Taking the bus instead of the car to work will "pay for" like 4 cross-continental trips a year. If you take a bike instead, it's closer to 10.
Only if you want to maintain the same levels of unsustainable CO2 output. That's totally unacceptable. We need to get to as close to zero emissions as we can as fast as we can, which means taking mass transit to work, living closer to work, and not flying so much.
> Driving the same trip is 2500 pounds - more than 4x.
Not if you do it in an electric, sustainably powered car (or better yet train).