I would recommend reading/watching Steve Keen's critique of Nordhaus's work (e.g., https://www.youtube.com/watch?v=vwwvZ8g5eHE). Steve Keen is the author of Debunking Economics.
Steve Keen is a name I haven't heard in a long time. From what I recall, he is pretty heavily critiqued, not in a "he might be right" sort of way, but more in a "totally misunderstands the basic philosophy underpinning what he critiques and sets up a strawman" kind of way.
The critique is reasonable but it's a straw man -- Nordhaus is already well aware of the critiques he raised and has responded to them.
My source: Nordhaus was my thesis advisor in 2016 and I wrote my thesis according to the same critiques Keen raised in this video, and Nordhaus responded to them... this video was from 2019.
So specifically what is Nordhaus' response to the criticism that a linear (or quadratic) model of gdp vs temperature fitted across space doesn't account for tipping points? Such as, say, if there is a severe scarcity of suitable land for growing food then the effort required to obtain food would likely rise in a very nonlinear fashion? (Not to mention that if that effort is reflected in price it could even show up as a positive in gdp when it's clearly a Very Bad Thing?)
If the model described above is not what he actually did, then what is it he did do?
Feel free to link your thesis if its the most succinct answer...
My thesis modeled the tipping points and extrapolated the damage function via monte carlo. Even in worst case scenarios the models didn't return overall damage functions that provoked the dismal theorem. Fundamental solow growth is too resilient (A = innovation). I didn't submit my thesis for publication so it's just in the university archives. Someday i'd like to revisit it with the latest science and another computational implementation and submit to publication.
To be clear, I'm not saying Keen or Weitzman (Keen here is just parroting the late Weitzman) are wrong -- I'm partial to that intuition hence my thesis work. I'm just pointing out that this speech isn't really engaging with the latest literature on the subject meaningfully.
Can you clarify what TSC means exactly there? in equation 3 it enters a consumption equation in multiplicative form yet in the appendix ""TSC" is the equilibrium response of global mean temperature to a doublin
of atmospheric CO2 concentrations (°C)". Isn't that a confusion of units to multiply a financial quantity by a coefficient that determines temperature?
As such I'm unable to tell (with the time I have available here!) how Nordhaus estimates the severity of any given global temperature change i.e. what data is used to calibrate that relationship
And more crucially to tell whether we're measuring the right thing, as all this seems to be measured in terms of consumption which is usually a financial measure: if (repeating my point above) food takes substantially more effort to produce, or is scarce, in a different climate, then consumption could be shown to increase even though people's wellbeing would decrease?
> Would you mind elaborating? I find him very convincing, but it's not my field.
Not OP but here is an example: Steve is famous in Australia for having predicted the collapse of the Australian Housing market in a significant, and (locally) capitalism-ending way. This has obviously not happened.
Global population stopped accelerating (had an inflection point, or: the "second derivative" went from a positive to a negative value) in the early 1960's. And so, overall population growth has been slowing ever since. It's difficult to say if or when population will reach a new, lower carrying capacity.
It's curious that population growth peaked in most Axis countries before Allied ones in WW2. It would make sense if each country's values were more aligned with others in their faction.
Another inflection point could arguably be the year in which global fertility levels reach less than replacement level. Technically the global population can keep growing after that point, just by people living longer, but if life expectancy starts reverting to the mean then birth rates will have already past the threshold for decreasing global population. Here's what a recent Economist article says:
"The world’s fertility rate, which stood at 3.5 births per woman in the mid-1980s, fell to just 2.4 in 2019. Indeed it is possible, given observed declines in rich-world births during the pandemic, that covid-19 may have pushed the world as a whole within sight of a replacement-level fertility rate, if only temporarily."
Yes, sure. Funny because people like Hans Rosling (mentioned above) predicted that we would reach "peak population" around the end of this century with approx. 11 billion people. This models suggests quite a different outcome. Not marginally but drastically. Interesting to see (interesting was maybe better to have said) where the differences lie but Rosling has already been mentioned above.
Other important state variables in the model are the stocks of "non renewable resources" and "pollution".
