VTCifer

my carbon footprint is probably pretty small compared to someone who commutes two hours in a car by himself or herself every day.

Just FYI, probably not.

Just to get to Platinum, you have a carbon footprint of an extra 13,875 kg of CO2. (note this is using the best possible figures).

Assuming a 23 mpg car(2013 average), a person generates 0.387 kg/mile. Your subway ride generates 0.163 kg/mile. Assuming all other things equal (daily driver commute vs walker + subway), this is a difference of 0.224 kg/mile. With your extra 13,875 kg, this means that in order to break even, you'd both need to be traveling ~62,000 miles year in your commutes. This is a 248 mile daily commute (124 mi one way).

tl;dr Use Skype more.

(Source for figures)

That's a value judgement. I should have said:

tl;dr: Use Skype more if you are really concerned about your carbon footprint.

edit: I'm well aware of the impact my travel has. I try to do my work remotely as often as I can (else I would literally be flying every week, or more) I just don't like the assumption that "Oh, I take the bus and walk, this cancels out my flying", without actually looking into it. People make judgments like this all the time, without anything to back them up.

Know the numbers.

I've started having to travel more for work (sometimes 2x a month cross-country, sometimes out of country.) Any suggestions for getting started in this process? It seems interesting to me.