Dr. Roger Pielke Jr, [‘Pielke the Younger’ around here] my go-to-guy for science policy related topics posted a video on his excellent blog produced by NPR entitled, “Filling Up – 7 Billion, How Did We Get So Big So Fast” a several days ago which hasn’t attracted much comment, but was particularly interesting to me in light of having spent an electricityless weekend two weeks ago reading David P. Goldman’s [the online columnist ‘Spengler’ over at Asia Times Online] very new book, “How Civilizations Die, (and why islam is dying too)” – a must read for people interested in the geo and socio-political implications of demographic trends [well worth looking at as long as you remain aware that his thesis has some theoretical limitations] If you are frightened of the Islam angle for some reason, it is possible to subtract out that aspect and you still come up with a fascinating thesis – which I will let you read the book to discover – or maybe I will write more at a future date.
The take away I will leave you from that book is that the radical decline in fertility rates in the Western world in the last three centuries and the currently collapsing fertility rate in the muslim [you didn’t know either?] and much of the developing world requires a radical rethink of the neo-Malthusian paranoia, of overpopulation apocalypse we have been force fed since the Ehrlichs and their ilk made their onto the scene in the ’60’s and continues to be a core assumption of a great many people, as we grope out way forward into a global future that may be dominated by demographic decline rather than a population bomb. In other words, it reintroduces that concept of depopulation to the modern vocabulary, which used to be a subject of great concern in the premodern and classical worlds.
I have some thought on what I perceive as some structural flaws in the NPR video presentation Filling Up that touch on some of the main conclusions of Goldman’s book. The tie in to the NPR video presentation is that it represents a popular but flawed presentation of the past and present situations in the change of global population that severely limit its value as a heuristic, and dangerous to use as a predictor of future population trends.
My chiefest complaint about the NPR video production itself, as high as the production values were, and as generally accurate as it was [as far as it went], it did not explain that its conclusions were based on only one of three UN scenarios for global population trends, the Mid Range Projection and neglects the Low and High Range projections.
The text on the accompanying NPR page goes into a little more detail mentioning at the very end that small changes in fertility rate could cause population to continue on up to 15 Billion by the end of the century, never mentioning the Low Range estimate  which is that global population peaks at only about 7.5 billion and declines sharply there after. The correct interpretation would be that small changes in fertility rate could cause wide deviations to both the high and low sides of the Mid Range projection and would likely cause completely different problems.
The video failed almost completely to include in its discussion of the effect of a massive shift in fertility trends that will have dramatic consequences, possibly dominating other factors, in the future once we have passed the 7 billion threshold. They have left out changes in a dominating variable in the equation, which makes understanding our global population future impossible past the very near future once we pass the seven billion mark.
The subject of the broadening of the accelerating decline world wide of fertility rates and its causes and effects is completely overlooked, such as why the red, orange and green glasses are filling so much more slowly than the others and how that will impact different parts of the world differently.
I could at this point simply devolve my argument merely into bashing those of the mean green meme [to borrow a term from Ken Wilber] at NPR for committing a serious sin of omission, and leaving the trend line [hystericallyl] running a steep upwards slope at the maximum projected value – and ending on a note of panic and fear – the finite glass runneth over, oh dear.
As an aside, I find particularly ironic is that the group of people [still] most concerned about the ‘population bomb’ scenario is also the ideological group most likely to find itself in the Shakerite dilemma, facing near term extinction due to an ideological unwillingness to propagate itself through any means other than ideological conversion [or coercion].
That would miss a significant point, two actually. One being that having become habituated over the last few decades to think of global population as an impending population bomb we may be missing an important change in the trend of the trends, which is the broadening and the accelerating decline world wide of fertility rates, that’s a change in two variables: breadth and speed. This will, according to Goldman impact the sizing and timing of max population on Planet 3 and how steep the decline could be after, at least for societies that are unable to stabilize their populations, or bring their fertility rates back up to at least to a replacement level, which is the subject of Goldman’s book.
Second point and is one that everyone needs to keep constantly in mind is that when there are sociological factors involved, having a good understanding of the forces that are driving those variables when faced with having to choose between various models and their predictions, rather than defaulting to what ever tends to confirm our biases.