From memory I believe one of the ideas in the world model is that over time, as existing stocks of non-renewables are consumed, the remaining stocks of non-renewable resources become more expensive for society to access. E.g. EROI [1] for fossil fuel deposits decreasing. Similarly when mining ore, if the richer ore deposits have all being exhausted, then only lower-grade ore remains, so maybe you need to expend more energy blasting and moving 2x or 3x as much rock as a few decades ago to obtain the same output of metal.
So the idea is that at some point it starts to become more and more expensive -- in terms of the energy input required -- to produce resources that society requires to exist in a steady-state, let alone to continue to fuel growth of the physical economy.
Similarly for pollution -- e.g. for global warming you can regard the atmosphere as a stock where you can store some finite amount of CO_2 pollution before it really starts creating a mess. Once there isn't much stock of cheap CO_2 pollution storage capacity remaining in the atmosphere, you have to start figuring out something else to do, which consumes more energy.
The increasing energy costs of extracting enough non-renewables and dealing with pollution to fuel society leaves less energy for everything else. At some point the energy required for industrial output grows to the extent that there is no longer sufficient energy left for services such as healthcare, education, etc. Therefore the quality of healthcare and education falls off. That has consequences for the human population.
You're right on. People often think peak oil means no more oil. Really it just means it's no longer energy positive investment.
[1] The EROI for fossil fuels has decreased as the availability of oil, coal, gas has reduced and the cost of production increased. Fracking for oil or gas (as has been done in Taranaki for years) is expensive and polluting. Extracting oil from the tar sands in northern Canada is a similarly destructive process. So, what was an EROI of 100:1 last century is now sometimes little more than 10:1.
Yes. Checking this via various sources online shows that the predictions are that capital intensity will reach 50% of all investment by 2020, at which point the collapse begins.
On the other hand, population levels reducing (via education and stability) will reduce the amount of resources globally needed, and the loss of workforce can be compensated by technology. That can lead us to a scenario that's perfectly fine despite a high cost of resources.
There are 2 scenarios in the original Limits to Growth that encapsulate this:
1. The "comprehensive technology" scenario in which population stabilizes, food production increases to keep pace, pollution eventually drops to essentially zero, and industrial output actually decreases as a result of increased efficiency.
2. The "stabilized world" scenario, where population, industrial output, and food output all stabilize quickly, and pollution also eventually drops to 0.
The difference between these 2 scenarios is essentially that in the latter, technology does not progress fast enough to save us, but we are able to put the brakes on and save ourself; while, in the former, increases in efficiency due to technology are what allows us to stave off collapse.
Is it possible than when civilization collapses we can only really realize it in hindsight? Kind of like how the only way to really know we went through a recession or depression is after the fact or at some point during it? Maybe we are already living in post-collapse.
Compared to 2015? Yeah our technology is better, our shared knowledge is increasing, population is increasing, etc. In a collapse, I’d expect to see near 0 investment in new technology with more energy going into basic survival and trying to protect a declining population.
If you think we’re in a setback, decline, etc., maybe, but when I think collapse, I think a “Guns, Germs & Steel” / Easter Island type event.
What if we measured collapse as "proportion of population being left behind"?
How have education outcomes changed past 18 months? What about specifically to the 95th percentile most/least deprived?
How have health outcomes changed past 18 months? What about the quantiles?
How have financial plans been affected past 18 months? How much worse off are those who already weren't that well off?
How have climate change outcomes changed past 18 months? Will the recent climate action drive meaningful outcomes or is it another power/cash-grab with social utility you gotta search for?
What will be the cumulative effect of all this on people's willingness to introduce human life to the planet?
Human reproductive potential has been steadily declining for something like a century. Have the past 18 months been more of the usual or has the gradient been steeper? How significant of a fertility rate decline can the economic system tolerate be
Basically what I'm trying to say is: as the mean changes, how are the tail ends affected? Is the tail end activity contributing to some kind of feedback loop?
I think we’ve collapsed. A lot of peoples lives are an endless hell which I see no escape from, they just trudge along because they have some hope but haven’t fully realized how screwed they are. Many people have chosen to stop working all together. Eventually they may decide to all together stop obeying laws. A Louis Vuitton store in San Francisco was robbed blind recently.
For us elites life is still somewhat good, but the dominos are falling and we just haven’t been hit yet.
