The Malthusian model is: more food supply -> more humans -> more food demand -> more food supply -> more humans -> ... A vicious circle. A positive feedback loop. But it's a positive feedback loop operating in machine with negative feedback loops too. It's been over a decade since it's been understood that global human population is going to plateau in just three more decades, then begin declining. Reasons for that are myriad, but if I had to summarize it it would look like this: low child mortality + high life expectancy + high standards of living + high taxes and costs + high retirement costs == low interest in reproduction -- i.e., price signalling works! Who would have thunk it? Not Malthusian modellers, for sure.
Add unsustainable mining/fishing/farming/pollution to feed/dress/entertain all those people with high standards of living.
Now you will see the plateu eventually, yes. But it’s not a natural plateu where we stop because we want chill life, but plateu where we stop because there are no resources (everything is expensive) to support our kids.
My main concerns over the next few decades are cyberwar collapse (< 1% chance), runaway AI (10% chance), robotized world war (30% chance), and solar flare induced societal collapse (40% chance).
Yeah, cereal is 20% more expensive but DeepMind just beat GPT3.
another example - transistors - we've got maybe 10, maybe 20, maybe 30 years of improvements ahead of us, after that there are fundamental limits that forbid progress.
the rate of change of total technology improvements will slow down and at some point will start to approach zero; maybe even go negative as we as a civilization start to forget how to do things faster than invent new ways of doing things.
Robotics keeps improving, eg replacement/enhancement of human labor. That's a paradigm shift.
I definitely see your point about physical limits. I propose that we're nowhere near our ideational limits, which give us the imaginative capacity to form new solutions within those limits you cite.
the problem is, thermodynamics is so generic that it's hard to imagine how to sidestep it - and people do try all the time.
e.g. imagine we have a commercially viable fusion reactor, which translates to basically unlimited energy once you build enough of them that they can be operated and maintained using only fusion power from sister reactors. sounds like post-scarcity world, except if you keep power consumption growing for like 1-2% a year, you'll boil the oceans in a few centuries due to waste heat.
if you invent a technology to capture and repurpose enough waste heat to avoid this problem, you sidestep thermodynamics. if you sidestep thermodynamics, there's a lot more you can do than just making fusion 100% efficient...
For example, power consumption may stop growing even while "real" consumption continues to grow. Or we may spread to other planets so that power consumption can keep growing and we don't care if the oceans boil.
Or something else might happen that is hard to predict in the same way that medieval people would find the Internet hard to predict. Medieval people may have made equally valid claims about bounds on the speed at which a messenger can transmit a message, even if you manage to develop a commercially viable racehorse that can run at top speed 24/7.
Flag signaling between boats is very old and eventually turned into a messaging system that could go 191 km in 5 minutes. Smoke signals where perhaps the oldest form of long distance communication, and was used across the full 7,300 kilometres Great Wall of China. Though actual speeds are less clear.
For physical messages, attaching them to projectiles or birds was also used. A man on foot or a horse had other advantages.
Population is already set to decrease.
Speaking of thermodynamics...
The life-carbon cycle on the planet is not a reversible process. Photosynthetic life, and sea life (sea shells require a lot of carbon) pull down a lot of CO2 from the atmosphere. Sea life in particular leads to carbon being sequestered in limestone over millions of years. Land life leads to carbon being buried in soil. This process trades low-entropy, high-energy sunlight for high-entropy, low-energy light emitted back to space by the planet (keeping us in equilibrium), with the entropy going into things on Earth, like the conversion of CO2 into limestone.
