But in the end it still wont help to keep the big bad "Global Warming" away. All this would help is reduce pollution in cities so it would be more healthy. Human, even with all the cars and factories causes very little percent of all pollution that causes global warming.
I mean, cows for example probably cause as much, and more pollution with their gas that human with cars.. Now, there is a lot more animals than cows. You cant kill all of them all or make them drink "Better gas". You probably even could put some stuff in cows food, but not all of them.
This is, and always been like that. Earth has had global warmings and ice ages in the past and will have in the future, thats just how it is. "Normal" -> Global Warming -> Ice Age -> "Normal".
We're getting too overcrowded anyway..
Just stay back and enjoy the new scenery that ice age brings us