> What if we measured collapse as "proportion of population being left behind"?
Well then it clearly isn't.
Outside rich Western countries life is - on average - getting better. For every disaster like Syria there is are multiple quiet successes across the poorer parts of the world where millions of people get measurably better by 5 or 10%.
Eg, in Nigeria, where between 2009 and 2019 average life expectancy increased by over 4 years.
To quote William Gibson, “The future is already here – it's just not evenly distributed."
In other words, expect to see some things getting better while other things we've long taken for granted get worse. It all gets much patchier, the interdependencies more fragile, more brittle, until, quite suddenly, collapse is upon us. So at the same time as we're getting better network connectivity, the electricity supply is more erratic, prone to unexpected failures. Just as we're getting better vaccines, postal service is coming apart. And so on. And it's different kinds of patchiness in different parts of the globe, and the more tightly we interdepend different geographies, the more sudden and weirdly perplexing the failure modes manifest. Container shipping, anyone?
It's a process, not a single inflexion point. Only somewhere deep in the future will historians put a stick in the ground and say, "There. That was where the collapse was undeniably evident."
That could be a consequence of absurdly inflated sugar intake (without adequate fiber) causing Metabolic Syndrome that causes a host of different acute, often enough fatal ills.
But persuading Americans to ditch sugar and eat more fat will be a hard sell after so much propaganda against the has spilled.
Interestingly life expectancy in the U.K. is also down, and it may be no coincidence that both countries have increasingly high levels of inequality post crisis.
Of course historians from 3000 AD could say that western civilization collapsed on the day of the Hiroshima bomb, or 9/11, or the year of Covid, or who knows when. Anything that fits their political goals would do.
One (of the many) problems with predicting a societal collapse is the word itself, "collapse", being incredibly vague. What would define a collapse? For most it seems to conjure up visions of apocalyptic disasters. But it could potentially be a long, drawn out change to the trajectories of many metrics surrounding human population and economic activity. Who knows? I doubt we will even be able to define what a "collapse" is, let alone predict when that collapse might occur using modeling techniques.
Not sure I understand the reason this kind of model keeps getting spawned every few years. Idealized models with no relevance to empirical observations are nowhere near predicting civilization collapse. They can't even explain the observed past trajectories.
the references to have a read through are not science fiction, but are system modelling studies done in the 70s:
> 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'm reading Donella Meadows' Thinking in Systems right now which I think is a good overview of this line of reasoning. Of course models are idealized, but they're also one of the best ways to understand complex systems. The human brain does something very similar in forming intuitions about the world, but we should recognize that in order to make a better model we will have to make one in silico. Another interesting approach is agent-based modeling, which explores how the decisions of agents with limited information can create emergent patterns.
Ok so assuming you had a system that you could give it a bunch of inputs and it would predict what the results from those would be 10 years out, and it was correct 60% of the time from past observations, and you had run it on thousands of simulations (this is obviously a hypothetical) is it then your contention that if you gave it inputs from our current inputs and had it predict results ten years from now that those predictions would not have a 60% chance of being correct?
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?
It's obvious enough. Conditions change. Systems are dynamic. A model of human society that "works" for the next 10 years may not work for the subsequent 10 years.
I'm guessing you're using an analog to "past performance doesn't predict future performance" which is true.
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.
how did everyone’s model of 2019-2021 pan out on any given metric? Even if they successfully predicted that same metric correctly for the last 100 years.
I guess weather/climate models stay somewhat consistent. But they also don’t predict very far forward.
Because the data keeps matching their Business as Usual model. I think there's more recent research, but here's a paper from 2014, showing 40 years of reasonable fit: http://sustainable.unimelb.edu.au/sites/default/files/docs/M.... If we keep matching their model, we'll soon see dramatic population declines.
Also, the patterns revealed in their models are useful for understanding patterns in nature and human interaction with it.
Just looking at Figure 1 on page 8 of the paper you mentioned, it can go either way because we haven't seen a reversal in any of the trends. That is hardly a prediction. For example, if one looks at the "Services per capita", is there any sign that it will meet an inflection point in the next few years?
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.
"Could there be limits to growth?" Yes 100% (you cannot extract indefinitely more and more every year from finite resources), the debate is simply when we'll peak for a given ressource (20 years, 100 years, 1 million years) and the size of such an impact on the economy.
