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High Alcohol Wines and Climate Change

High Alcohol Wines and Climate Change

There have been a number of reports about the increasing levels of alcohol in wines attributed to the effects of climate change. Hotter summers have played a key role in wine alcohol levels rising from 12.0 – 12.5% in the 1980’s to 13.5 – 14.5% today. However, there’s a second factor working here, and that’s the wine rating system according to Robert Parker, revised in the 1980’s, that rewards wines made with extremely “ripe” grapes.

An example of the effects of this winemaking philosophy has seen Pinot Noir wines move from lighter, fruitier wines with alcohol levels of 13%, to jammier wines with alcohol levels closer to 15%. Are these higher alcohol wines really true to variety?

A (partial) reversal in winemaking philosophy is occurring. Numerous scientific papers have been written on reducing alcohol levels in wine by physical and non-microbiological ways. An entire conference was convened to address this topic.

But wait, I want to ask a question. Is this the best way to address the conundrum of high alcohol wines? Consider that vineyard summertime temperatures have risen since the 1980’s. In fact, a 2004 article in Science magazine showed that the summer of 2003 was the warmest on record in France. The second hottest summer in France, however, was in 1760. Before 1760, and since, there have been hot years and cool years, and the quality of the wine produced was dependent partly on the temperature, but largely on how the winegrape grower responded to that year’s temperature.

Science European Avg Temp 1600 - 2003

Managing Winemaking with Climate Variations

But, regardless of what the climate is doing, a winemaker should decide on the type of wine he is interested in making, whether it is fruity, bold, high alcohol, low alcohol, etc. Then manage the vineyard accordingly:

1. Select the best grape and best clone of that grape for the vineyard. Remember, in Bordeaux in the 1970’s studies were undertaken to identify better clones for the cooler climate then being experienced. With unaltered viticulture practices, as temperatures increase a given clone will produce sugars faster than tannins will ripen, often leading to an imbalance with regard to “optimum ripeness”. Also, I don’t how many vineyards switched to cooler climate clones, but as summers warmed early in the 21st century some Bordeaux vintages were ranked with the best ever.

2. Manage the vines! Summer to summer temperature variations have always been greater than decade to decade, and longer, trends. Some varieties keep tannins and sugars in better balance with a heavier canopy, and some do it with a lighter canopy. And while it can be hard to do in some grape growing areas, increasing irrigation levels can also slow down sugar development relative to tannin development, keeping the vines in better balance.

What do you think? (References can be provided upon request.)

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