Dear Umbra,

We are having a wedding in Kauai in September and are expecting about 40 guests. I would like to make it as “carbon-neutral” as possible. We’ve already instituted some greening aspects — recycled invitations, recycling at the reception, etc. — but would like to take it a step further. Obviously, air travel is the most significant contributor. Are there any organizations offering carbon offsets for weddings? I researched Future Forests, but was wondering if there are others out there.

San Diego, Calif.

Dearest Sean,

What a lovely, seasonally apropos question. Ye wedders and civil uniters force your guests to travel, and hence emit. Happy for you, less so for the earth.

Love is patient, and kind … and

Having a wedding to which every single guest must fly is a bit unusual, but at least yours is a small guest list. So let’s see what advice I can give. We’re going far beyond recycling, Sean, because you asked.

First, let’s tackle air travel. The Rocky Mountain Institute estimates that each domestic, commercial passenger-mile flown produces 0.65 pounds of carbon-dioxide emissions. Just to make a tidy word problem, we’ll say all 40 people are coming from San Diego, like you. That’s 2,600 miles to Honolulu, plus another 100 or so to Kauai. So to account for your guests’ round-trip journey, you need to cancel out about 140,000 lbs of CO2. (For a more detailed estimate, and fun with colorful graphics, check out Flying Off to a Warmer Climate.)

I know of no wedding-specific offsetter (entrepreneurs, take note!), but there are others you should look into. You’ve already discovered Future Forests, the U.K.-based tree-planters/climate-savers. Now take a look at the bounty of U.S. vendors selling green tags. These tradable renewable-energy credits offset your emissions — and your guilt — by investing your dollars in wind, solar, biomass, and the like. (Just as when you were shopping for formal wear, the costs will vary, from bargain basement to haute couture.) Of course, you could also openly pledge never to fly again as part of your vows. I hear violins.

As for the rest of your wedding, arrange a well-planned village. Consider a shuttle to and from the airport, so that no guest needs to rent a car. Try to lodge all comers in one location, and either do the ring thing nearby, or again with the shuttle. It also would sure be nice if said lodging were climate-friendly itself, and within easy walking or bicycling distance of Kauai’s other attractions.

All food served at the wedding would ideally be vegetarian, local, and organic, in order of importance. And to top off Umbra’s Extreme Eco-Wedding: no gifts. Instead, ask your guests to purchase green tags or donate to a climate-action group of your choice. Be sure to let them know they are attending a low-carbon wedding, and later spread the word on your blog. You know, your blog: