I’ve been seeing more and more wines labeled “natural,” “organic” and “biodynamic.” And just when I finally learned the difference between pinot noir and petite sirah! Are any of these wines demonstrably better for the environment?

The Lantern sympathizes with your plight. Reading a wine label is about as easy as deciphering a Mayan hieroglyph. Unfortunately, there’s no simple solution for oenophiles looking to minimize their eco-footprint. Many factors contribute to an individual bottle’s overall environmental impact, including growing practices, packaging size and type, and shipping distance and method.

First, a basic overview of the terms. There’s a difference between organic wine and wine grown with organic grapes. Wines carrying the “made with organic grapes” label constitute the majority of certified wines in the United States. It means the viticulturalist — the person who grew the grapes — used no synthetic fertilizers, pesticides, herbicides or fungicides.

But the winemaker may have added sulfites, which kill off unwanted wild yeast and bacteria, and chemical clarifiers. Wine that is labeled simply “organic” is made with organic grapes and has no added chemicals.

Winemakers can also obtain “biodynamic” certification through Demeter, a nonprofit that has trademarked the term. Biodynamic wines must satisfy the same requirements as wines made with organic grapes. Unlike the “organic” label, however, biodynamic certification is not backed by the federal government. Demeter also imposes a variety of other standards. Biodynamic winemakers must use natural pest controls, such as ladybugs, and must supply a certain amount of their fertilizer from within the farm itself. The idea is to make the vineyard a biologically active, self-sustaining operation. Biodynamic wines may contain sulfites, but not synthetic clarifiers.

“Natural” wines have earned a certain cachet in the wine world. They’re supposed to involve as little human intervention as possible. However, because the term is completely unregulated, it’s very difficult to determine what role synthetic fertilizers, pesticides or winemaking chemicals played in the growing, fermenting or bottling processes.

With all other factors held equal, wine that is organic, made with organic grapes or biodynamic is better for the environment than its industrial shelf-mate. But the impact difference is smaller and more variable than you might think — and somewhat difficult to measure.

Organic winemaking practices have only a small impact on greenhouse-gas emissions, according to a 2009 paper in the Journal of Wine Research, in large part because even organic growers need some kind of fertilizer. Instead of synthetics, they use composted manure or plant matter, and a lot of it. Researchers at University of California at Davis compared organic and conventional chardonnay grapes planted in Sonoma Valley. They found that the organic vines required about 80 times as much fertilizer, by weight, as their conventionally grown counterparts. That material has to be shipped in from beef and dairy operations or nearby farms, which usually takes as much as or more energy than manufacturing and delivering the synthetic stuff.

There’s more to organic farming than minimizing greenhouse-gas emissions, though. And organic techniques do offer some substantial environmental benefits; they’re just tough to quantify. The Michael Pollan fans out there know that an organic vineyard supports a thriving ecosystem of birds, bugs and other critters, while a conventional field has been cleared of anything but the precious grapes. Conventional wine-growing can also expose local waterways — as well as farm workers — to fungicides, fertilizers and pesticides.

The most reliable way to minimize wine-related emissions is to avoid bottles that have traveled by air. If possible, choose bottles that spent more time in a boat than in a truck. Since container ships handle most intercontinental wine transport, Americans who live east of Nebraska are better off buying a wine from Bordeaux than one from Sonoma: The California wines would have taken a very long overland journey. Magnums are better than standard-size 750-milliliter bottles, because there’s less packaging mass per mouthful of wine. For the same reason, ask your local wine shope for producers that ship their wines across the ocean in bulk stainless-steel containers and then do their bottling close to the point of consumption.

The good news is that many of the world’s wine grapes are produced organically, even if the bottle doesn’t say so. Traditional vineyards in Burgundy, Piedmont, Mosel and elsewhere often stay in the same family for generations. Many of these vintners have stuck to organic farming practices but don’t bother with the expense and bureaucracy of certification.

Marketing also plays a role. Consumers often assume that organic dairy and produce are superior to the conventional stuff and willingly pay a premium for them. Wine snobs, on the other hand, tend to perceive organic wine as substandard because pioneering organic vintners had trouble overcoming the challenges of shipping and storing wines without added sulfites. (Advocates for organics insist these problems have been solved.) Even if they would qualify, many high-end producers don’t seek organic certification for fear that wine snobs will sneer. So ask your local wine merchant about any particular bottle. It may be covertly organic.

And prepare to do a spit-take, wine snobs. Oenophiles should care deeply about the environment, as the American wine grape could someday be an endangered species. While regions such as Mosel and the Loire stand to gain from a little global warming, one researcher estimates that climate change could wipe out 81 percent of premium wine production area in the United States by century’s end.

The Green Lantern, which is produced by the Web magazine Slate and can be read at www.slate.com , thanks Jim Fullmer of Demeter USA, Pablo Paster of TreeHugger.com and HARA, and Jonathan Russo of Organic Wine Journal for their help on this column.