The conscientiously footnoted, 25 page paper bears the title Too much of a good thing? Causes and consequences of increases in sugar content of California wine grapes. In it, the authors apply themselves to the strange case of rising alcohol levels in California wines over the last couple of decades. Was the deed done by Mother Nature, in the vineyard, with her little heat index? Or was it done by Mr. Winemaker in collusion with Mr. Vineyard Manager, in the chais, by means of a doubled-barreled roto-fermenter?
The article is replete with heavy-duty mathematical formulas and sentences such as: In models with lagged dependent variables we could not compute Newey-West measures and so we report the OLS robust standard errors (Thanks for the heads-up, guys). However, the core argument isn't hard to follow.
The table below tracks a more or less steady increase in sugar content (measured in degrees Brix) at harvest for California wine grapes over a recent 20 year period (N.B. grapes with higher sugar content when fermented to dryness result in higher alcohol wine).
The data shows that the sugar content of all California wine grapes at harvest increased from 21.4 degrees Brix in 1990 to 23.3 degrees Brix in in 2008 - an increase of 7% over 18 years and 9% over the last 28. Since sugar converts directly to alcohol, a 9% increase in the former corresponds to a roughly equal increase in the latter.
Now have a look at the weather during the same period.
The weighted average heat index for places in California where significant amounts of wine grapes are grown during the period 1990 to 2008, does not show a substantial rise in temperature during a period that corresponds to the rise in degrees Brix.
Ergo, responsibility for rising alcohols in California wines can't be laid at the door of Mother Nature - even Mother Nature acting at the behest of big-time carbon emitters.
No, the data strongly suggests that heightened levels of alcohol are the outcome of deliberate decisions made by winemakers in the vineyard and the cellar in an attempt to give the public what they think it wants: bigger, richer, fatter, riper, more powerful wines.
Arriving at such a clear conclusion no doubt cheered the authors, but it hardly addresses the more compelling question: namely, why would wine drinkers have a preference for wines whose alcohol levels (and general scale) push the classical proportions to the breaking point?
My own sense of this is that justification for higher and higher prices has to be pegged to something, and that elegance, finesse, and poise are very much harder things to quantify and valorize than ripeness, density, weight, and sheer richness of material - all of which can come only from super-ripe grapes harvested at historically high Brix levels.
In this scenario, high alcohols become a marker for quality (and bragging rights) in the same way that horsepower once served as an unrivalled benchmark for quality in American automobiles, megapixels for digital cameras, and thread count for bed linen.
The problem with this is readily apparent. Each is a culturally approved and historicized marker of quality, not quality itself. We've long left behind us the idea that more horsepower in cars is invariably a better thing - and anyone who has shopped for a digital camera recently knows that megapixel counts above 10 or 12 are now essentially irrelevant.
Experts in bed linen will tell you it has always been a matter of the quality of the cotton, not the thread count of the sheet that matters. But so long as most of us remain ignorant of how to judge fineness in a fabric, we'll continue to count threads.
Somehow consumers have caught on to the idea that it makes no sense to apply our technical skills to making 500 hp automobiles. Why then does it make sense to deviate so dramatically from what wine cultures have for centuries recognized as appropriate proportions and build the wine equivalent of muscle cars - just because we can?
Stephen Meuse can be reached at firstname.lastname@example.org