You know how you can come across some cute little tip in the world that you then realize that it is actually one of your favorite past times? That is how I feel about mass transit.
The idea, take the bus/train/subway/carpool to save CO2. Great idea right? Save the world! Yep, the world....
Did you know that the buses run no matter if you are on them or not? As do trains and subways and all sorts of mass transit. Most likely cars you go in with a carpool do as well? I once had a friend who drove us on a long trip that we tried to pay him for gas and he wouldn't accept our money, he would have drove up anyways.
There we hit it! The money. Now, I'm sorry if you have to pay for entry to a bus, but gosh, the price of owning a car is probably more. I do not have to pay. Ever since I started college the local mass transit system has given college students free passes. So I started to take the bus instead of spend money on gas. I walked about a half a mile a day just to take the bus. I got a nice exercise out of it. I then killed my back and I couldn't walk that far anymore, so I stopped.
I have now transferred to the university and have a much farther way to go. Instead of that gas money to go all the way up to school and fight for a parking space, I take the train. Sometimes it is the only reliable way to get to school. It is actually closer to my building than parking would be. I save money and energy, but my favorite part is the sleeping. I sleep on the train, my body has actually figured out how long it takes to get to school and won't sleep past that, much. I get an extra hour of sleep that I wouldn't if I had been driving. Some people even read, but I am not one of them, I get motion sickness.
I have one friend who thinks I am crazy because I actually have friends that I have made on the train. I am stubborn and like seats and this one lady sat in the wheelchair area with a perfectly good seat next to her. I decided I would sit there, and did daily. When she finished her book she was reading, we started talking and are now friends. I also have another friend who met his wife on the train. My friend calls it my 'social hour' and she is right, sometimes that is the only time I have to just sit and talk to someone. I wouldn't give up my train friends for a car.
So yes, save the world. Or better yet, save your money, time, energy, and live a better life.