950s, on the other hand, were generally good times for wine production. Moreover, there has not been a bad vintage since the end of the 1960s, or even a mediocre vintage since the early 1990s.
Indeed, this graph shows one of the clearest effects of climate change in France — the consistent elimination of low-quality wine in regions that have traditionally been considered marginal. Marginal growing conditions have always been considered desirable for high-quality wine-making, but this comes at the risk of poor vintages when the weather is particularly nasty. These days, climate change has created considerable variation in vintage harvest volume, but has reduced the variation in vintage quality. Consistently warm growing weather ensures high-quality grapes, but it comes at the expense of potentially reducing the quantity of the harvest — for example, by late spring frosts (see Frost – the new normal?), lack of rain (see Wine’s emerging water crisis), or even heavy rain.
Climate change is a particular type of weather change, associated with atmospheric warming — it thus increases the variability in some weather characteristics and reduces it in others.
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