World Population 2100

[trm1958]

What will be the human population on the last day of the century?

[trm1958]

Disclosure:
I voted 4-6 G...I've always been a cockeyed optimist 

[SteveMDFP]

What will be the human population on the last day of the century?

How do I vote if I think all options are approximately equally plausible?

[RunningChristo]

My yongest will be 96 then, so I will try convince him both to stay alive and also keep an eye on this site😉.

We'll pass the 8 billion mark already next year, so I choose 8-10 Bill, supposing we will have peaked the top well before 2100.

But Who can predict either technology, pests or other obstacles 78 years in advance?

[trm1958]

Don't worry, I won't come after you January 1, 2101 and go "neener-neener" if you vote wrong. For one thing, as you see by my name I was born in 1958, and so would presumably need a Spiritualist Medium to do so! 
I suppose StevenMDFP can abstain, or go "Eenie minnie miney moe".

[SteveMDFP]

Don't worry, I won't come after you January 1, 2101 and go "neener-neener" if you vote wrong. For one thing, as you see by my name I was born in 1958, and so would presumably need a Spiritualist Medium to do so! 
I suppose StevenMDFP can abstain, or go "Eenie minnie miney moe".

Maybe add an option of "No friggin' clue"  The number could easily be 10 billion or zero, in my mind.

[SimonF92]

I quite like this when im looking at world pop

https://www.worldometers.info/world-population/

[zufall]

https://www.smh.com.au/national/world-population-to-peak-and-decline-sooner-than-previously-thought-20220710-p5b0ik.html

Here is a book review of Alfred McCoy's "To Govern the Globe":

https://theraven.substack.com/p/climate-and-the-collapse-of-world

I'm mentioning it here because it touches on the often ignored possible effects of global warming on world population:

Much of the world proceeds with business as usual assumptions, largely ignoring the impact climate disruption will have incoming decades. McCoy does not make this mistake. His analysis of climate as a central factor in the global geopolitics of coming decades is a seminal contribution.
(...)
McCoy spends the final pages of To Govern the Globe citing many projections of coming climate chaos, including “worst-case” sea level rise projections of 5.8 feet by 2100. Even at more moderate increases, 150 million people will be below high tide by 2050.  Uninhabitable hot zones will spread from the current one percent of the Earth’s land surface to 20% by 2070, “placing a third of the world’s population, or about 3.5 billion people, outside the narrow niche of temperatures that has sustained human life for the past six thousand years.”

[Rodius]

I won't be higher than it is now.

And given the environmental collapse we are watching right now, and it has only just begun, I can see the population being below 2 billion.

I am not sure how, if we are going to accept the concept of consequences over climate change, how anyone can be so optimistic that they think it will be over 5 billion.

Or maybe I am just being pessimistic?

[crandles]

Since UN population Prospects 2022 mentioned



95% prediction interval ~9bn - ~12.3bn

I think that range should definitely be wider, and perhaps a little lower (I went for 8-10bn poll option) but a sensible 95% range could easily be as wide as 1bn-15bn. I think I would rather be a bit more optimistic and suggest more like a 6-12bn for a 95% probability range but I have low confidence about that.

[Rodius]

Since UN population Prospects 2022 mentioned



95% prediction interval ~9bn - ~12.3bn

I think that range should definitely be wider, and perhaps a little lower (I went for 8-10bn poll option) but a sensible 95% range could easily be as wide as 1bn-15bn. I think I would rather be a bit more optimistic and suggest more like a 6-12bn for a 95% probability range but I have low confidence about that.

The projections assume that business as usual continues.
IF that is possible, these projections will be correct.

But ignoring the upcoming and significant challenges is ignoring the situation we are in. Personally, I think we are near the leak of human population between now and the next ten years. Then it is downhill from that point on.

[gerontocrat]

I went for 2 to 4 billion.

My guess is that humankind will get there the easy way or the hard way.

The easy way is to encourage sub-replacement fertility (already existing in many countries), embrace automation as a substitute for labour, and taking global heating and environmental degradation seriously.

The hard way is BAU (growing population and growing GDP) until humankingd has trashed the joint (i.e. severely compromised the ability of the planetary systems to support carbon-based life forms). BUT if the planet has a reduced ability to support life, then life has to reduce. BAU means humankind and its domestic animals are protected, the rest of life... ho hum. Collapse in planetary systems phase 2.
Outcome? Nasty.

At the moment we are careering along the hard way.