Glass bottles are not as environmentally friendly as alternative packaging options for wine, experts say.

Bad news: If you're trying to drink sustainably, glass bottles are not the best option.

In fact, when you stack glass bottles up against alternative packaging options — like aluminum cans and bag-in-box — the bottles lose on just about every count, according to Mark Falinski, head of research and sustainability at Finch, a new company that assigns products sustainability rankings.

The carbon footprint of glass bottles is about 5 times larger, and the water use about 4 times larger, than that of the bag-in-box, says Falinski. That remains true even when you consider the fact that the bag-in-box involves plastic. The plastic bag inside the cardboard box is still preferable to the glass bottle, he says, because it tends to funnel less material to the landfill. Only about 30% of glass bottles get recycled in the U.S., data from the Environmental Protection Agency shows.

The ecological virtues of aluminum, however, easily trump both glass and bag-in-box vessels. Basically, aluminum is awesome. It's easier to recycle: About 75% of all the aluminum ever made is still in circulation, Falinski says. Aluminum is also easier to transport — it's lighter and easier to stack — meaning that moving it around results in fewer trucks on the road, and therefore fewer greenhouse gas emissions. A liter's worth of aluminum wine cans, Falinski points out, weighs 30% less than a liter's worth of glass wine bottles.

This all has interesting implications for the ways in which wine drinking could evolve in the future. On one hand, it feels impossible to imagine a world in which the wine industry abandons glass bottles, which have been its package of choice for probably thousands of years.

On the other hand, there's way more openness to alternative wine packaging than ever before. Just five years ago, canned wine was a rogue curiosity, typically reserved for low-quality swill; by 2020, it represented a $210 million market, and Grand View Research expects it to grow 13.2% annually through 2028. They're no longer on the fringe — canned wines are now just a permanent part of our wine landscape.

Some canned wines are now even dipping into an audaciously high price segment. At the Oakville Grocery a few days ago, I spotted a new wine from Napa vintner Jean-Charles Boisset, called the Oakville Wine Merchant Cabernet Sauvignon, for $65 per 250ml can. That would translate to a $195 standard-size bottle.

It's not just cans anymore, either: I'm excited about the burgeoning movement of wine in aluminum bottles. I've written about Revelshine, a shiny line of California wines that proved ideal companions for a national-parks road trip I took last summer. A new company called CCL Container recently launched an aluminum wine bottle intended for broader use across the industry, and a Denver winery has already started using it. 

There's a financial barrier, since canning wine in aluminum vessels often costs more than bottling it in glass. Wineries have extensive infrastructure devoted to glass bottles, and it will be difficult to break free from that. For smaller-scale wineries, it may be harder to justify aluminum packaging, since some canning lines require the producer to commit to a large volume.

But even more surprising than the rise of cans has been the bag-in-box comeback. For a long time, boxed wine was a synonym for the cheapest, sweetest wines available, like Franzia and Bota Box. Slowly, that's changing, as boutique wineries like Sonoma County's Ryme Cellars put their wines into boxes. The latest entrant into this category is master sommelier Andy Myers, who released a product with the very on-the-nose name of Really Good Boxed Wine.

These shifts are small blips on the face of the global wine industry, which remains heavily weighted toward glass bottles. But the fact that alternative packaging methods have gained so much more acceptance in the last few years than in previous eras makes me believe that a more significant shift away from glass bottles is possible, maybe even likely, at some point in the future.

I'm not advocating for the wine industry to abandon glass bottles altogether. I love them for their sense of ceremony: the satisfying snap of the cork popping out of the neck, the comforting glug-glug sound of the liquid as it pours out. I love the feel of a glass bottle in my hands, the rich dark-green and dark-amber colors, the beauty of their curving shapes.

But I'm also here for the brave new world of boxes, cans and aluminum bottles that will, I expect, appear increasingly on my table in the years to come — and whatever newfangled vessels may come next.

Senior wine critic Esther Mobley joined The Chronicle in 2015 to cover California wine, beer and spirits. Previously she was an assistant editor at Wine Spectator magazine in New York, and has worked harvests at wineries in Napa Valley and Argentina.