Goldman reintroduces the word “depopulation” to our modern vocabulary as a serious problem as it was for previous civilizations. Prior to the advent of modernity depopulation was an abiding concern of humanity, maybe even the abiding concern of humanity as a whole. History, Western history anyway, is littered with the carcasses of societies that joined the archeological record because they stopped having children: the Spartans, the Greeks, the Romans….
Even up to the modern day, lack of demographic growth has had major impact in shaping world history. Modern era France’s military strategy in the years leading up to both WWI and WWII was driven largely by its inferior demographic position to its natural enemy Germany. We all know what happened there for the French in the two world wars, nearly lost the first one, and wiped out quickly in the second.
Question: Have you noticed that the projections of maximum human population gets revised down by about a billion every couple of years? Funny that.
For instance the recent UN 2004 High Range Projection for global population projects the Earth undergoing gravitational collapse under the weight of 14 billion human bodied by 2100, the Mid Range Projection has population peaking at around 9 billion around 2080 and beginning a gradual decline thereafter, and the Low Range Projection peaking at a little over 7.5 billion in 2040 leading to a precipitous drop there after. How do you choose what to believe when the alternative projections diverge so completely? The process does not seem to be a very rational one in most cases – it seems to be based almost completely on your ideological/religious preferences, and your basic level of paranoia about the future.
Making models to understand a complex situation, necessitates simplifications, the only question is have we over simplified to the point that our model is no longer useful as either a heuristic or as a predictor of future events – the latter being far the more difficult proposition. It also has to clear which function a model is capable of fulfilling, even a flawed model can be useful as a heuristic, but even then it can be inappropriate to use for that function if its simplifications become serious methodological flaws.
Empirical science and the projections about the future often that it generates, almost always rely on the logical formalism of ceteris paribus, the notion “all other things being held equal” in order allow the analysis of complex phenomena in a way that can be solved mathematically, or understood easily. The problem is that all things are never equal, especially in the realm of complex, dynamical or evolutionarily systems.
From the Wikipedia article on cetis paribus:
Such assumptions are also relevant to the descriptive purpose of modeling a theory. In such circumstances, analysts such as physicists, economists, and behavioral psychologists apply simplifying assumptions in order to devise or explain an analytical framework that does not necessarily prove cause and effect but is still useful for describing fundamental concepts within a realm of inquiry.
“Does not necessarily prove cause and effect”, what this means is that such analyses will also necessarily have uncertain or limited predictive value, which reminds us strongly that analyses and models of complex, and dynamical systems may be of some use as a heuristic method, but may have little predictive skill in the real world, and can certainly never be used without strict attention to the uncertainties involved, particularly in regards to the unknown unknowns inhabiting the fourth quadrant domain of ‘Extremistan’.
The problem with population projections in general is that the set of assumptions about what fertility rates will be world wide, birth and death rates & etc. that are used to parameterize the variables in these projections are as set of constantly moving targets, which in the case of fertility rates are undergoing rapid evolution worldwide. It is difficult or dangerous to assume that future trends in society will cause them to behave in a way that will allow us to make good long term predictions if we do not have adequate understanding of what drives these variables, particularly those driving fertility rates.
There are of course also the prospect of other unpredictable evolutionary changes in society, the [so called] ‘Black Swan’ events [positive and negative] that await us in our ever compressing future, which may make all of these predictions completely obsolete before they can ever be fulfilled. For instance what happens to global population projections when biomedical technology starts delivering technologies in the next twenty years that may provide functional immortality? [to those who can afford it anyway] people might stop having children altogether – or – when by 2100 or so we find that humanity has shed the monkey body completely and we all wander barefoot the sandy beaches of our virtual imaginings in supercomputers buried deep beneath the Earth, as we simultaneously supervise the rewilding of the Earth, the dismantling of surface civilization and prepare to travel to the stars?
Our demonstrated lack of ability to forecast the challenges of solutions that await us in future, should not be underestimated. What to do then? Find other criteria for deciding what to do and what policies to enact and remove areas of fragility from our lives and economies.
One thing is near certain, what we imagine will eventually come true.
As my buddy φ said recently:
“If you have values that you cherish, have children.
You vote for your vision of the future with your children
– and the number of times you vote counts.
PS. for more on Spengler you can find a link to him in the sidebar.