A 2,500-mile radius in Asia contains half the world's population (2017)

[dntbnmpls]

Total world landmass: 57,510,000 miles squared.

https://en.wikipedia.org/wiki/List_of_countries_and_dependen...

2500 miles * 2500 miles * pi = 19,630,000 miles squared

So that area represents about (19.63 / 57.51 ) 34% of the total world landmass. So 50% of humans live in 34% of the landmass. But harsh and relatively uninhabitable lands make up a large portion of the earth's landmass

( antarctica - 5,400,000, siberia - 5,100,000, canada - 3,511,023, australia - 2,947,336, , greenland - 836,330) = 17.8 million square miles.

So the habitable areas are 57.51 - 17.8 = 39.71 million miles squared.

So that circle represents ( 19.63 / 39.71 ) 49.4% of the habitable land.

So in the end, about 50% of the world population lives in about 50% of the world's habitable land.

Astounding huh? It's amazing what some math and common sense and understanding of geography takes away from a clickbait article based on a reddit post.

As others have noted, that area is also primed for human habitation due to tons of fresh water rivers flowing from the tibetan plateau and rich fertile land along with year-round planting seasons due to its proximity to the equator.

[olalonde]

So that region is not more densely populated than the rest of the world? That makes me a bit skeptical of your math because it obviously is. For one, you are using habitable land mass for the rest of the world while the circled area is mostly sea water. I wonder how that comment got to the top.

[Aperocky]

The circle contains 1/3 ocean and ocean is not landmass. You'll have to revise your calculation. Also, since the circle contains Tibet, desert in Xinjiang and Mongolia, your assumption that all of that is habitable land is even more wrong.

[rjkennedy98]

It clearly says " 2,500 miles in diameter" which makes it 1,250 mile radius.

pi * 1250 *1250 = 4,908,738 square miles or ~5 million square miles.

That is < 10% of the earths land mass.

[theredlion]

> Myers was amazed to find that a circle roughly 2,500 miles in diameter, when placed over the right part of Asia, could hold more than half the world's population.

The above is from the article. It says radius in the title and diameter in the article

[Merrill]

A history of population within the circle would be interesting.

The population of China since 2000 years ago appears to have been a series of plateaus with brief periods of increase and a couple of brief decreases. The plateaus represent populations at the limit of agricultural systems. The increases are due to introduction of new systems, such as rice cultivation further north, double-cropping of rice and so forth. The decreases are periods of famine, disease and war. http://www.china-profile.com/data/fig_pop_0-2050.htm

Possibly other civilizations within the circle follow the same pattern of stability, innovation and crises.

[code_sloth]

52M km^2 of land on our planet is habitable, after forests, shrubs, rivers and lakes [0]. Total land mass is 149M km^2. So only 1/3 of the world's land is habitable. That's actually ~20M square miles. Your habitable land estimate is already nearly 50% off according to the source I found.

The circle covers 50.2M km^2 (4000^2 * pi). I'm going to assume the 2/3 land quotes are good enough an estimate. That makes the land mass inside the circle 33.5M km^2 (2/3 * 50.2). That means that the circle contains just 22.5% (33.5M/149M) of ALL land mass.

I couldn't find any quick data source on how much land inside the circle is actually habitable. So I'll apply a few ratios:

If X% of the land in the circle is habitable:

  X = 33% --> 33% * 33.5M / 52M = 21.5%  
  X = 50% --> 50% * 33.5M / 52M = 32.2%  
  X = 75% --> 75% * 33.5M / 52M = 48.3%

Your estimations would hold iff >75% of the land in the circle is habitable.

[0]: https://ourworldindata.org/land-use

[empath75]

1/3rd of that circle is water. And a significant amount of it is also Siberia and Mongolia. Double check your math.

[dilippkumar]

> 2500 miles * 2500 miles * pi = 19,630,000 miles squared

> So that area represents about (19.63 / 57.51 ) 34% of the total world landmass. So 50% of humans live in 34% of the landmass.

I've been telling myself that I have to teach myself Non-Eucledian Geometry, but lacking any real motivation, I've successfully procrastinated for 6 years.

The unfortunate itch to be pedantic on the internet will hopefully drive me to learn how to correctly calculate the area of a circle on a sphere.

Anybody has a good textbook recommendation?

[jariel]

"So that area represents about (19.63 / 57.51 ) 34% of the total world landmass."

1/2 of said circle is ocean, not land. And some of said land is 'uninhabitable' i.e Gobi Desert.

And Canada is 3.8 miles squared, implying that 3.5 of those are uninhabitable is rather off. By that calculation, you'd be excluding most of Quebec and Ontario, which are 'inhabitable' just sparsely populated, in which case much of Tibet and China would be comparably 'uninhabitable' as well.

[speedgoose]

2500 miles ≈ 4000 km.

Guys, switch to metric units already. Thank you.

The rest of the world.

[aldanor]

While I live in Europe and I do agree, imagine how nice would it be if the entire world used the duodecimal system today for everything, i.e. 100 was preceded by BB (143). Greeks and Shumers were smart guys - 12 has 4 divisors (excluding itself and 1) while 10 has only 2. Same story with 100 and 144, etc.

[ikeyany]

I find it very interesting that a large portion of the UK uses yards to measure distances shorter than a few kilometers. I saw a sign that read "Exit - 500 yards" in London the other day.

