Should cars be banned from the city-centers?

Should cars be banned from the city-centers?
In the 20th century people began pollute our environment and nature by million of manufactures and factories. But if we can close some of these manufactures, we never can stop using cars in our everyday live.
From every car through, for example, more, than 700 kilograms the carbon dioxide in year. And the car’s number grows and grows up! And now we have only one question: „How can we save our nature?“
One on the decisions of this problem is to bane cars from city-centers. It’s possible only in this way, when there are more public transport. In this way there are some good things. One of them is that the government will save money of using the public transport. And from this they will get some money. And, of course, the nature will be a little save.
In the other hand, this is very, very and very small step to save nature. Every person must understand this! And every person, who live, work or study in city-center must use public transport, what isn’t very comfortable.