There have to be limits to growth, but we won’t know where they are except in retrospect. We also may never hit them due to fertility decline which occurs in all wealthy societies. Fertility decline plus efficiency increase could cause consumption of some resources to fall.
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.
Slowing birthrates is very far from a population collapse. It's also (to generalise vastly) desirable - slower population growth is desirable environmentally.
This is why I said "starting to." You did notice those two very important words, didn't you? Because this is how it starts.
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-...
> This is why I said "starting to." You did notice those two very important words, didn't you? Because this is how it starts.
"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.
What evidence would you consider sufficient, besides globally falling birthrates?
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.
Well population dynamics are pretty predictable for the next ~40 years or so.
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.
It's worth noting that world3 model is fairly sensitive to initial conditions and small perturbations can yield population predictions exceeding 20 billion or under 1 billion [0]. It's pretty unclear whether the patterns are actually useful or actually "natural" rather than artificial. For instance, virtually all scenarios in world3 end up in a peak->collapse, but it strains credulity to imagine that similarly applies in the real world.
> For instance, virtually all scenarios in world3 end up in a peak->collapse, but it strains credulity to imagine that similarly applies in the real world.
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?
The eocsystem we were born into as humanity would not sustain even a small fraction of the humans alive today. We modify the ecosystem until it will sustain us (or 'just us', for that matter).
What makes you think we can continue to do that? Even if we can, what makes you think we can do it sustainably? And if we can do it sustainably, what makes you think we will? History doesn't really provide any encouragement here.
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.
Just to be clear, if by "normal," you're referring to the way humans existed for 95% of their existence, which was as small bands of hunter gatherers, that very clearly implies an advanced state of collapse. Even if some of the worst case scenarios for collapse come true, that's a long ways off. For one thing, it would probably imply a significantly reduced population (probably no more than 10-20% of current population levels) before nomadic hunter gatherer groups becomes an efficient way to live.
That was just an observation with regards to what we "modern" humans consider to be "normal", not a comment on how far down the next collapse will bring us.
(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.
If you pick any particular definition of "collapse", very few will actually meet it (let alone on a timescale of mere years or decades). There's quite a lot of literature on this subject already (e.g. Questioning Collapse), but there's also tens of thousands of years of human history apparently lacking records of anything that could be called a collapse.
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".
Right, because all these models are just that: models, and very simple ones at that. They encode a few functions, often linear, when the thing they model are enormously complex and dynamic. Humans generally fail to grasp the non-linear and the dynamic.
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.
> high standards of living + high taxes and costs + high retirement costs
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.
You're not taking into account technological and industrial innovation. Presumably there will be new ideas iterated upon that get us closer to universal abundance.
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.
resources are finite and technological innovation is finite, too. thermodynamics gives us very precise upper limits to efficiency increases and to the surprise of no one, low hanging fruit are all picked.
a single example: a 100 years ago the efficiency of ICEs was less than 50% of today's. we're left with maybe 2x until physics doesn't allow us any further improvements.
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.
The hard variable is paradigm-shifts. We see things like quantum computers now, which seem boring at the moment, but the sorts of problems they'll be able to handle are staggering to imagine.
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.
> 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...
There are several potential paradigm shifts which this doesn't address.
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.
Medieval people where aware that you could send messages faster than a horse.
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.
> the problem is, thermodynamics is so generic that it's hard to imagine how to sidestep it - and people do try all the time.
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.
You're making the same mistake all the star eyed futurists make, which is to not realize that in reality, all exponential curves are just early/mid stage sigmoidal curves. You can paradigm shift all you want, that's not going to make infinite progression a thing.
You're making the same mistake all star eyed futurists-skeptics make, which is to not realize that in reality, new sigmoidal curves are started all over the place.
It's just a matter of time and survival. How long? I don't know. Probably long.
There is a finite set of sigmoidal curves that can accelerate/plateau. If you add the "progress" from every curve in the set, that also forms a sigmoidal curve (via a transformation of the central limit theorem) with a plateau that is inescapable. You can't out paradigm shift the nature of reality.