[VvR-Ox]

YMMD :D

I wonder when the day will come that humanity overcomes these issues without the need to convert values between several systems all the time.

[anonu]

Is there an imperative to do so? Don't get me wrong, I would love for everyone to use MKS.

But the cost of making that switch maybe far outweighs any gains.

[nojvek]

A litre of pure water weighs 1kg at sea level. A litre is 10cm x 10cm x 10cm. Water freezes at 0 and boils at 100. Volume, distance, temperature as wonderful easy to remember units.

Sincerely, metric system and friends.

[blackrock]

I must admit, I find it baffling how the EU uses metric, but yet, they use the comma as the decimal point. And the dot to separate thousandth units.

Like this:

1.000.000,52

Why is that better than this:

1,000,000.52

[throwGuardian]

Part of the reason is the Ganges & YangTse river deltas are the most fertile on Earth. While other regions typically yield 2 crops a year, these deltas average 3 to 4.

Also, the climate is relatively moderate with no major high frequency calamities (like earthquakes and hurricanes).

[contingencies]

Don't forget the Brahmaputra, Irrawaddy, Salween, Mekong, Red River, Pearl River, whatever dominates Java/Sumatra...

[emmelaich]

> .. no major high frequency calamities (like earthquakes ..

And yet, it is one of the most geologically active areas on earth. The Ring of Fire, Deccan Plateau, bunch of volcanoes.

I'm sure this has a lot do with it's fertility.

[blackrock]

This must be why the Mongols dreamed of conquering China, and finally succeeded. To control access to this ancient agricultural production system.

And why the Chinese were so adamant on building the great walls as their perimeter defense system.

[cortesoft]

I was wondering... they didn't mention reasons at all in the article.

[cam_l]

Reminds me of an awesome map from a few years ago.

http://www.radicalcartography.net/index.html?human-hemispher...

[divbzero]

Awesome indeed. Thanks for the link.

The “other” hemisphere illustrates the strikingly vast expanse of the Pacific Ocean.

[kissickas]

The reddit thread (where it was originally posted) has some good discussion.

https://www.reddit.com/r/MapPorn/comments/1dqh7d/after_seein...

[abbadadda]

Interesting discussion there on climate and geography (in the vein of Guns, Germs, and Steel). Thanks for linking.

[stickfigure]

A 3,958.8-mile radius around the center of the earth contains 100% of the world's population.

[divbzero]

This noteworthy point can help our intuition.

     πr² = area of circle
    4πr² = surface area of sphere

Thus a 2,500 mile radius circle covers ~10% of Earth’s surface.

[tim333]

There are quite a few in planes and up mountains.

[quickthrower2]

Astronauts?

[andys627]

A 30 ft radius in Davos contains half the worlds wealth

[symplee]

*Spherical cap

https://en.wikipedia.org/wiki/Spherical_cap

Bonus points for whoever calculates the ratio of the surface areas for the two spherical caps that contain half of the human population. (The circle's radius is ~4,000 km)

[dmix]

Intestestingly in the original Reddit thread they were talking about epidemics as around that time (2014 was the post date) the influenza H7N9 was hitting China, which was also impacted heavily by Chinese new year travels. Smaller rates than Corona but it still hit 1223 people and had a 30-40% mortality rate:

https://old.reddit.com/r/MapPorn/comments/1dqh7d/after_seein...

https://en.wikipedia.org/wiki/Influenza_A_virus_subtype_H7N9...

From what I understand influenzas tend to be the scarier than Coronavirus types of viruses in most projected pandemic scenarios.

This is one of the downsides of high density areas, although for more cost effect for lower income people so density will only continue to grow in most of the world.

[billfruit]

Beyond the factoid, the article unfortunately does not delve into why the population is concentrated in such region. Especially India, Bangladesh, Pakistan, that is most of the subcontinent has very uncomfortable weather, but still is highly populated, I wonder why? Why didn't people in the early ages decided to move to more temperate climes?

[OnlineGladiator]

At first the article says it's a 2500 mile radius, and then it says it's a 2500 mile diameter. So which is it?

[iancmceachern]

I was just reading this interesting article on the topic. I particularly like the graph if population vs latitude.

https://www.quora.com/Why-are-countries-like-India-and-China...

[est31]

Note that the title is wrong. It's a circle on a map, not in real life and thus it's not a "2 500-mile radius". A sphere in real life would be distorted in the map. In fact, all the meridians and circles of latitude are circles in real life but on the map they don't show up as circles.

[cortesoft]

They don't talk at all about why it is so. Is it particularly fertile territory that can support this kind of density? Is there something about the geography of the area or the geography of the globe that makes it have so many more people than the rest of the world?

[fizixer]

2500 mile radius is no joke though.

It's 10% of world's land area.

edit: The circle in the article has plenty of water. I'm not counting that. So maybe land area in that circle is 5% of world's total land area (not 10%).

[archivist1]

It's centered on the island of Hainan. I want to know what the center of mass is for that picture, since the humans are not uniformly distributed in that circle.

[tomq]

A detailed follow-on study found a 4,000-mile radius sphere centered on the earth’s core contains ~100% of earth’s population. Scientists stunned.

[wsxcde]

This will likely change once Africa becomes the most populous continent, which is expected to happen somewhere around 2100.

[dehrmann]

Guess that means more more than 2% of humans to have ever lived live in that circle.