A hockey stick is the initial part of an S-curve. A point to consider is that all complex systems are functions of multiple variables and more often than not, non-linear. A complete view of the past and the present is not a guarantee of the future. At best, it can be a guide for having cautious behavior.

(It's a day ending in y, so here I go again...)

It depends on the sign of the exponent. Negative exponential growth, as we see in wild animal populations, is not guaranteed to turn into an S-curve. As the passenger pigeon would attest, were any of them left.

Meanwhile, to consider a positive exponent case, there's a real question of what will actually cause the bend in the curve of human population. Will it be getting our collective shit together and slowing down? Or will it be a massive die-off after we've destroyed the ecosystems we depend on for things like air to breathe and water to grow our crops?

> It depends on the sign of the exponent. Negative exponential growth, as we see in wild animal populations, is not guaranteed to turn into an S-curve. As the passenger pigeon would attest, were any of them left.

Sigmoid functions are defined over real input values (not integers). If you were to model the decline in (integer) numbers of passenger pigeons with reals, you would get a sigmoid function were the number at the end approximates, but never reaches zero.

What are you trying to achieve by pointing out one of the ways to construct an incorrect model of the passenger pigeon population?

a) I did not construct the model.

b) Using real numbers to reason about integer base values is not wrong per se. You just need to know how to interpret the result.

Did we "get our shit together" in all the rich countries on the planet, which are barely at replacement levels? Did we hit a massive die-off level by overexploiting our resources?

No. We got rich and having kids was less economically valuable (in fact it becomes a cost in rich societies). The Elon Musks of the world are now more concerned about lack of growth than the opposite.

Who knows if Elon is right or you, but it's not as trivial as it seems to predict whether we will ever hit the carrying capacity of the planet.

"The crisis now unfolding, however, is entirely different to the 1970s in one crucial respect… The 1970s crisis was largely artificial. When all is said and done, the oil shock was nothing more than the emerging OPEC cartel asserting its newfound leverage following the peak of continental US oil production. There was no shortage of oil any more than the three-day-week had been caused by coal shortages. What they did, perhaps, give us a glimpse of was what might happen in the event that our economies depleted our fossil fuel reserves before we had found a more versatile and energy-dense alternative. . . . That system has been on the life-support of quantitative easing and near zero interest rates ever since. Indeed, so perilous a state has the system been in since 2008, it was essential that the people who claim to be our leaders avoid doing anything so foolish as to lockdown the economy or launch an undeclared economic war on one of the world’s biggest commodity exporters . . . And this is why the crisis we are beginning to experience will make the 1970s look like a golden age of peace and tranquility. . . . The sad reality though, is that our leaders – at least within the western empire – have bought into a vision of the future which cannot work without some new and yet-to-be-discovered high-density energy source (which rules out all of the so-called green technologies whose main purpose is to concentrate relatively weak and diffuse energy sources). . . . Even as we struggle to reimagine the 1970s in an attempt to understand the current situation, the only people on Earth today who can even begin to imagine the economic and social horrors that await western populations are the survivors of the 1980s famine in Ethiopia, the hyperinflation in 1990s Zimbabwe, or, ironically, the Russians who survived the collapse of the Soviet Union."

https://consciousnessofsheep.co.uk/2022/07/01/bigger-than-yo...

What in the world does any of that have to do with birth rates and overpopulation, which is the only thing I mentioned? Are you just spamming a link and quote?

Or will it be that people just don't find life worth living and stop having children? E.g. South Korea.

Nearly all developed countries have birth rates below the replacement level. The cluster of reasons for this effect is indeed almost certainly why population levels will level off

And basically none of those reasons are related to the two proposed (“getting our s%%% together” or actual die-offs, both kind of cartoonishly silly). It’s largely the availability of birth control, urbanization, and maybe also old-age safety nets.

The whole world is on the way to doing this (Africa will, too, as they will develop… and, in a note of good news, probably become as economically powerful in the 22nd century as Asia is in the 21st). It’ll lead to a cratering of the working population unless we basically start to eliminate retirement (not desirable!) and enact a ton of pro-natalist policies now (in addition to as much immigration as possible).

A thing people don’t understand is that the biggest resource limit is people. Population decline won’t mean abundance but the exact opposite as the dependency ratio shoots through the roof and will be incredibly stubborn to come down (as to try to reverse it with pro-natalist policies will actually make it significantly worse for a couple decades), especially as willing migrants dry up (yes, I realize how counter-narrative that is, but it’ll happen… in the latter part of this century, Africa will become sick of being the cheap labor source of aging Europe and Asia).

Even with a pessimistic estimate about the rate of progress, fully general AI will be here loooong before population decline decimates the economy, as will good robotics and all the stuff needed to basically put resource gathering and production on autopilot. At that point "on welfare" would easily be the equivalent of living like a millionaire today.

The bigger questions are whether global warming or WW3 will fuck us all before we get there, not to mention the question of whether fully general AI will be its own mega disaster.

Population decline will be a problem in your lifetime. I’ve become disillusioned with the idea that hyper-automation is just around the corner. Observing a Chrysler assembly plant from almost a century ago, vs our current car assembly plants (wiring harnesses still very stubbornly manual), has tempered my expectations of automation progress, as has the slowing of Moore’s Law and the failure of self-driving-cars to materialize in the last few years.

