For example, the World Bank: http://data.worldbank.org/data-catalog/population-projection...
If you look for dinosaurs, the WB also have a 1984 report on topic: http://documents.worldbank.org/curated/en/496471468156899142... (see p. 186, "Population data supplement")
The UN, IMF, and most national agencies also release their numbers.
In general, world GDP growth — and its correlates, like HDI — is stable enough to predict population growth. As a country gets richer, fertility falls: women get careers, jobs require more education for children, people start to rely on savings, instead of family. The aggregate numbers are smooth and predictable. At least, for a reasonable time horizon.
But you need to fine-tune the model at the right aggregation level. For example, the US, EU, Japan have similar GDP levels, but fertility in the US remains high. Census data helps settle down these issues.
Edit: Forgot to thank my parent comment for finding the data in the first place!
http://blogs.worldbank.org/futuredevelopment/rapid-slowdown-...
You can see that the growth is rushing towards zero and almost crosses it in 2100, giving a maximum sometime around 2115. But I wouldn't really count on any projection's accuracy that far into the future: what really sticks out is how the historical growth is extremely jagged, driven by crises and revolutions, then becomes ridiculously smooth as soon as it turns into a projection. It just screams out "this is a very rough approximation and probably wrong".
He also just assumes some naive correlations based on some graphs, without doing any rudimentary statistics (e.g. chi squared to check if the correlations are even notable), and then plugs the numbers in and see's what he comes out with.
Instead, he should base his model on data from say 2000, and then predict the population in 2015, and then if that's correct, he might be able to say something about 2065 with any degree of certainty.
That he disagrees with other predictions suggests his model is wrong, but it's difficult to say how.
- Birthrates are assumed to fall linearly all the way to zero, despite an abundance of reasons why that's obviously not likely to be the case
- If I'm reading it correctly, countries' birth rate declines are estimated as a discrete property of arbitrary HDI labels rather than a function of actual HDI score. Which in practice means that minor threshold differences decide whether birthrates in a country to fall sharply across one decade and less sharply in another
- Small islands are given equal weight to China and India in gauging an HDI-bracket's average birth rate
- The HDI brackets aren't even copied correctly, and thus many ultra wealthy territories like Bermuda and Gibraltar are placed in the "low HDI" bracket. That probably means the model massively underestimates the YoY decline in birthrates in low development countries (which I suppose at least works in the opposite direction to incorrect assumptions made about birthrates dropping to zero)
- There's really no justification at all for projecting a death rate that varies between ~1 and ~15 per 1000 as a uniform 8 per 1000, especially not when data on population age distributions and life expectancies exists. (The only saving grace is that it isn't that far from the figure for India and China which have a disproportionate effect on the model)
Uh.... This seems incorrect. Sure we can extrapolate the declining birthrate all the way down to zero, but realistically it will level out somewhere since humans will never stop producing more humans. Granted it might be a lower birthrate, but never 0.
Estimates that the recent declines in birth rate will continue until 0 annual births, once the birth rate stops the death rate continues at pace, and kills everyone eventually.
Flawed in many ways, but that is the biggest mistake. A good example would be the temperature has dropped 20 degrees in the last month at this rate we will reach absolute 0 in around 2 years.
I spent a chunk of my life adjacent to bio/med research and my conclusion is radical life extension by purely biological means will probably remain unfeasible. Genetically, we're millions of years worth of horribly interdependent spaghetti code, there is no fixing this mess. So - barring the option to upload yourself to silicon - death won't be obsolete by 2065.
However we might see some very, very moderate increases in life expectancy across the board, even in comparatively poor nations, as long as they're not living in abject poverty. This would be cause for concern, but data from industrialized nations suggest a major regression in births once a population becomes (somewhat) wealthy and healthy.
The desire to procreate boundlessly may very well be a deep-seated instinct triggered by living in precarious environments. If dying slows down, it's because of improved living standards and medical care, the same things that stop over-procreation.
It seems to me that in order to control Earth's population, we need to address poverty, which incidentally would solve a huge slew of other humanitarian and ecological problems.
Second, one doesn't have to eliminate biological death entirely to muck up those forecasts. We know from super-centenarians that those who are lucky enough to not suffer any life threatening conditions nevertheless kick the bucket around age 120. Even if that's not fixed by 2065, it's almost double the average life expectancy and that is not factored at all into the OP's calculations.
Third, birthrates are currently constrained by menopause in women. Most women don't have more than a few children in the developed world because they are biologically incapable of having more. And although men have the capability to have "2nd families" (with another woman later in life after their previous children are grown), women do not. Defeating/controlling menopause is therefore more likely to result in either larger families, women choosing to have a second family at a later stage in life, or women who would have otherwise missed their chance having a family at all. Again, fertility advances are not factored into the OP's calculations.
Thus although I could argue that biological immortality is not "unfeasible", I don't need to. The OP has failed to factor in reasons why the death rate will go down and the birth rate will go up, making his charts too conservative.
To me, it also means that the "upload to silicon" stage is unlikely, because it probably requires understanding and reimplementing (possibly bug-for-bug, in some places) the original, for, uh, carbon compatibility. (And if we really understood it that well, we'd probably just fix the original...)
Would have been interesting to look at the impact on the high HDI countries of mass invasion and demographic replacement. Many of those countries won't be in the "very high" category much longer. That will have the obvious impact on birth rates etc. Ditto long term trends in income inequality, in that population stats meant something when populations were more equal, but the average of oil and water isn't a salad dressing.
