As a person with a below average carbon footprint of about 6000 I found that my transportation number was quite low at about 800. I was expecting a lower number since I bike everywhere, but what I was not expecting was my peers overall massive numbers. They were extremely high and the main contributing factor to most of their overall carbon footprints.

According to the 2001 National Household Travel Survey by the US department of Transportation about 2.5 billion miles a year are driven just from trips over 50 miles from home. If the average passenger vehicle emits 411 grams of carbon per mile than about 1,027,500,000,000 grams of carbon are released per year just from trips over 50 miles by car.

I barely go anywhere.  Home, college, daycare, and my daughter's speech therapy.  But I still had a large Transportation footprint at 1355, and my region holds 3447.  It is massive, especially for vehicles.  But you are correct, a bike is even more surprising.

I agree with Matthew, transportation can be a main contributor to the great levels carbon in the atmosphere. After receiving the results of my carbon footprint, I realized there were changes that needed to be made to lifestyle. For me, the transportation portion had the highest amount of carbon emission into the atmosphere. This was likely due to the high amount plane trips I took in the past year. Many of these plane rides I took were not necessary and I did, for example, watch my brother play baseball in San Diego twice in the previous year was not necessary. According to Elizabeth Rosenthal, a writer for the New York Times, a flight to Europe from New York would compensate for three tons of excess carbon in the atmosphere. This implies that air travel contributes to a high percentage of carbon emissions. Rosenthal also states that aviation is responsible for 5% of carbon  Therefore, if people reduced their airplane flights, carbon emissions would drop significantly. This informations keeps me mindful about my contributions to the environment.
            Another poss ible way to take action in limiting the carbon in the atmosphere is to spread the word to friends and family about being conscious about how their daily choices affect the environment. For example, suggest that every morning when brushing their teeth, remember to turn of the faucet when it is not being used or to turn off the lights when no one is in the room. Another way to lower your footprint is to purchase more LED light bulbs in place of incandescent bulbs. If everyone takes art in small changes, together the total impact can be huge.