In the sidebar there is a link to "Calculate your ecological footprint." This is a quiz, designed several years ago in honor of Earth Day, which asks you a fairly small number of simple questions about your lifestyle and activities, then gives a rough estimate of the planetary resources you are using, calculated in acreage.
Obviously only a rough estimate is possible, but doing the estimate is nevertheless a valuable heads-up, especially for Americans and others accustomed to a high median standard of living. For instance, my calculated footprint, 11 acres, is less than half the average footprint for my countrymen and women (24 acres). Hooray for me!
"If everyone lived like you," the calculator tells me, "we would need 2.6 planets."
Your results are also broken down into several categories, and the numbers can be instructive. For instance, I often agonize mentally over the decision to walk or drive across town; saving energy this way is also a matter I discuss with my child. The calculation, however, suggests that transportation is the least of our worries. Only half an acre out of the 11 represents mobility costs, and that includes one plane trip per year and a long cross-country drive or two. Much more significant are my housing and food impacts. I live in a small apartment (2 residents), eat little meat compared to most Americans, and approximately half (I guessed) of my food supply is locally-produced (local farm vegetables, local dairy products, local eggs, locally-baked bread made with locally-grown wheat, local beef and buffalo... but then there is the prepared stuff, the coffee, the juice, the cereal, the wine, the chips... I'm trying to be realistic).
So. Good so far, but not good enough. And I should worry less about my car, and more about turning down the heat in the winter, switching to compact fluorescent lighting, buying cheese made here instead of in Minnesota.
If you do a calculation like this every once in a while, you can also see how the numbers change. I did this same quiz a year or two ago. My footprint is larger now. What changed?-- my housing, I think. Dividing our former family into two residences simply requires more resources-- as is indeed obvious to anyone who's been through it. Food for thought: family size matters. While having fewer children in order to reduce population growth, for instance, is an admirable personal or national aspiration, smaller families will only prove an ecological boon if they do not simply appropriate the same amount of living space formerly occupied by larger families.
Some other calculators, if you enjoy playing with the details:
The Inconvenient Truth CO2 impact calculator. Note that "average" here means U.S. average.
The World Wildlife Fund Footprint Calculator. It's more detailed than the two above; on the other hand, it is difficult to use at first (it does not appear to register your choices-- be patient and trusting, it really is working) and is clearly designed for a British audience (if you need help with unit conversions, I recommend onlineconversions.com). There is also a strange moment in the middle where it appears to turn into a marketing survey.
The Lifecycle Climate Footprint Calculator, from the Berkeley Institute of the Environment. Also check out the U.S. average vs. world average bars at the bottom of the page. This one is very cool, once you get used to the click-and-drag interface-- the calculator provides the national average answers in the spaces provided, and then you drag the numbers upward or downward to represent your own lifestyle. Highly recommended. Interestingly, my results from this much more detailed calculator were generally similar to those from the simple Earth Day calculator: 2.3 times the world average greenhouse gas emissions (in this case), but less than half the U.S. average.
Enjoy. Or quake with guilt, or both.
[update] related link: A. Siegal, over at Daily Kos, gives us a list of resources for talking to children about global warming.