Unused land?
Excuse but since when are we the owners of the Earth and it's lands?
It's otherwise, the Earth owns us, and nature by itself has shown us that.
The fauna and flora of our planet also needs its own space, nature itself does.
Ecosystems are essential to the planet, and overpopulation is killing this.
Overpopulation is a problem, as it creates the need more resources, economy per family, more food, more space, more jobs, more pollution and contamination, etc.
With the increase of technology, jobs are getting scarce by the day, and no, technology is not to blame, it's humankind by itself who is to blame.
People fuck left and right without a care in the world if they have 3,4,5 or whatever kids.
Also, take into consideration that the standard life-span of most countries is now above 70 years old.
That means there are a lot more generations alive living with each other than ever before.
This extends the meaning of overpopulation.
My suggestion to counter this kind of issue would be to make laws that limit how many children a married couple can have.
Similar to that of China, you can take China as a clear example of overpopulation.
Makes sense.
How many people are usually involved in a marriage? Two right?
Then let's set the limit of children to 2 per married couple.
Two for two, makes sense.
Once the elderly couple dies, only the two children are left.
Of course doesn't take into account the increase in life quality we are getting, but would be a huge improvement.
I can also guarantee you, that most families would have a better economy.