The buzz from global warming – wine, alcohol and climate.


Let’s pop open a nice bottle of Chablis while we consider why some wines seem to have more of an alcoholic kick than others (more on that in a moment).  Chablis, a wine region in the northern part of Burgundy,  has a relatively cold climate, and its wines are made exclusively from the Chardonnay grape.  A Wine Concepts favorite producer is Domaine William Fèvre, and today we’re tasting their 2016 Chablis "Champs Royaux" (about $16 retail).  On the nose it has citrus, peach and a hint of honeysuckle, and on the palate it has a crisp acidity, green apple and nice minerality.  It pairs well with oysters, seafood and sushi.  (If you're looking for a buttery, oaked California Chardonnay, however, this is not the wine for you.)  For a special occasion, the Fèvre Chablis Premier Cru "Montée de Tonnerre" (about $60 retail), from the best of the Chablis Premier Cru climats, is a more concentrated and complex wine, and is the perfect pair for lobster and drawn butter.

Why did I pick this wine?  Chablis is often overlooked, and the Champs Royaux is a nice, good value wine.  That's reason enough, but the wine also helps to make a point about alcohol levels in wine.  Wines from colder climates, such as Chablis, tend to have lower alcohol (and higher acid) levels than similar wines from warmer regions.   And, white wines tend to be less alcoholic than red.  By way of comparison, the alcohol content for a typical warmer-climate California Chardonnay can run from 13.5  – 14.5 percent or more, compared to 12.5 percent for the Fèvre Chablis.  Some California red wines, such as Cabernet Sauvignons and Zinfandels, can have alcohol levels above 15 percent.  To put that in perspective, a California Chardonnay can have 15 -  20 percent more alcohol than a Chablis.  Needless to say, you’ll feel the effects of a lower alcohol wine less than a higher alcohol wine.

The key factor affecting a wine's alcohol level is the amount of sugar in the grapes, which increases as the grapes ripen.  After the grapes are crushed, yeasts convert sugar into alcohol.  The more sugar in the grapes, the higher potential alcohol level in the wine (to a point - yeasts die when the alcohol level reaches somewhere north of 15 percent).  In cool climates, the grapes sometimes do not ripen sufficiently and, where legally permitted, the winemaker may add some sugar.  That sugar does not sweeten the wine -- it is added prior to fermentation and converted into alcohol.

Over the last 20 years or so, the average alcohol level in wines has increased from 12.5 - 13.5 percent to 13.5 -14.5 percent.  In part this is a reaction to consumer preferences - many well-known wine critics tend to rate more alcoholic (therefore more full-bodied) wines highly.   If you want a wine with a lower alcohol level, here's some tips:

  • Generally, wine produced in a cool climate will have lower alcohol levels than wine produced in warmer climates. In cooler climates, such as northern France, Germany and northern Italy, the grapes struggle to ripen and therefore have lower sugar levels.  Some lower alcohol wine alternatives:
    • Reds: Pinot Noir from Burgundy; Valpolicella from Italy's Veneto region; and Beaujolais.  In contrast, the following wines have relatively high alcohol levels: California Cabernet and Zinfandel; Australian Syrah; and southern Rhône red blends.
    • Whites: Muscadet (from the lower Loire valley); Pinot Grigio from the Friuli-Venezia-Giulia region of northern Italy; Vinho Verde from northern Portugal; Assyrtiko from the Greek island of Santorini; and Chablis.
  • Higher quality wines typically will have a higher alcohol level than lower quality wines from the same appellation. That is because the grapes used in higher quality wines are more concentrated, and perhaps riper, than those in lower quality wines.  For example, legally a Chablis wine must have a minimum alcohol level of 10 percent, a Chablis Premier Cru 10.5 percent and a Chablis Grand Cru 11 percent.  Of course, the actual levels are typically higher.
  • Sweet wines have higher alcohol levels than dry wines.   Often, dessert wines have alcohol in the 15 - 20 percent range. For example, a Port may be 18 percent or more alcohol by volume. These wines are typically served in smaller quantities than a table wine.

Although wine labels must display the alcohol level, don't believe everything that you read. For U.S. wines that contain less than 14 percent alcohol by volume, the level stated on the label can vary by 1.5 percent from what’s actually in the bottle.  So, a wine labeled as 13.5 percent could contain up to 15 percent alcohol.  For wines above 14 percent, the allowed variance is 1 percent, so a wine labeled 14.5 percent could be as high as 15.5 percent.  My experience is that when the alcohol content varies from the label, it varies upward, not downward.  Speaking of a variance between what’s on the label and what’s in the bottle, generally a U.S. wine that shows a grape variety on the label need only contain 75 percent of the grape variety.  (Some states, such as Oregon, are more stringent.)  For example, the 2014 Silver Oak Napa Cabernet Sauvignon contains 78% Cabernet Sauvignon, 12 % Merlot, 6% Cabernet Franc, 2% Petit Verdot  and 2% Malbec.  That's not necessarily a bad thing, as you can tell from tasting the wine, but it is often misunderstood.

So, what does alcohol level have to do with global warming?  Rising temperatures have had some positive impacts on the wine industry.   Cooler regions that once struggled to ripen grapes are now seeing warmer temperatures, later harvests, riper grapes and therefore higher alcohol levels.  (In Burgundy, global warming is referred to as "Le Bon Problème".)  In fact, some areas that historically could not produce wine are now doing so - care for an English Pinot Noir?   Of course, there's more at play than just just rising temperatures.  Winemakers have developed better viticultural techniques that result in riper grapes even in cooler climates.

Finally, if you want to know more about the health effects of alcohol, click here.