Cheerio 4 Billion Humans

There was some Scientist on the radio this morning and he said that the World contained 3 trillion trees. My first thought was how the hell could he know that and assumed he must have a whizzy spreadsheet or something but it was what he said next that got me thinking which was that to balance the amount of Carbon Dioxide we so stupidly spew into the atmosphere, we would need to double that amount to 6 trillion trees.
Trees are big so that is a lot of land needed so my brain went we could plant twice as many trees or alternatively, we could always just get rid of 50% of the 8 billion humans but which nations should we wave goodbye to?
We could go the most polluting ones so that would be China (population 1.4bn), the United States (347m), India (1.4bn), the European Union (450m), Russia (143m) and Japan (123m) which totals 3.9bn so that's close enough so that's sorted but then maybe we should look at it historically, bit harsh to get rid of nations because they are the biggest polluters in 2025 when there were plenty of other poisoning the Planet before them so let's tweak the criteria slightly and see if we cant get two birds with one stone and get rid of the most hostile and violent places that blight us.
The Peace Index is where we should turn here so to get to the 4 billion humans we need, and according to my calculator, we would have to wave goodbye to every nation under position 97 in the Peace Index so once again it's bye to some large populations such as China, USA, India, Philippines, Egypt, Bangladesh, Brazil, Mexico, Ethiopia, Pakistan, Nigeria and Russia which is a good portion who are also the Worlds largest polluters so everyone is happy, well the ones not living in those countries anyway because while the rest of us are living in a cleaner and less warmongery world, they are going to be escorted from the premises.
Just remember that the last one out, make sure you turn off the lights, we are all about saving energy and all that.