Metaculus Help: Spread the word
If you like Metaculus, tell your friends! Share this question via Facebook, Twitter, or Reddit.
Will there be a city on Earth with a population of over 100 million by 2100?
For a mostly hairless, fangless species that was likely reduced to just a few thousand members in relatively recent times by a volcano, we've certainly been busy.
The human population on Earth now exceeds 7 billion. And we're still growing. Not everyone is thrilled by this. But it's reality.
Currently, as of Q2 2018, Tokyo, Japan is the world's largest metropolis, cramming over 38,000,000 people (give or take) into its borders.
But by the end of the century, we could (and probably will) witness far grander cities.
Per Canadian demographers, Daniel Hoornweg and Kevin Pope, for instance, Lagos in Nigeria may swell to 100+M by 2100 if trends continue. Face 2 Face Africa has the story:
By 2100 if Nigeria’s population continues to grow and people move to cities at the same rate as now, Lagos with its current 20 million people could be home to more people than the state of California.
The demographers' full paper is here.
The International Institute for Environment and Development goes into detail about why Hoornweg and Pope are so bullish on Africa here.
Whether it's Lagos that claims the crown or some other city in Africa or elsewhere, what do you think? Will some metro hit 100M people by 2100? (For the estimate we will include the general metropolitan area rather than the strict city boundaries, as done here)
Metaculus help: Predicting
Predictions are the heart of Metaculus. Predicting is how you contribute to the wisdom of the crowd, and how you earn points and build up your personal Metaculus track record.
The basics of predicting are very simple: move the slider to best match the likelihood of the outcome, and click predict. You can predict as often as you want, and you're encouraged to change your mind when new information becomes available.
The displayed score is split into current points and total points. Current points show how much your prediction is worth now, whereas total points show the combined worth of all of your predictions over the lifetime of the question. The scoring details are available on the FAQ.
Note: this question resolved before its original close time. All of your predictions came after the resolution, so you did not gain (or lose) any points for it.
Note: this question resolved before its original close time. You earned points up until the question resolution, but not afterwards.
This question is not yet open for predictions.
Metaculus help: Community Stats
Use the community stats to get a better sense of the community consensus (or lack thereof) for this question. Sometimes people have wildly different ideas about the likely outcomes, and sometimes people are in close agreement. There are even times when the community seems very certain of uncertainty, like when everyone agrees that event is only 50% likely to happen.
When you make a prediction, check the community stats to see where you land. If your prediction is an outlier, might there be something you're overlooking that others have seen? Or do you have special insight that others are lacking? Either way, it might be a good idea to join the discussion in the comments.
Embed this question
You can use the below code snippet to embed this question on your own webpage. Feel free to change the height and width to suit your needs.