I got a chance to read Tyler Colman and Pablo Päaster’s white paper, “Red, White, and ‘Green’: The Cost of Carbon in the Global Wine Trade,” which is summarized in Colman’s post.
The authors perform a detailed analysis of the carbon footprint (in terms of greenhouse gas emissions) of the production and distribution of a bottle of wine for consumption in the United States. The independent variable in their computations is the location where the wine is produced—Australia, France, Argentina, or California. Although they also analyze the effects of different agricultural practices (organic farming as might be typical in the various regions) and other links in the chain (such as CO2 released by fermentation), it turns out that the predominant carbon contributor is the means of shipping the finished, bottled wine and the distance that it must be shipped. For instance, for delivery to Chicago, a hypothetical 750ml bottle of wine from the Napa Valley produces almost 4.5kg of carbon dioxide; 3kg is accounted for by truck shipment from California. By contrast, wine from France, which is shipped by relatively efficient container ship, produces 2.0kg; and even here, shipping accounts for more than half of the total. The other significant components include the production of bottles, land use, and consumption of oak for in-barrel aging.
The results enable the researchers to draw a “green line” across the Midwest and South: to the east of this line, it’s more emissions-efficient to consume wine shipped from France than trucked from California (or Washington, presumably). Of course, if you’re fortunate enough to live in a state that produces its own drinkable wine (like I do, in Virginia), an even better choice would be the local tipple. Buying by the 1.5l magnum also helps: as they say, “shipping wine is often really about shipping glass with some wine in it.”
Two other asides: First, a footnote gives the nod to the general sustainability of cork as a bottle closure. Second, the writers note that growing grapes requires a lot of water for what you harvest: 1.2 to 2.5 megaliters per hectare, or 550 kiloliters per ton of grapes. This is partly due to the fact that grapes don’t yield a lot of mass per hectare, compared to a crop like corn.