The biggest and shortest-term natural threat to life on this planet is dwindling atmospheric CO2. At the end of each glacial period (thus the beginning of each interglacial) CO2 is lower than at the end of the previous glacial period, and it has been thus since the beginning of the current ice age, and it seems like a pattern that will keep repeating. Eventually the Earth will fall below the photosynthesis starvation level of atmospheric CO2. Before the Industrial Revolution, and the oil&gas revolution in particular, that was going to be just a few more glacial periods. By raising atmospheric CO2 to 400+ppm we've bought the planet a few million years, and even so, if humans were to disappear in the next glacial period, we'd be looking at a closer end to life on the planet through exhaustion of atmospheric CO2 than through astronomic catastrophes like a large asteroid hitting the planet.
It's just a matter of time and survival. How long? I don't know. Probably long.
A gaussian with a really long tail!
We're doomed even if we go inter-planetary -- even if we spread through the galaxy! But the timescales are pretty large, and before then we can have a pretty long (in human scales) and good time.
So, a Poisson distribution?
Our dependence on it all puts us on really fragile ground given that we know there have been sun events in the last 150 years that would obliterate everything we have today
It's definitely at the sweet spot of "terrifying" and "completely plausible."
Here's in-depth info on solar flares. Major ones are considered "Carrington-level events", due to a flare that occurred in 1859: https://www.history.com/news/a-perfect-solar-superstorm-the-...
Vox's 2014 breakdown of the systemic risks: https://www.vox.com/platform/amp/2014/7/30/5951263/a-catastr...
NASA article on the prediction that there was a 12% chance a Carrington-level event would occur by 2022: https://science.nasa.gov/science-news/science-at-nasa/2014/2...
My 40% is based on that information. I'm gut-extrapolating to the next few decades, with the understanding that large devastating flares occur every few hundred years.
Used by Joyce: “I thunk I told you” (Finnegans Wake); “Have a good old thunk.” (Ulysses)
Does not come, as one may suppose, from a jocular integration from the area of the onomatopeic "thunk", which is 1952. Interesting. Considered in grammarphobia.com )
https://en.wikipedia.org/wiki/Club_of_Rome
But I thought all of that had fallen out of fashion by the early 1980s when oil prices fell and it was discovered that you don't have stable relationships or known parameters for most of this stuff.
Also, the patterns revealed in their models are useful for understanding patterns in nature and human interaction with it.
I know it is always appealing to tell a story with a grand unifying narrative. But sound research must prop it up with empirical evidence. Could there be limits to growth? Probably. But a highly simplistic model not informed by appropriate data or economic understanding is not the way to tell such limits.
that's what an economist would answer. ask a physicist.
for best results, get an economist and a physicist in the same room and ask them both.
Space migration doesn’t change the equation much on Earth unless you start mining and manufacturing off world and importing product, and that is pretty far off.
I agree that decreasing population is desirable from an environmental POV, to the extent that population is more or less directly proportional to consumption. But, capitalism as we know it can't survive it. Here's a good explanation: https://www.axios.com/the-new-threat-to-capitalism-73ff54bd-...
"starting to" is a prerequisite, but a reduction in birth rate doesn't necessarily lead to a population collapse, and you don't seem to present any evidence that this is one of the cases where it does.
Again, I will remind you, the comment says we are "starting to see evidence," of population collapse, not that population collapse is happening or is inevitable. Globally declining birth rates is certainly evidence that it may be happening.
The inputs are the number of people of childbearing age over that time period and the number of births per adult. We know the maximum number of people (since new people don't get born at ages above zero). The number of births per adult tends to change very very slowly and pretty predictably.
A population collapse would be caused by one or both of these things changing dramatically.
There's no evidence of this. Instead there is evidence of a slow decline in population as the birthrate (especially in Africa) slowly decreases.
> What evidence would you consider sufficient, besides globally falling birthrates?
Something that indicates that the current models showing a slow decline are wrong.
Just in case, here is another empirical data comparison for world3 predictions, this time from 2020.
Why? Many civilizations have come and gone through the collapse cycle already. Why do you suspect we're any different? What makes you think the ecosystem can even tolerate 9-10 billion of us?
But we got away with it long enough to a large number of people now believe that this is normal. It isn't. The wake up call will be a very harsh one.
