The best available measure of sustainability is the ecological footprint. After all, there's only so much planet to go around. And, the first thing we learn when calculating our footprint is how many planets it would take if everyone lived as we do.
So, if sustainability is defined as "one planet living", then we can use the footprint method to determine how much we need to cutback in order to achieve it.
Americans who haven't looked into this, be forewarned. Our footprint is flat out ugly! Would you believe 4 to 6 planets, depending on your income and household members? (Some footprint calculators may vary.)
The best tool I've found for looking into our footprint is called "CoolClimate" calculator from the Berkeley Institute for the Environment. It'll let you drill down to details for someone with your expenditure patterns and household choices.
Then, it will show you how how your footprint compares with similar households, with the American average, and with the world average.
I've used this tool to derive the priority ranking for elements of the typical American footpring as follows:
* Energy: 30%
* Transport: 25%
* Food: 20%
* Buildings: 15%
* Goods/Services: 10%
Putting our footprint in rank order helps us focus on where the biggest cuts need to be made.
This certainly puts the whole "green consumer" thing in perspective: all the organic cotton in the world doesn't come close to the carbon we're spewing to keep the car running and the lights on.
Oh, and, when you're looking at how you stack up versus the global average, bear in mind that we're already in overshoot. In round numbers, we're using up 1.25 planets at the moment. So, even if you get your footprint down to the global average, you've still got more reducing to do.
Try this tool to see how you might get close to "one planet" living. It's like way hard, I'll tell you. Even for me, living/working in a 500sf treehouse and using my ebike for local transport, it's hard to get below 3 planets. Yikes!
Of course, if my electric utility ever gets to 100% renewable sources and I join a "community supported ag" group, I could at least get down under 2 planets.
...Then I would have to really get serious. And this is what sustainability requires.