If humanity lived at the density of Wyoming (5.97/mi^2), we would have to get rid of 50% of the U.S. population or 98% of the world population, because only 147M people could fit on the habitable land on earth.
So yes, it is and it isn't. The question is how many people want to live in Wyoming-level densities vs. Paris-level densities, given the elimination of any cost constraints.
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.
You could also (in theory) put every human on Earth in Texas with a population density of only 26,000 people per square mile, about the same density as New York City.
If we have 54 million square kilometers of habitable land that is not used for agriculture, and we scatter 8 billion people across it, then we end up with a population density of about 148 people per square kilometer -- which is approximately what Florida is today.
> If everyone lived in cities as dense as portland, the current human population would only be living on about 2.7% of the world's land mass.
What is the human population's current footprint? Wikipedia says humans' average population density worldwide (excluding Antarctica and oceans) is about 50 people/km^2.
If you moved the entire population of the Earth to the United States and spread it out evenly, there would only be about 2000 people/square mile (7% as dense as New York City).
So not overpopulation as much as everyone wanting to live in/go to the same handful of places. And now they are all mostly making choices based on the same sets of data (Yelp reviews, AirBnb etc etc).
Just out of curiousity I let Wolfram Alpha divide the total land area by the global population and got roughly 0.0191sqkm per person. That’s about a 130m distance if people were positioned on a grid.
Then I found that roughly 57% of people live in cities. Treating the size of those as a negligible term that leaves us with roughly 210m. Then I found that 57% of land is considered uninhabitable which cancels out the city factor, so we are back to roughly 130m. I think this is a neat number as it really puts being kilometers or even tens or hundreds of kilometres away from others into perspective. The human density distribution on earth is really all over the place.
With a maximum estimated population of a few millions living on 7 million square kilometers, that's not really a great path to follow for Earth's current 8 billion inhabitants sharing about 150 million square kilometers.
I found the "If everyone lived as densely as..." hard to parse. A better way to say it is: "To give everyone as much space as the average Alaskan has, we'd need 108 Earths."
But it's not like you get that automatically just by having a giant mass of people. There needs to be a certain life-style and culture to create those things. What density of humans is ideal for that?
The calculation shouldn't just be, "what's the maximum # of people we can physically support on earth?" It should be, what's a nice number that makes life pleasant and fulfilling and leaves time for leisure?
And while the earth is very large, the number of places that are truly special is much smaller.
For example, if you look over the whole earth, what fraction of it is at the level of, say, the San Francisco Bay Area, for sheer natural beauty and enjoyability of surroundings?
A small fraction indeed, I would say!
(Of course there is some room for personal preference in here; maybe you're a desert person or whatever. But though squishly defined, the point still stands.)
Today, it's expensive and stressful to live in the Bay Area, because of overcrowding.
But look back at say the middle of the 20th century -- it was still an amazing, beautiful place, but it was much less crowded and much less expensive! This provided fertile ground for interesting artistic and cultural movements, like the beats & their poetry & the hippies & their music.
Now it's much harder to have those kind of cultural and artistic movements in SF, because just basic physical survival is much more of a struggle.
I looked up some context out of curiosity. Siberia appears to be home to 40 million people (half a percent of the world) now, living at a population density of five Palace of Versailles per person. Antarctica isn't doing as well, with only 1--5 thousand people at a time.
Millions of people live on land that was formerly water. For example, many people in the Netherlands live below sea level. A sixth of the current land mass of the Netherlands has been reclaimed. Of course, worldwide it seems that only slightly more than about 1% of 1% of land is reclaimed.
Not many people literally live on water, but it seems that the worldwide total is at least 100,000 (or a small multiple thereof).
Estimates of what portion of the land on Earth is "habitable" varies, but is usually about half of the land. At that rate, we would have to share each Palace of Versailles with all of 5 other people.
In other words 100 billion to 1 trillion. The world’s land area, excluding Antarctica, is about 50 million sq. miles. With a comfortable population density of 1000 ppl/sqm (like in South Korea, Holland, Israel, or the state of New Jersey) you would get to 50 billion (same as Trantor). The population density of Singapore is close to 20k ppl/sqm, that would give you 1 trillion.
If you are willing to pad the Earth with buildings 16 km high, you could pack at least 1000 times more people, more likely 1 million times more.
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.
So yes, it is and it isn't. The question is how many people want to live in Wyoming-level densities vs. Paris-level densities, given the elimination of any cost constraints.
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