Our cups runneth over this time of year. So do our recycling bins. The piles of empty bottles raise the issue of whether there's a greener way to package and ship wine. Turns out that the wine industry has been slowly but steadily moving away from the heavy green bottles that have been its mainstay for longer than anyone can say. The move toward tetra paks, bag-in-a-box contraptions (which are exactly what they sound like) and even plastic bottles is spurred partly by a desire to stand out on a crowded store shelf, appeal to a new market segment or to keep quality consistent. But there is also a definite eco-advantage to these new containers -- the wine industry is increasingly global and glass is heavy and not environmentally efficient to ship. British sommelier Garry Clark points out in his blog that the average case of wine weighs 18 kilograms, and nearly half that weight is the bottles. The eco-bloggers at TriplePundit turned me on to a great new study from the American Association of Wine Economists that looks at the carbon footprint created by shipping bottles of wine around the world and across the U.S. One-third of the red, white and bubbly Americans drink comes from overseas, primarily from Australia, and that portion is expected to increase as foreign purveyors push more aggressively into our growing market. Among domestic wines, 90% are made in California -- no surprise there. The study shows that that wine's carbon footprint is influenced both by how it's shipped and the distance it travels. Surprisingly, domestic wine isn't always the greener option. Moving wine in unrefrigerated container ships creates the fewest greenhouse gases. Refrigerated containers generate a few more. Shipping by air cargo, as small wineries might for their Web customers and club members, is the most fuel consumptive, creating 11 times as many greenhouse gases as the ships. Trains and trucks aren't nearly as emissions-intensive but still generate several times more greenhouse gases than ships. The study's authors say that because of distance, Australian wines have already created a sizable footprint by the time they're unloaded from their cargo ships in Los Angeles. Once they move inland, the level of carbon dioxide emissions involved becomes downright discouraging. For East Coast dwellers and Midwesterners, Aussie wines are quite an indulgence, environmentally speaking. Even on the West Coast it's hard to justify the greenhouse gases, given the great wines being made all along the Pacific Coast. But Europe isn't nearly as far as Australia, and delivering wine to the East Coast can happen primarily by ship. That changes things for some of us. The study says a wine from Bordeaux is a greener option than one trucked from Napa Valley for most people east of the Appalachians and in the Southeastern U.S. For folks further West, eco-conscious wine drinkers can stick to their American zinfandels, merlots and chardonnays.