Seeing modern day "best in class" is a great way to become pessimistic about progress, you see the best of now but don't realize it's the worst of "soon". In 8 years you'll reverse course completely based on machining automation, and in 11 we'll have true AGI.

For what it's worth, for me 'getting our shit together' is shorthand for availability of birth control and improving availability of mass education, especially for women. These are the things that have concretely driven reduction in population growth.

I agree about that, but the implication was that we are doing those things to slow or reduce population, not just, you know, because we ought to do them anyway.

Yes, but South Korea is leading the pack. Something unusual since they only industrialized in the 1970s and were poorer than North Korea until the 1980s.

E.G. China.

tang ping

You don't even have the beginnings of any meaningful predictive curve with just a few data points. It's just selective function fitting if there's not a rich data set. For example, you can draw many curves through 2 data points, but you can also draw a straight line. The Our World in Data "Primary vs. planted forest" data that he cites for the "Old Growth Forest Cover" chart has just 2 data points (1990 and 2019).

> You don't even have the beginnings of any meaningful predictive curve with just a few data points. It's just selective function fitting if there's not a rich data set.

Having a rich data set doesn't help. https://twitter.com/SonerCagaptay/status/1389387850551005192

Don't forget the infinite families of higher order polynomials that can have arbitrary shapes beyond the point the observed data ends.

How many physical systems are of those higher order polynomials? Don't most systems have a low number of forcing functions?

> A hockey stick is the initial part of an S-curve.

It's also the initial part to a bell curve.

The downward slope after the peak of this bell curve happens when the population dies off.

Yeah the worst thing is that with the extinction rate, he states that he implicitly sets the background extinction rate to 0 in the year 1000. This is going to bias his 3-point curve fitting even moreso.

The background extinction rate in the absence of humans is probably much higher than 0. New species are also continuously emerging while others are going extinct, so that the total number remains steady.

You are kinda arguing against your point.

Around the year 1000, it's a reasonable guess to assume that emergence of new species and species extinction were roughly in balance, so net extinction rate was indeed around 0.

Today, it's well-established that this net extinction rate is as horrible as is described. A few new species emerging here and there are not enough to compensate for the mess that we are causing on the extinction front, by orders of magnitude.

I might have not expressed myself well in the previous comment, but when I say that "New species are also continuously emerging", it is to prove that the background extinction rate is not zero, not that we don't have a problem.

The curve that he fitted is not the net extinction rate. It's simply the total number of extinctions.

The graph he plots shows the total number of extinctions at year 1000 being 0 or almost 0. This is an assumption. In the absence of humans the extinction rate could be 1,2,10 per year, whatever, it's some small number. The point is that when you are fitting an exponential curve to 3 data points, the resulting curve will be very sensitive to small changes in the value of that point at year 1000. In particular, choosing a value of 0 will force the model towards the steepest possible gradient that the model can allow. i.e. it's biased towards alarmism.

EDIT: Although, when I think about it a little more, a reasonable model would model the extinction rate as an exponential plus a constant value, which would change things. Though a reasonable model probably wouldn't assume an exponential model at all based on 2 data points

Simply looking at the net species over a year doesn't really tell the full story of it.

You can lose megafauna like the American Bison or Steller's sea cow. Smaller fauna like the thylacine are also lost. Such species aren't going to re-emerge in the timescale of humanity. What I named off are just 3 species. If 3 species of ants happen to replace them, that's not really making up the difference. The world has plenty of ants in plenty of species already.

Also please don't drag out the "American Bison isn't extinct!" argument. There were less than a thousand at some point in the 19th century, so all the genetic diversity they had is gone. They've been bred with cattle to the point that the remaining herds are basically all hybrids, despite claims to the contrary. They're also functionally extinct in North America, as all herds are dependent on management at this point.

> Around the year 1000, it's a reasonable guess to assume that emergence of new species and species extinction were roughly in balance

Why?

Yep - "hurr durr I fit a two parameter exponential to three data points OMG guys we should panic now" is just about the weakest argument that has ever been made about any of this stuff.

At the very least, many of the things he's showing would be theoretically expected to follow logistic curves of some form, not pure exponentials.

The author also mentions that their forest cover graph is "old growth", and even claims that this strengthens their point! So if I plant a tree today, or did so 30 years ago, this does not count against their deforestation graph, even though the tree exists, this somehow makes their plot more accurate.

Tree farms are not at all the same environment as old forest growth. I'm all for the critique of S-curves in other responses but this resembles dog-piling.

Or would you say an old meadow full of species of bird, foxes, rabbits and insects, is equivalent to a wheat field?

Planting trees is better than not planting trees, but it's not going to restore the ecosystem that came before it.

Dog piling? I've made one comment on the matter.

I know that old growth is not the same as a freshly planted pine farm. But that's not my point, my point is the author talks about reduced forest cover in aggregate across the land surface of the earth, which is not true, then admits to limiting it to old growth only and hilariously claims that it strengthens his point. It doesn't. When you basically say "forest cover older than 100 years is all that counts" of course the numbers look bad, you're preventing the measure of any repair to the forest cover by definition.