One subject that is guaranteed to raise the hackles of Wine Society members is the seemingly inexorable increase in alcohol levels in wines. Gone are the days of the 'luncheon claret' at 12% or 12.5%, with today's average for Bordeaux closer to 14%. Despite the fact that balance, which is the key to any good wine, can be maintained at this higher level by skilful winemakers, there is no doubt that people are increasingly watching their alcohol intake. When the Chief Medical Officer pronounces that 14 units of alcohol a week is the recommended maximum consumption for adults, one starts to look very closely at the alcohol level indicated on the labels of the bottles in the wine rack.
Warmer weather = higher alcohol
The higher levels of alcohol are due in large part to rising average temperatures globally. The warmer the weather the more readily grapes ripen, and therefore the higher the sugar content at harvest time. This translates into higher alcohol, as the sugar is converted during the fermentation process.
I wrote a piece earlier this year about the addition in 2019 of seven varieties to the list of permitted grapes in Bordeaux. The initiative, which applies solely to Bordeaux and Bordeaux Supérieur producers, is a reaction to the increasing effects of climate change on winemaking in the region, and the new varieties were approved in a bid to help mitigate some of the challenges brought on by global warming.
But replanting your vineyards with new varieties is a very radical, expensive and time-consuming step for a grower. So before taking the bold decision to pull up your merlot vines and replant with touriga nacional, many winemakers are looking at other solutions in their vineyards.
Pampered vines = balanced wines
According to François Despagne, the passionate viticulturalist and engaging owner of Château Grand Corbin Despagne in Saint-Emilion, the vineyards of Bordeaux have never been so pampered, tended each year to ensure the healthiest, ripest grapes at harvest. According to François, hard work in the vineyard can moderate the potentially damaging effects of Bordeaux's humid maritime climate, reducing the incidence of vine disease and also lowering yields to ensure high-quality grapes and well-balanced wines.
The technique of effeuillage, stripping leaves from one side, or sometimes both sides, of the rows of vines is one of the most widely employed practices. This increases evaporation around the grapes encouraging sugar concentration, and the effects are particularly pronounced in hot vintages. This manual (or occasionally mechanised) work is often done routinely by growers well before harvest in July or even June for the first side, before growers know how the mid-term weather forecast of the summer will be. A second leaf removal is sometimes carried out at the end of the summer – typically more moderate than the first. This practice is essential in damp vintages such as 2007 or 2013 in Bordeaux, as it allows the grapes to be aerated to avoid the onset of grey rot. But in hot, dry vintages it can contribute to escalating sugars, and therefore potential alcohol levels.
Bunch thinning or green harvesting
Another technique widely employed in recent years, particularly by the top châteaux, is that of the vendange verte (green harvest). This is the removal of as-yet unripe bunches from the vines to ensure that the remaining bunches ripen fully. This practice would have been inconceivable half a century ago as the châteaux needed to produce sizeable crops where possible. This is entirely understandable because the hit-rate for successful, decent-sized harvests was low. Often in the past yields were tiny, with vineyards damaged by mildew and/or rot; winemakers needed to compensate financially for a small crop one year with a large crop the next.
For example, the 1961 harvest, famous for its superb quality, was just 10% of a normal crop in terms of yields; 1962 was a large harvest; 1963 was very poor indeed, with some châteaux producing no wine at all. The same went for 1965 and 1968, and 1972, 1973, 1974, 1977, 1980, 1984, 1987 and 1992 were all poor vintages. So there was a haphazard aspect from one vintage to the next, with the impact of weather conditions very considerable.
Gradually, understanding of viticulture, improvements in techniques and the development of vine treatments have helped iron out the hit-and-miss nature of making wine in Bordeaux. But today's practice of green harvesting can in hot, sunny vintages lead to overly ripe bunches, and therefore the danger of producing highly alcoholic wines.
Growing grass between the rows of vines
A third vineyard practice that can affect alcohol levels in wine is the planting of grass between the rows of vines. The advantage of this practice is that when it rains, the water is taken up by the grass roots instead of the vine roots, so in rainy vintages this helps avoid dilution in the grapes. But the other side of the coin is that in hot, dry years the grass cover competes with the vines for moisture, effectively concentrating the sugars in the grapes, with the evident knock-on effect on alcohol levels.
Balance is key
As mentioned earlier, the notion of balance in a wine is crucial. There are three pillars to balance, sugar-alcohol, acidity-pH and tannins. If one is out of line with the others, there is an imbalance in the wine. This is one of the reasons why François Despagne turned to organic farming, giving up all use of synthetic chemicals which stimulate the vine. In particular, he does not use any synthetic anti-botrytis products as these modify and slow down phenolic maturity in the grapes. Many growers in Bordeaux today base the timing of their decision to harvest purely on phenolic maturity, no longer looking at sugar and acidity levels before making their call about when to pick, and this can lead to a loss of balance. The higher the alcohol, the more important it is for the acidity and pH to be at levels that maintain a sensation of freshness in the wine. Bordeaux 2019s, which we offered en primeur this summer, are a perfect example of a Bordeaux vintage in which balance and freshness have been maintained despite high alcohol levels.
According to François, thanks to organic farming he has in recent vintages been able to lower his pH levels significantly, reducing the need for sulphites for the conservation of his wines. A Bordeaux wine with more alcohol, yes, but without being a caricature.
To conclude, it is clear that much can be done in the vineyard to help mitigate the effects of climate change. Many winemakers are already, depending on vintage conditions, employing or reining back the techniques discussed above. What is most important is that Bordeaux doesn't lose its unique character. As François Despagne notes, 'Bordeaux must remain Bordeaux'.