A 50 minute car commute becomes a 2 day haul by pony and trap.

http://news.bbc.co.uk/1/hi/england/devon/8264775.stm

I wonder how much carbon dioxides were generated in:
- producing food for the horse
- produced by the horse
- produced during the caring of the horse (how much to build stables, transporting water, generating medicines etc)
- produced in the manufacture of the trap

I'd imagine in an earlier time, such a trip could be done in a few hours. In fact, I've just looked it up. Horses generally do 40mph at full pelt (50mph if in short bursts). A 39-mile trip would take roughly an hour provided it was a straight line and the road was suitable.