As of march 2016 the number of humans alive in the world is that 7.4 billion people, but what if every single last one of us everybody watching this video including you all lived together in the same city. How big or small with this city look like and how close together would we all have to live?
60-percent of us live in Asia while 16-percent live, in Africa ten percent, in Europe eight percent, in North America 5.5 percent, in South America just 0.5 percent, in Australia and Oceania and two little people to even register on the scale in Antarctica.
So first off we would have to agree on which continent or island we would migrate everybody in the world to.
50.5 percent of everybody in the world currently lives in a city, so we would have to convince the other 49.5 percent of people to come and join us.
So now assuming that we have gathered everybody together in the same place to create our city. Let's look at some real life examples to see what living so close together might actually look like.
Singapore is the most densely populated country in the world right now. Five million 399 thousand people live in the small country of just 710 square kilometers. That means that for every square there are seven thousand six hundred and five people living out their lives on average, but singapore is a country the size of a city and there are much more densely populated cities than that already in the world.
For reference downtown Manhattan in New York City has a population density of 26,939 people every square kilometer. That's a lot of people very close together but we're just scratching the surface.
The densest city in the world right now is Manila in the Philippines, where you will find 41,515 people every square kilometer, but Manila is total population is relatively low at just 1,708,000 people. The density of people is just so high because they all live together in such a small space.
The biggest concentration of people in one place anywhere in the world can be found here in Japan. The Tokyo metro area home to 36,923,000 people.
Right now in 2016 the highest concentration of people living in a smaller place than a city is probably within the city of Mumbai, India. Located within the city is a slum called Dharavi which is an area just 2.17 square kilometers in size. If we think about that size and compare it to Central Park in New York City, the Derby slum would only take up 64% of the same size, or not even two thirds of the area, and living in that cramped tiny space or anywhere between 700 thousand to 1 million people. Averaging out those numbers we get 391,705 people every square kilometer. Now this number here is the highest number of people in the world today that live in a square kilometer as recently.
As the 1980s however there was a place that was somehow even more frighteningly claustrophobic. The most densely populated place known in history was the Kowloon Walled City, which was located here Hong Kong. The overall total area of the Kowloon is just 0.26 square kilometers, population 1.2 million per km2. This number is the absolute limit that we've ever seen in the real world of how many people can live together in such a small area.
So now let's visualize how big our hypothetical global city would have to be according to the different population densities that we have been discussing.
First let's imagine something a little comfortable. Let's take the city of New Orleans in Louisiana, whose population density is about 784 people per square kilometer. On that scale our global city would be about the same size as roughly the continental United States. If we moved onto the density of say Austin (Texas) we would be looking at acity that is about the size of Australia.
Then we're going to try fitting everybody into the same density as chicago next. On that scale our city would be about the same size as Iran, but let's get even smaller.
At the density of Singapore, we could fit the entire human race into just the states of Texas Oklahoma and Louisiana. Already considerably smaller than at the New Orleans density but we're going to keep on getting even smaller.
At the density of Manhattan we would be looking at a city about the size of Ecuador, and if we had a city with the same density we see in Manila than everybody in the world would fit inside the U.S. state of Missouri.
But to get even more frightening and claustrophobic our global city with the same density seen within the Darabi slum in Mumbai would be about the same size of New Jersey.
And finally at about the absolute real-world limit if we built our global city with the same population density as Kowloon Walled City, we would fit every single person in the world into an area about the same size as Palestine, which itself is only about half the size of the Tokyo metro area.