We've all heard about sustainability, right? It's the buzzword that everyone from politicians to marketing gurus toss around, usually using it to imply some sort of careful, forward-thinking approach. Whether it's in government or manufacturing, sustainability-the ability to carry on for the foreseeable and unforeseeable future-is the holy grail of positive public perception. In other words, it's a good thing.

But it has a double meaning: either to sustain things the way they are, or to change things enough that the earth will be able to sustain those of us who are-and will be-living on it. The interpretation depends, I think, on who you ask. I'd say the key is to find the balance between treading lightly on the earth, and still carrying on the day-to-day activities most of us are expected to do.

Fortunately for us, there are growing ranks of green-minded inventors out there, creating new ways for us to live in a more eco-friendly manner. Thank them for big, exciting things like solar panels and Smart cars, and for many smaller things, too, from recycled-pop-bottle polar fleece to battery-free radios.

Do we need any of these products? Not necessarily. We could just go on as we are, driving our old gas-powered cars, using dangerous chemicals on our lawns and not worrying too much about it. Remember, sustainability could mean keeping things just the same. But there's also a growing understanding that keeping things the same simply isn't sustainable.

Consider this: an estimated 50,000 species are going extinct each year, largely victims of human development and industry. Or this: an estimated one in two people will develop cancer in their lifetimes-likely caused, as many now believe, by environmental pollutants. Those grim statistics are the result of sustaining an economy of perpetual growth.

Certainly, not everyone can buy an electric vehicle, or install solar panels, or start an organic garden in the name of a more environmentally responsible lifestyle. But we can all make choices that affect how clean and green our planet will stay for ourselves, and the future. M