Indeed. Eventually the planet will run out of CO2 and life on Earth will almost completely disappear. Eventually plate tectonics will stop as well due to the core of the planet cooling. Eventually the Sun will go red giant and the Earth will really die then. Eventually we'll reach the heat death of the universe.
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.
Kind of unrelated but if you're interested in African agriculture you should look into Seeing Like a State. The book argues mechanized farms aren't necessarily the highest form of farming for maximum sustainable yield in many places (like many regions in Africa) and has many many hard to notice downsides. A lot of the pressure to consolidate and mechanize has to do with legibility for taxation purposes compared to true yield maximization
Society is so incredibly dependent on technology that is not EMP resistant and if a solar flare knocks out most of our electronics the bottom is going to fall out. No phones or internet to figure out what's going on, no cars since the onboard electronics are needed- same with trucks, trains etc. Can't go to the grocery store and buy food with your debit card, can't get cash from the bank, grocery store isn't going to get shipments anymore etc.
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
I have read that the dangers of EMP's are greatly overstated and they could damage stuff, but mostly the power grid, since you need long lines to induce sufficient power for it to matter.
Not GP but it's a cascade failure mode with theoretically no upper bound in how much chaos it could cause. A toilet paper shortage caused millions to lose their goddamn minds, what do you think having no refrigeration on a world scale for even a week would do? A CME could potentially fry enough equipment that we would be left in in the dark and unable to repair for months, just due to availability of parts. I believe those estimates are at current production rates, too. If the supply chain and global comms are compromised, it's even harder.
It's definitely at the sweet spot of "terrifying" and "completely plausible."
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.
('thunk': «from an 1876 glossary of words in the mid-Yorkshire dialect in Britain», presumably jocular.
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 )
I remember the Club of Rome was the first to do these models, assuming peak oil and the collapse of western civilization based on resource constraints. They would have these coupled differential equations, similar to predator-prey, calculating cost of extracting resources and the resulting declines in food production and thus population.
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.
Exactly. You can have very sophisticated, non-linear, dynamic models developed over many years by brilliant people, then still see the models fail miserably.
During the 1970s the Club of Rome made "The Limits to Growth" with the World3 model and, whatever it predicts, some scenarios like the Business As Usual (BAU) seems to have tracked quite well for ca. 50 years already.
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.
So an elementary model which cannot possibly hope to model all the real world variables is gonna predict the future? No no, this is too much but it's a cute toy, to play with models.
The predictions from the model all match up in line with the parts of the model predicting an increase in various metrics, but the crux of the model, the inflection point and collapse, all have yet to occur yet. In other words, there would be nothing to prove that this model is any better or worse than a model that predicts these metrics continue to increase indefinitely.
The fact that there is good agreement between the model and real world data extending 40 years past its creation should, at least, raise your prior probability that the model is correct enough to be useful. If not, you're just being irrational.
To paraphrase Brahms when he first heard the Dvořák cello concerto: if I had known that it was possible to write a package like this, I would have tried it as well!
I love this. It would be interesting to pair it with a decent climate model, though.
As said above, no models are correct, some models are useful. I see the statement as akin (in some ways) to lies, damn lies and statistics, or the spherical cow.
The models cannot predict the future. Too many charlatans have attempted to tell the public that they can, but they can't, and as a result people look for models that can, criteria by which they can trust models based on the credentials of their creators or the granularity of the source data, even reasonable implementation of the source data, but of course, no model can.
But a model can teach you something about the mechanisms behind the interplay between different systems. It can tell you something general about the effects of certain situations. A good example of this can be seen in Lorenz's weather prediction models leading to the formal discipline of chaos theory. Often, algorithmic interaction between different values in models can lead to a discovery of a previously unknown mechanism by which something about the world can be gleaned, even if the model itself is useless at accurately predicting the future.
But you're right, a model can predict nothing, and people need to bear that in mind, because pop science has people convinced that they should live their lives as if existing models can and do predict the future when in fact they do not.
Reminds me of an old Apple II MECC program from the early 80s called Limits. The user could "tune" various portions of the model and run projections as to when the world would reach its "limits" and collapse. Seems people have dug these sorts of automatic speculations for some time.
It may be instructive to compare individual health, where we have great experience with decline and collapse.
