Dilemma: If all three Pinots are equally appealing to me, should I opt for the one with the natural cork, synthetic cork or metal screw-top before I toast to Mother Nature?

Of course I'll: Choose natural cork. It's a renewable resource.

Trade-off: The corks aren't easily recyclable, and there are only so many wine-cork trivets a person can make with the leftovers.

Then I'll: Use the synthetic cork and leave the real stuff to grow on the trees.

Trade-off: They're made of plastic and, if recycled, get turned into downstream products, not reused.

Then I'll: Ignore screwy wine snobs and unscrew the metal top.

Trade-off: Like plastic corks, the recycled metal closures can be recycled. But where's the romance in a twist-off?

Experts say: There's a lot to like about natural cork, from an environmental point of view. "Cork is naturally renewable, and historically, cork growing is a low-impact process, which doesn't even require trees to be cut down," says Darby Hoover, senior resource specialist for the Natural Resources Defense Council. "Cork is harvested from trees in a way which keeps the tree alive to grow more cork, which is harvested again some years later." Indeed, the World Wildlife Fund points to cork production as a means "to preserve the precious and beautiful woodlands that have uniquely clustered in the western Mediterranean for millennia."

Hoover points out that natural corks are commercially compostable (as opposed to home composting), so you can throw that cork in the green bin.

But Jack Macy, commercial zero waste coordinator for the San Francisco Department of the Environment, points out that both natural and synthetic corks have problems. "Natural corks usually end up in landfills unless they are reused, made into something else by the consumer or collected in a special cork recycling collection such as ReCORK with Whole Foods stores," Macy says.

And it's hard for recycling systems to differentiate between plastic and natural cork. "Synthetic corks can theoretically be recycled but are hard to recover in the recycling stream at sorting facilities. Even if they are recycled, they would be downcycled into another product," like pencil erasers.

His preference is for metal: "They are relatively easy to recycle and can be made almost infinitely back into metal screw-tops."

Verdict: Putting aside worries about "cork taint," or the presence of 2,4,6-trichloroanisole (TCA) that sometimes afflicts wine closed with natural cork (and that may be too big a worry to put aside, for some readers), the natural cork is the most eco-friendly option. Just be sure to turn in old corks to a program like ReCORK ( www.recork.org) or throw them in the compost bin. Ease of recycling makes metal screw-tops a good alternative.

Of course, it's often impossible to tell which bottle has a synthetic cork and which has a natural one until you've opened it. Until labeling guidelines change, you'll just have to remember which wine got you in the most environmentally friendly mood.

Have a dilemma for the Green Scale? E-mail home@sfchronicle.com.