Agreed. Nothing about this is normal. Not the way we live, not the way we work, not the way we take a hot shower every morning. It's highly un-normal. But because we're relative creatures and define the 'normal' by what we experience and not by what has been the normal for hundreds of millennia, we tend to misunderstand the reality of our situation.
The wake up call will be a very harsh one.
(Not to mention that we probably have neither the abilities nor the ecosystem to revert to hunter-gatherer subsistence.)
No, I don't expect a collapse back to the stone-age in the short run. But to every human living in "modern" conditions, a reversion back 100 or even 200 years in terms of comfort and luxury will be quite staggering.
The wake up call will be a very harsh one, nonetheless.
As for a specific carrying capacity for the Earth, it should be obvious how impossible such a number is to give without a lot more detail in the question. But if we were to assume 10B global population, it could be done with a population density roughly equivalent to precolumbian California. This is not to suggest that indigenous californians lived in perfect natural harmony, but rather to illustrate how low the numbers actually are. I suspect there's probably many reasonable (though utterly alien) ways of life where that density could be "sustainable". Equally, I suspect there are many ways of life where those numbers are not "sustainable".
The latest check-up is by Gaya Branderhorst in 2020, https://dash.harvard.edu/handle/1/37364868.
Of course, one has to understand that such a model doesn't show you "on the year 2028 the population is size 16.2931 billion". That is not the point. The point is to show how something grows, or shrinks, and the interrelations of the tracked variables. As x goes higher, y starts to diminish and soon after z goes through the roof, that kind of thing.
The collapse of, for example, industrial output levels might be a form of a Seneca cliff. That is, the growth of the industrial output becomes harder and harder to achieve, while the difficulties compound and actually keep on growing long after the growth of industrial output itself has stagnated or started to drop slightly. This will dramatically increase the inhibitory effect, thus creating a growth curve which starts to slow down and then drops fast ("collapse").
Why dismiss the model? The BAU scenario seems to reflect reality for over 50 years now, so is it not rational to try to understand it?
The Limits to Growth is fundamentally a realization that the world has finite resources. It is not illogical to consider this as a truth. At some point there won't be new resources to obtain, and hence growth in systems based on capturing resources will simply slow down (and perhaps even drop fast, "collapse", because difficulties compound). Circular economy and recycling are good but they cannot expand the available resource pool of e.g. raw materials.
> Meadows, Dennis L., William W. Behrens, Donella H. Meadows, Roger F. Naill, Jørgen Randers, and Erich Zahn. Dynamics of Growth in a Finite World. Cambridge, MA: Wright-Allen Press, 1974.
> Meadows, Donella H., Dennis L. Meadows, Jorgen Randers, and William W. Behrens. The Limits to Growth. New York 102, no. 1972 (1972): 27.
there's lots of people who dismiss this as "doom and gloom". it's worth getting hold of the books and reading through it, and making up your own mind. do you think the modelling assumptions seem reasonable? even if some of the parameters seem difficult to estimate from observed real world data, do you reckon the overall system dynamics behaviour of predicted "overshoot and collapse" seems plausible, even if the timing may be very difficult to predict?
I mean sure, since there is such a thing as an inductive gap in theory, but it seems to me from your statement that you think it to be an insurmountable obstacle in practice as well?
However, seeing as the default likelihood of predicting any future with certainty is zero, a track record of a model of being entirely unable to predict the future at all does very much indicate that such a model will continue to fail, more often than not.
Predicting the future based on what has happened is not reliable, but predicting the future based on models that have predicted the future before should be reliable, if the models themselves are based in reality.
I guess weather/climate models stay somewhat consistent. But they also don’t predict very far forward.
I'm presuming that held out data is used in gradient descent machine learning artificial intelligence, and isn't applicable to systems theory models.
And that other options, including backcasting or parameter adjustment (as was done with different scenarios tested under World3) are.