What about 40 million - would the improvement be 4x?
The solution may ultimately be a one-child policy, as demonstrated successfully by China.
https://en.wikipedia.org/wiki/Missing_women_of_China
Population control is a very outdated idea, we have enough resources for the population, we just don't know how to distribute them using free market models.
That strikes me as improbable. Globally, you might be right - there is, for example, enough fresh water on the planet for many more people than are alie today.
But moving a lake from thinly populated Canadian wilderness to Niger or Burkina Faso, where the needy populations are, is not technically possible.
And vice versa, Sahara would be a perfect place to generate solar electricity, but the North European populations that would gladly consume it in the winter are too far away.
How is this calculated? Are there enough resources for 8B people go to Tahiti or equivalent destinations for their honeymoon?
Because that’s where the conflict comes in. There might be enough resources to feed everyone some basic meals everyday, but is there enough for everyone to have their own single family detached house with a yard and a couple personal vehicles? Is there enough to ensure everyone can fly around the world to see their relatives or vacation? Is there enough desirable land for people to move to from their currently undesirable land (due to weather/accessibility/availability of fruits and good food)?
Basically my argument, since this thread is quite far down now, is that over-population is not robbing the globe of resources in any amount worth worrying about and therefore population control is not going to solve inequality since it's a distribution problem.
Basically, I’d like to see what quality of life we would have if resources were distributed evenly. I imagine it wouldn’t be acceptable to most people who are used to their spoiled due to the inequality.
https://www.smh.com.au/healthcare/the-missing-girls-never-bo...
"mothers within some key migrant communities are recording sons at rates of 122 and 125 for every 100 daughters in later pregnancies."
The solution is for migrant-receiving countries (ie. the West) to place a limit of 49% males from any one country on any type of visa. This will dramatically boost the intake of females (for some visas and countries eg. India, the intake is 75% male) and thus their value to society in their home country.
Alternatively male migration could just be banned altogether from countries which practice systematic sex-selective abortion.
It turns out that most Chinese couples were allowed 2 children:
https://en.wikipedia.org/wiki/One-child_policy
But there's wide reporting of females being scarce, so some families were involved in female infanticide, which will cause long-term demographic issues.
China is currently facing famine, so we'll see how that affects the population. (It turns out that although China is a communist country, they didn't/don't provide welfare for the flood victims, tens of millions of whom are farmers.)
A more regional problem is that China is damming the Himalayan head waters, so the downstream countries (India, Pakistan, etc.) will face drought on a large scale. Usually that leads to war.