The Eco-Over-Under : Are we making the greenest choices, or gambling with the environment?

All environmentally-minded folks are on the lookout for ways to help slow global warming and employ the three R's in as many parts of their lives as possible. Unfortunately, in the environment as in life, things can be more complex than we originally think. Are choices like buying local or reusable products always the most ecological option? Where is the point where it's better for the environment to reuse an item like a plastic container versus a disposable one? Like in gambling, what is the eco "over-under"?

When my kids' school announced an eco-lunch campaign, I was expecting, and received, information about using reusable plastic containers instead of cling wrap and sandwich bags, and a thermos or plastic bottle instead of juice boxes. I accepted that these were good ideas for reducing waste and global warming. My wife, on the other hand, has a tendency to examine all aspects of a question. "Is it really more ecologically sound to pack a lunch this way?" She asked. "Of course" I replied. "How come?" she asked, and I had to tell her, as I so often do, "I don't know." On the surface, it just seems obvious that reusable is better for the planet than disposable. But why?

I read an article in the February 25th edition of The New Yorker called "Big Foot: The Complexities of Going Green ." In it journalist Michael Specter discusses the hotly contested terrain of measuring carbon emissions. First Specter suggests that all forms of carbon consumption in our lives, like food, transportation, clothes, housing, and so on, should be given equal importance. For example, the average North American feels good about recycling, but is she equally willing to forego air travel?

Specter looks at the "localvore" movement (also known as the "hundred mile diet," where participants choose to consume only locally-produced foods) and asserts that assuming this practice is automatically more energy efficient than shipped produce is simply naïve. Local product A, grown slowly down the street on nutritionally depleted soil, with low crop yields, picked by hand, can leave a larger carbon footprint than imported product B, grown quickly overseas on densely cultivated lots, with high yields, picked efficiently by machine, he argues.

Consuming locally is beneficial, he believes, but not with all crops and not under all circumstances. For example, one study found that due to the difference in carbon use between transportation by sea (barge) and land (truck), a New York wine drinker is "greener" by consuming imported French wine than California varieties.

So in the end how do we measure the environmental impact-the eco-over-under-of reusable products versus disposable ones? Ask Pablo , a blog about "making sustainability metrics fun," calculated that a coffee or tea drinker using a stainless steel mug will have to reuse it 327 times before it has less of an environmental impact than a disposable Styrofoam cup. For years I have used a reusable steel coffee mug, and have broken, lost and replaced it a few times. Of the four mugs I have gone through over the years, I might be close to breaking even, but the whole exercise has got me thinking about other so-called "green" solutions.

If you pack your lunch with reusable containers, how many uses will it take to equal the environmental impact of using cling wrap, snack and sandwich bags? The calculation would need to take into account the energy used in manufacture and shipping of the containers, the amount of water and energy used for cleaning the reusable containers, the land-use of its place in the landfill site (where both disposable and reusable plastic eventually end up), and the number of times each container is actually used.

The point at which reusable containers really become more environmentally friendly is an elusive figure, but it would be interesting to know if it was five, fifty, or five hundred uses. While the reduction of disposable packaging in landfills is a laudable end in itself, like so many things in life, there's more to the footprint than the brand of shoe. While it's never an environmental gamble to reuse an item you already possess, buying new semi-reusable products might be a bet not worth taking. I welcome new, skeptical research that calculates to eco-over for all of our necessities, with the hope of truly living the slogan, "Think locally, Act globally."

—Roger