Carbon and carbon taxes

 Facts
Many years ago the world leaders reckoned the earth was flat.
Today the world leaders reckon there is more carbon than there was in the days of Jesus.
So the existence of a carbon tax.
As we all know history repeats its self and the world leaders were proved wrong that the earth is not flat.
The world leaders have got it wrong again there is the same amount of carbon on the planet as there was when Jesus was a boy so why the carbon tax?