> When taking all studies into account, the best point estimate is 7.7 billion people; the lower and upper bounds, given current technology, are 0.65 billion and 98 billion people, respectively.
> the lower and upper bounds, given current technology, are 0.65 billion and 98 billion people, respectively.
The answer is "anywhere from a tenth of the people currently alive to 13.5 times as many as are currently alive." Absolutely useless. A range covering more than two orders of magnitude. May as well say, "We don't know."
Not at all. To say "we don't know" might mean that we don't know the order of magnitude. Order of magnitude estimates to the first or second decimal place are oftentimes more than enough to hone in on a solution. In this case the two orders of magnitude set a clear bound (assuming the capacity estimate are accurate) for the near future at the high end and provide a warning sign for the present.
This is a meta-analysis. They reference many different papers. Many of them come to different conclusions. If you want more certainty you can get it by starting to read the papers the reference and deciding which ones you think are reasonable.
Well if we have 98 billion people on earth - lets see how dense we get. This [site](http://www.zo.utexas.edu/courses/thoc/land.html) argues there's about 24,642,757 square miles of habitable land on Earth - this is discounting deserts and mountains, and of course oceans.
That puts about 6 people per acre in all the habitable spots on the globe.
To put that into perspective, Manhattan has about [27,000](https://www1.nyc.gov/site/planning/data-maps/nyc-population/...) residents per square mile - or 42 people per acre. There are other, denser cities out there as well. People-dense parts like this make other parts more people-sparse.
I'm sure by the time (if) we have 98B people - Manhattan will be much more people-dense, and many more cities will be similarly dense. So it may be that 50B people live in massive, dense cities, leaving the other 50B to be in more suburban-yet-still-dense zones.
However, this is the 'idea' case of all habitable land being used for habitation. There is also the need for farms and industrial land, and all manner of other places for human activity, and the vast things needed to support it. Ideas like vertical farming solve for some of these, but are not perfect.
98B might be possible if we did everything perfectly efficiently and optimized every single part of the planet leaving absolutely nothing allocated for the bare essentials to keep people living. The reality is we would never get anywhere close to that level of efficiency and would destroy the planet much sooner.
At Dutch population density (1,312 people per square mile[1]) that would be 32 trillion people so even 100 billion people should leave plenty of space.
Would AR/VR help with this at all? I was thinking that with the earlier article about Japan's micro apartments, if having the walls covered with 3D screens (or even mirrors) would give a bigger sense of space and help with mental well being.
I can say from experience that VR absolutely helps dispel cabin fever. I once lived in a fairly small apartment in a dense city. Turning on a big box fan in my VR area and then going out to wide open spaces like the mountains in Skyrim VR made me feel better almost instantly.
Seems likely, if you decided to dive into the various papers they are pulling from I'd be really interested to hear about which ones consider sociological problems like emotional effects of over crowding!
https://academic.oup.com/bioscience/article/54/3/195/223056
> When taking all studies into account, the best point estimate is 7.7 billion people; the lower and upper bounds, given current technology, are 0.65 billion and 98 billion people, respectively.