Over 99% of the idea that we are overpopulated is BS propaganda, designed to herd the people into the cities where they can be controlled by big government.
People herd to cities because that's where the jobs are.
You wanna try getting on the London tube during rush hour, you'll understand what overcrowding is.
Fine and dandy. The point is, there is no overpopulation.

LOL, what are you talking about? You cannot just stack people 4 high, squeeze them in and then that's it.
You need infrastructure in place to support them. Our roads here in UK are at breaking point, NHS at breaking point, schools over subscribed. Plus all these extra people use more electricity, water, gas, sewers, the list is endless.
We can't keep concreting over farmland. This provides our food.
The problem isn't lack of land for the population. The problem is that people let their governments run them so that they can't work together to spread out to the available land.
People are all worried about global warming. The truth of it is more like, if the polar caps melted, there would be a little bit of coastal land that would be lost to rising oceans. But Northern Canada, Greenland, Siberia, and Antarctica would open up to easy, fertile habitation. In addition, with extra moisture in the air, places like the Sahara Desert might become a moist, lush jungle.
The problems with global warming aren't the problems. Governments are stating that they are because government people want control.
Several hundred years ago people left Britain to get away from oppression. Today, the oppression is still of the same kind, but it is heightened because of the population problem THERE.
Governments are doing to the people like they always did, because governments are made up of people who want to remain in control, so they can leach off the people.
