Obviously it is possible to identify products which are not green. Like gasoline from tar sands, coal, or rayon. And some products are greener than others. For instance most analyses would find electricity from wind to be greener than bioethanol. But maybe we are approaching the point when it makes more sense to single out the products that are "not green" rather than those which are green, which will over time become the vast majority.
When "green" becomes main stream, maybe it only makes sense to single out products that are "even greener". At one time compact fluorescent light bulbs were considered "green", in spite of their heavy metal content. But today how can they be considered green when LED bulbs are much more energy efficient and have no mercury? CFLs went from green to gray.
This is a good argument for a green rating or score. The problem with such ratings is that they must be able to compare apples and oranges. (It is easy to compare apples and oranges of course, but here I am using the figure of speech in which the fruits play a metaphorical role. But you knew that, didn't you?) Which is greener, a Prius, an organic apple, a second-hand dress, permeable paving on a parking lot, or a solar hot water heater?
"Green" has many dimensions. Something can be considered "greener" if it
- Emits less greenhouse gases when it is being manufactured, transported, used, or disposed of than other similar products
- Causes the release of less toxic or environmentally harmful chemicals in its manufacture, transportation, use, or disposal
- Causes less ecological damage or negative land use changes in its production or disposal
- Causes less negative changes in biodiversity in its production, use, or disposal
- Uses less water in its production, use, or disposal
- There must be other dimensions. Tell me about them in the comments.
- Of course if we are considering "sustainability" more broadly then questions of effects on people, their rights, and equity must be considered.
In any event, we are rapidly arriving (at least in developed countries) at the point where "green" is the rule, rather than the exception.