Consider a physical activity that imposes a strain resulting in damage to tissue (muscle, tendon, cartilage, what-have-you) that heals fast enough not to accumulate. As you age, your rate of healing declines gradually. At exactly the point where rate of healing matches the rate of damage, you start into a sharp decline all out of proportion to any apparent, experienced event, as damage begins to accumulate at an unceasing rate.
All contact-lens users hit such a point where their eyes seem "suddenly" to begin a rapid downslide if they do not abandon contacts.
Many systems operating at global level have this character.
> the loss of cultural identity and of socioeconomic complexity, the downfall of government, and the rise of violence
And it isn’t usually a slow process:
> Societal collapse is generally quick
So for Western civilization or the US to truly collapse it means a complete loss of cultural identity, destruction of the economy, no government and tons of violence.
Even war torn countries rarely collapse because even if the government is removed, violence spikes and the economy stops working the people can still maintain a sense of common shared culture and identity and avoid collapse. I guess it becomes more of a rebirth or evolution at that point.
I think a lot of people see 1 sign of collapse and think it’s a collapse, but it’s actually just a decline or an oscillation.
Collapse includes decline but decline doesn't necessarily lead to collapse. That said, collapse is really just decline that happened too fast. Decline appears to be caused by a handful of factors. In the event that too many factors are in play at once collapse becomes inevitable.
You could say the the US / Western civilization is the rebirth of the Roman Empire (Rome 2.0). If you look at the historical accounting of the [1] Roman collapse it is frighteningly similar to the issues US is facing at the moment.
However, it is possible that societies are doomed to the 4 stages of [2] Strauss-Howe generational theory of cyclical repetitions with an inability to ever break free of it.
this model is very sensitive to certain inputs if smidged a little bit yield vastly different projections. Models are more convincing when they are robust to that sort of thing. For instance go here: http://bit-player.org/extras/limits/ltg.html and try increasing the "output consumed (fraction)" input a little bit.
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[ 3.7 ms ] story [ 159 ms ] threadFor reference, the field of looking at future civilization direction w/r/t climate change is called "Integrated Assessment Models," and DICE (from Nordhaus) is one of the most used and also open source https://williamnordhaus.com/dicerice-models . Here's the UNFCCC page on them. https://unfccc.int/topics/mitigation/workstreams/response-me... .
All models are wrong, some models are useful.
My source: Nordhaus was my thesis advisor in 2016 and I wrote my thesis according to the same critiques Keen raised in this video, and Nordhaus responded to them... this video was from 2019.
If the model described above is not what he actually did, then what is it he did do?
Feel free to link your thesis if its the most succinct answer...
My thesis modeled the tipping points and extrapolated the damage function via monte carlo. Even in worst case scenarios the models didn't return overall damage functions that provoked the dismal theorem. Fundamental solow growth is too resilient (A = innovation). I didn't submit my thesis for publication so it's just in the university archives. Someday i'd like to revisit it with the latest science and another computational implementation and submit to publication.
To be clear, I'm not saying Keen or Weitzman (Keen here is just parroting the late Weitzman) are wrong -- I'm partial to that intuition hence my thesis work. I'm just pointing out that this speech isn't really engaging with the latest literature on the subject meaningfully.
As such I'm unable to tell (with the time I have available here!) how Nordhaus estimates the severity of any given global temperature change i.e. what data is used to calibrate that relationship
And more crucially to tell whether we're measuring the right thing, as all this seems to be measured in terms of consumption which is usually a financial measure: if (repeating my point above) food takes substantially more effort to produce, or is scarce, in a different climate, then consumption could be shown to increase even though people's wellbeing would decrease?
Not OP but here is an example: Steve is famous in Australia for having predicted the collapse of the Australian Housing market in a significant, and (locally) capitalism-ending way. This has obviously not happened.
Interesting package. Neat work
It's curious that population growth peaked in most Axis countries before Allied ones in WW2. It would make sense if each country's values were more aligned with others in their faction.
The models seems to predict differently..
https://fs.blog/hans-rosling-population-growth/
"The world’s fertility rate, which stood at 3.5 births per woman in the mid-1980s, fell to just 2.4 in 2019. Indeed it is possible, given observed declines in rich-world births during the pandemic, that covid-19 may have pushed the world as a whole within sight of a replacement-level fertility rate, if only temporarily."
https://www.economist.com/finance-and-economics/2021/12/11/w...
