How many trees are there?

An interesting article came out today suggesting there are three trillion trees on our planet, of which 15 billion are removed each year by mankind and only 5 billion replaced. This significant annual deficit is unsurprisingly thought to have consequences on climate change. To emphasize this point it is estimated that since the last ice age 11,000 years ago, human kind has been responsible for removing three trillion trees. So, on this data, we are now halfway to stripping trees away from our planet entirely. Dismissing the figures, which could be wild estimates, the trend remains very alarming.

At present there are approximately 420 trees for every person on the planet, but with the population rising and trees stocks annually being eroded, we are potentially walking gently to hard times ahead. I wonder where and when the tipping point will be?