I once calculated my carbon footprint. It was enlightening, but not very useful.

1. Your airline travel depending on how many trips you take is perhaps 90% of your carbon footprint. If you don't want to create carbon, don't fly on planes.

2. Your energy come from a source. In Seattle it comes from hydroelectric, which has no carbon emissions, while in New York it comes from coal, which is high. This is the second most important factor.

3. Car travel. This is easy to calculate.

4. Food. If you eat meat, you will have a high carbon footprint. Vegetarians not so much.

There are other factors obviously, but these four are about 95% of the average person's consumption in a year.