It's where I first heard the term "peak child" or "peak baby" to describe this.
Can you extrapolate on what you mean by this?
From memory I believe one of the ideas in the world model is that over time, as existing stocks of non-renewables are consumed, the remaining stocks of non-renewable resources become more expensive for society to access. E.g. EROI [1] for fossil fuel deposits decreasing. Similarly when mining ore, if the richer ore deposits have all being exhausted, then only lower-grade ore remains, so maybe you need to expend more energy blasting and moving 2x or 3x as much rock as a few decades ago to obtain the same output of metal.
So the idea is that at some point it starts to become more and more expensive -- in terms of the energy input required -- to produce resources that society requires to exist in a steady-state, let alone to continue to fuel growth of the physical economy.
Similarly for pollution -- e.g. for global warming you can regard the atmosphere as a stock where you can store some finite amount of CO_2 pollution before it really starts creating a mess. Once there isn't much stock of cheap CO_2 pollution storage capacity remaining in the atmosphere, you have to start figuring out something else to do, which consumes more energy.
The increasing energy costs of extracting enough non-renewables and dealing with pollution to fuel society leaves less energy for everything else. At some point the energy required for industrial output grows to the extent that there is no longer sufficient energy left for services such as healthcare, education, etc. Therefore the quality of healthcare and education falls off. That has consequences for the human population.
[1] https://en.wikipedia.org/wiki/Energy_return_on_investment
[1] The EROI for fossil fuels has decreased as the availability of oil, coal, gas has reduced and the cost of production increased. Fracking for oil or gas (as has been done in Taranaki for years) is expensive and polluting. Extracting oil from the tar sands in northern Canada is a similarly destructive process. So, what was an EROI of 100:1 last century is now sometimes little more than 10:1.
[1] https://www.newsroom.co.nz/why-hydrogen-is-not-a-cure-for-em...
https://sustainable.unimelb.edu.au/__data/assets/pdf_file/00...
1. The "comprehensive technology" scenario in which population stabilizes, food production increases to keep pace, pollution eventually drops to essentially zero, and industrial output actually decreases as a result of increased efficiency.
2. The "stabilized world" scenario, where population, industrial output, and food output all stabilize quickly, and pollution also eventually drops to 0.
The difference between these 2 scenarios is essentially that in the latter, technology does not progress fast enough to save us, but we are able to put the brakes on and save ourself; while, in the former, increases in efficiency due to technology are what allows us to stave off collapse.
https://www.youtube.com/watch?v=kVOTPAxrrP4
https://news.ycombinator.com/item?id=29525410
But maybe a point of no return would be harder to detect. Like health is improving but resources are dropping to unrecoverable levels.
If you think we’re in a setback, decline, etc., maybe, but when I think collapse, I think a “Guns, Germs & Steel” / Easter Island type event.
A much longer time frame will be required to determine if life is improving over time for people or not. Possibly on the scale of generations.
How have education outcomes changed past 18 months? What about specifically to the 95th percentile most/least deprived?
How have health outcomes changed past 18 months? What about the quantiles?
How have financial plans been affected past 18 months? How much worse off are those who already weren't that well off?
How have climate change outcomes changed past 18 months? Will the recent climate action drive meaningful outcomes or is it another power/cash-grab with social utility you gotta search for?
What will be the cumulative effect of all this on people's willingness to introduce human life to the planet?
Human reproductive potential has been steadily declining for something like a century. Have the past 18 months been more of the usual or has the gradient been steeper? How significant of a fertility rate decline can the economic system tolerate be
Basically what I'm trying to say is: as the mean changes, how are the tail ends affected? Is the tail end activity contributing to some kind of feedback loop?
For us elites life is still somewhat good, but the dominos are falling and we just haven’t been hit yet.
Well then it clearly isn't.
Outside rich Western countries life is - on average - getting better. For every disaster like Syria there is are multiple quiet successes across the poorer parts of the world where millions of people get measurably better by 5 or 10%.
Eg, in Nigeria, where between 2009 and 2019 average life expectancy increased by over 4 years.
