I took the challenge and am disappointed by the results:
Your annual carbon emissions are 36,611.2 lbs.
That's equivalent to the emissions from 3.59 passenger cars.
Average carbon emissions per year, per person:
United States: 44,312
I rarely drive, use a canvas bag for nearly all purchases and compost our yard waste. Yet, I was only 25% better than the average American. I think my above-average amount of air travel contributed heavily to my carbon emission score. I'll have to look into Terrapass.