O'Brien Productions/Corbis
DCL
Let me start by saying that I'm not advocating annoying people for the cause of green—but sometimes minor irritation can lead to big change. Allow me to explain.
Just about every major supermarket or store you shop in, every hotel you stay at—many, many places that provide you with services and goods also provide you with an opportunity to leave your opinion anonymously, thanks to the advent of the magnificent concept of the suggestion box.
Sometimes it's not always a box per se, it's often a courtesy form you can fill out and leave at the shop, hotel, whatever. I say, take these opportunities to pull for some green change.
You don't even to have any specifics in mind when you're jotting down your opinions, mind you, you can just note that you'd like to see the company adopt green values and initiatives. Just writing something like, "I've enjoyed shopping at your store, but I was wondering if you could supply more organic food options." Or simply, "I'd like to see more local food offered." Or perhaps the hotel you stayed at could be greener: ?I had a nice stay at your hotel, but I'd be more inclined to stay again if the company adopted some environmentally friendly policies."
This may seem like irksome meddling to some, but if the environment is really on your mind, why not let it be known? It's true that many people would be more inclined to shop at eco-friendly stores, so why not pass on the advice. And again, you can often do this anonymously—think of it as a quiet green encouragement. The more environmental issues enter companies' consciousnesses, the more likely we are to see change for the greener.