In other words, expect to see some things getting better while other things we've long taken for granted get worse. It all gets much patchier, the interdependencies more fragile, more brittle, until, quite suddenly, collapse is upon us. So at the same time as we're getting better network connectivity, the electricity supply is more erratic, prone to unexpected failures. Just as we're getting better vaccines, postal service is coming apart. And so on. And it's different kinds of patchiness in different parts of the globe, and the more tightly we interdepend different geographies, the more sudden and weirdly perplexing the failure modes manifest. Container shipping, anyone?
It's a process, not a single inflexion point. Only somewhere deep in the future will historians put a stick in the ground and say, "There. That was where the collapse was undeniably evident."
https://www.letstalkthis.com/collapse/
That could be a consequence of absurdly inflated sugar intake (without adequate fiber) causing Metabolic Syndrome that causes a host of different acute, often enough fatal ills.
But persuading Americans to ditch sugar and eat more fat will be a hard sell after so much propaganda against the has spilled.
> 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.
https://people.duke.edu/~rnau/three.htm
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.
[0] https://doi.org/10.1287/mnsc.44.6.820
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 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.
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.
Do you have a more specific or substantive criticism of this work? Otherwise, I'd say it's essentially proven itself.
I love this. It would be interesting to pair it with a decent climate model, though.
An abstract model can predict nothing, especially when the system is not fully observable, discrete, fully deterministic.
Abstract modeling is the modern age astrology.
The models cannot predict the future. Too many charlatans have attempted to tell the public that they can, but they can't, and as a result people look for models that can, criteria by which they can trust models based on the credentials of their creators or the granularity of the source data, even reasonable implementation of the source data, but of course, no model can.
But a model can teach you something about the mechanisms behind the interplay between different systems. It can tell you something general about the effects of certain situations. A good example of this can be seen in Lorenz's weather prediction models leading to the formal discipline of chaos theory. Often, algorithmic interaction between different values in models can lead to a discovery of a previously unknown mechanism by which something about the world can be gleaned, even if the model itself is useless at accurately predicting the future.
But you're right, a model can predict nothing, and people need to bear that in mind, because pop science has people convinced that they should live their lives as if existing models can and do predict the future when in fact they do not.
Consider a physical activity that imposes a strain resulting in damage to tissue (muscle, tendon, cartilage, what-have-you) that heals fast enough not to accumulate. As you age, your rate of healing declines gradually. At exactly the point where rate of healing matches the rate of damage, you start into a sharp decline all out of proportion to any apparent, experienced event, as damage begins to accumulate at an unceasing rate.
All contact-lens users hit such a point where their eyes seem "suddenly" to begin a rapid downslide if they do not abandon contacts.
Many systems operating at global level have this character.
From Wikipedia: https://en.m.wikipedia.org/wiki/Societal_collapse
Here’s the definition:
> the loss of cultural identity and of socioeconomic complexity, the downfall of government, and the rise of violence
And it isn’t usually a slow process:
> Societal collapse is generally quick
So for Western civilization or the US to truly collapse it means a complete loss of cultural identity, destruction of the economy, no government and tons of violence.
Even war torn countries rarely collapse because even if the government is removed, violence spikes and the economy stops working the people can still maintain a sense of common shared culture and identity and avoid collapse. I guess it becomes more of a rebirth or evolution at that point.
I think a lot of people see 1 sign of collapse and think it’s a collapse, but it’s actually just a decline or an oscillation.
Collapse includes decline but decline doesn't necessarily lead to collapse. That said, collapse is really just decline that happened too fast. Decline appears to be caused by a handful of factors. In the event that too many factors are in play at once collapse becomes inevitable.
You could say the the US / Western civilization is the rebirth of the Roman Empire (Rome 2.0). If you look at the historical accounting of the [1] Roman collapse it is frighteningly similar to the issues US is facing at the moment.
However, it is possible that societies are doomed to the 4 stages of [2] Strauss-Howe generational theory of cyclical repetitions with an inability to ever break free of it.
[1] https://en.m.wikipedia.org/wiki/Societal_collapse#Demographi... [2] https://en.m.wikipedia.org/wiki/Strauss%E2%80%93Howe_generat...