Maybe. Or maybe we're so wealthy and have so few kids that the health care industry is draining off the excess?
In either case, I think it's hard to make such generalizations about a group that includes both the US and countries that have single payer health care.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3192186/
"A common objection against starting a large-scale biomedical war on aging is the fear of catastrophic population consequences (overpopulation). This fear is only exacerbated by the fact that no detailed demographic projections for radical life extension scenario have been conducted so far. This study explores different demographic scenarios and population projections, in order to clarify what could be the demographic consequences of a successful biomedical war on aging. A general conclusion of this study is that population changes are surprisingly slow in their response to a dramatic life extension. For example, we applied the cohort-component method of population projections to 2005 Swedish population for several scenarios of life extension and a fertility schedule observed in 2005. Even for very long 100-year projection horizon, with the most radical life extension scenario (assuming no aging at all after age 60), the total population increases by 22% only (from 9.1 to 11.0 million). Moreover, if some members of society reject to use new anti-aging technologies for some religious or any other reasons (inconvenience, non-compliance, fear of side effects, costs, etc.), then the total population size may even decrease over time. Thus, even in the case of the most radical life extension scenario, population growth could be relatively slow and may not necessarily lead to overpopulation. Therefore, the real concerns should be placed not on the threat of catastrophic population consequences (overpopulation), but rather on such potential obstacles to a success of biomedical war on aging, as scientific, organizational, and financial limitations."
Why the situation tragic? The universe does not care the sea levels or temperatures are different from what they were in 1700, just as the universe does not lament the great oxidation event which wiped out most of the species inhabiting the planet at the time.
In fact I'd argue that most humans are elated that cyanobacteria 'destroyed' the planet.
You could argue that we are already past the carring capacity of Earth as of today, and the reason we do not see a massive dieoff today is that we are, so to speak, burning our runaway instead of generating (enough) revenue.
With regards with your "Why the situation tragic?" comment... I also felt a great relief when I realized that we (as global society) will not wipe life on earth, and probably will not even wipe human life on earth with our colective stupidity.
However, a drastic reduction in population is due during the next 100 years or so, and most of it wont be voluntary. A lot of needless suffering is going to happen, and no, it will not matter much in the grand scheme of things. Do you really need to be so smug about it, though?
This nonsense about "the universe doesn't care about our climate" has got to stop. No, it doesn't, but humans also don't care about what the universe cares about.
If you want to take such a large view that the fate of people doesn't matter, then go for it, but don't be puzzled when you end up in a tiny minority by doing so.
The rest of us would be elated if you grew a sense of empathy for your fellow humans.
See: http://climate.nasa.gov/interactives/climate-time-machine
not sure if there's anything more to say.
Limits to Growth, whether you agree with their conclusions or not, is an actual model.
The google docs above is one guy fiting a curve to a bunch of demographic statistics. There is no real causality there, no attempt to make an interpretation of the numbers. If he would have done so, he would - as others have already pointed out - reached the conclusion that: "Since birth rates decrease when people's lives improve, Progress will make our life so fulfilling that we will stop having children altogether. Then we will live happily ever after until we all die of old age."
Automation might make manual labor a thing of the past. We might not have enough jobs or natural resources to support a growing population.
Sadly I feel like studies like this don't take into consideration what a ww3 might do on the world's population long term. We are in an unprecedented time of peace which might not last to 2065.
It would be interesting to analyze food production capability at various levels of petroleum production and then analyze the probability of those various levels of petroleum production. The days of powering your oxen with some acres of hay are long gone, takes quite a few calories of fossil fuels to generate each calorie of food.
Fossil water is another interesting concept. The east of the USA has more water than we know what to do with, we'll be OK, but the west currently lives off rapidly emptying aquifers, and once those are pumped dry, the population will revert to 1700s to 1800s levels, possibly a little lower. Farmable land minus aquifer irrigated land, will be an interesting math problem for our kids.
The roll forward of progress was heavily advertised and seems orderly. The roll back is going to be completely disorganized and chaotic.
Jokes aside, it won't be easy, it won't be nice, but I'm pretty sure that if it comes to it California could start desalinating the Pacific. It will provide them with something to do for all that cheap solar power that's probably going their way in 20 years or so.
Once they get the ball rolling they could even export that fresh water, if it becomes so scarce...
Progress is pretty likely to continue.
Which ones are those? The last thing the world needs is even more consumerist culture.
I'm sure countries in Latin America, Africa and South-East Asia are also seeing an overall increase to their standard of living over the past 30 years.
Even if it correctly peaks at 2065, even if it declines, it should stop at a stable level since most developed nations usually have 1-2 child per family today. I cannot imagine the next generations doing nothing with a laid back attitude and slowly let us die out because nobody wants to make babies :)
If you throw out small island nations your trend lines will probably be a lot more accurate.
Hyperbolic Growth of the World Population in the Past 12,000 Years: https://arxiv.org/pdf/1510.00992
For each nation, he extrapolates various existing trends. This wouldn't be too bad if people within each nation were uniform. They are not. Given the choice between having children and having other luxury, people do not all make the same decision. The mental traits that influence this decision are inheritable, both genetically (brain structure and chemistry) and culturally (religion and more). It should be obvious that the portion of people who decide to have kids will increase. We'll be back to exponential growth until we hit real resource limits and start dying in squalor.
This is unavoidable. Anything done to stop it will be overcome, because those best at overcoming impediments to reproduction will come to dominate the gene pool.
