Maybe you can explain to me then how it is that this makes a significant difference in global warming. The carbon that is released by cows and humans after consumption of plant matter was derived from said plant matter. The carbon in those plants came from the air. Hence, this is a closed system where carbon is taken from the air by the plants, consumed by the animals, and then put back into the air by the animals. There cannot be a net gain of carbon from this. The only reasonable argument I have thought of so far is that of methane, although in theory that can be pulled from the air and used as fuel (whereafter it becomes available to plants again).
The burning of fossil fuels, on the other hand, puts more net carbon into the air since those fossil fuels are being pulled from deep reservoirs that otherwise would be keeping their carbon to themselves. The fossil fuels are being burned far faster than they are being deposited back into the earth, which lacks the balance that the grass-cow-human-air-grass loop has.
I completely agree that transportation should use electricity and related energy sources wherever possible. However, I don't believe this will come any sooner than economics demands it. All the countries in the world cannot be controlled. Just look at all the unsuccessful wars where one country tries to control another's internal affairs. Without the majority agreeing to bite the bullet and use green energy, the first-world nations would become even less competitive than they currently are, making first-world jobs harder to find. Even many of the jobs related to building green technologies would most definitely be outsourced to lower-cost nations who don't follow the guidelines. Outside of fully socialised (zero-profit, public-benefit) production of green technologies, the cost is too prohibitive.
One of the reasons why this topic is rarely discussed here is because people often get very emotional. I hope people can understand that I'm simply trying to point out the problems with non-socialised green. Please don't shoot the messenger, as I care about the environment more than the average person; but that doesn't give me or you magical powers to make people stop using fossil fuel.