I think we’ll really see how sustainable we are when we come up against sudden, large scale crises - our agricultural methods are productive, but not very sustainable. What if we deplete our soil nutrients to the extent that they aren’t able to produce as highly as before, or screw with our food production in some other way? (loss of pollinators, desertification, pollution, loss of a region’s access to fresh water etc.). Things can continue to work pretty well until they don’t, and that change can happen quite quickly. A lot of humanity is based near the coasts, so can we cope with large groups of people having to move due to climate change? Our own lifestyle is horribly unsustainable if we have any sense of justice - of course people in other parts of the world also want a variety of fresh food, comfortable, air conditioned living spaces, personal transport, computers etc. They deserve it at least as much as we do, and large numbers are starting to get it.
None of this means that we can’t be sustainable, but our civilisation has been built more on the ability to overcome obstacles and continue to grow rather than the ability to self-regulate. It will be interesting to see if we’re able to adopt a suitable change in philosophy before it’s too late, because it will be by the time we all agree that we have to change.
If it’s not an exponential curve, then what is it? Perhaps part of the cognitive problem here is that population growth is often quoted as a percentage of the current total (see https://en.wikipedia.org/wiki/Population_growth) which is inherently exponential. But the description is then that the exponential growth rate is dropping. This is what you would get if the growth rate was actually linear. Which is what you would see if the time to add a billion people is pretty much constant from 1960 to now and predicted to stay constant till 2025 at least. And that’s what’s quoted at that link with each extra billion taking 12-14 years. That may not be exponential, but it’s still a huge rate of growth and it’s not slowing down. Currently that 12-14 years to add a billion people is not extending. There are arguments that improved education, resulting drops in the birth rate and so on will result in fewer additional people each year and that it might even go negative but it’s not happening yet.
The more extreme predictions of people like Bartlett and Erlich that total population will keep accelerating because the exponential growth is constant may be inaccurate and exaggerated, but that doesn’t mean that population growth has gone away and the results of that aren’t a problem. Both now and in the short term future (<75 years, 1 lifetime). Even Joel Cohen in the papers described in TFA recognises this. So I don’t really see how linear instead of exponential growth is a justification for much optimism.
Well, there’s reasons land is cheap in Siberia. Reasons people don’t want to live there.
There are good reasons why people want to live in expensive cities.
Like a peak hour subway train, you can always squeeze in a few more. You could get people to hang on outside if need be. But you’d rather a less packed carriage where everyone has a comfortable seat.
I don’t think exponential population growth is a myth. What you pointed out - the decline in the population growth rate, can be interpreted as the result of interventions (provision of birth control, better education) that has mostly dealt with the issue. If you even simply stuck with what Malthus said, the point is not that population will grow forever, but rather that it will eventually become limited by one way or another - and either that’s by controlling the birth rate, or its by widespread famine leading to mass deaths. The population projection is really about the pressures on the system.
That doesn’t mean there never was a problem and it certainly doesn’t mean we wouldn’t be vigilant in the future.
I’d say we’re in a state of under-distribution of resources, rather than overpopulation. Ofc, that’s only absolutely true from a purely humanistic point of view. In the context of the biosphere and our effects on it, the picture is a little more muddled.
I think the adverse effects on the planet are more due to the incentives toward harm along with the modes of production and consumption than to the overall number of humans on Earth.
This style of argument is common to a whole series of both optimistic and pessimistic modelling that are important just now. For instance, Population growth will slow at some stage in the future because the 3rd world will recapitulate the 1st world and drop birth rate as they become more educated. So the growth curve will flatten out at some stage in the future. Except it hasn’t started doing it yet. Here’s another one. CO2 concentration, CO2 emissions and Global temperatures will flatten out in the future, peak and start dropping. Except they’re currently all still accelerating and show no signs of slowing down, yet alone reaching a peak. In each case you can argue that just because the current curves match the model, doesn’t mean they will match the curve when our model says they’ll change from a continuously rising smooth curve to something else.
Which is to completely misunderstand the point of the model. And actually to misunderstand the point of LtoG. The LoG models try to understand what happens when continuous growth meets finite resources in the real world. Where we are following a line of continuous growth towards the limits in the Earth’s resources and carrying capacity. We’re still just about in the continuous growth stage, following the models predictions. The resource constraints on the horizon are becoming more and more obvious. So arguing that it hasn’t happened yet and so will never happen is just foolishness because it ignores another part of reality. exactly the art the LtoG models are trying to understand. If you think the models are wrong, then suggest something else. Obviously that doesn’t mean creating another model yourself. A cite will do.
This thread pushed me into a bunch of research. One thing I tried to find and wasn’t really successful with was figures for yearly growth in global population in absolute numbers. As near as I can find it’s hovered around +80m/y from 1980 to now and really hasn’t changed much up or down. This is constant straight line linear growth. There’s no slow down or rise. It also led me to a bunch of techno-optimistic bets from people like Kevin Kelly and Stewart Brand from early this century. eg this one from 2003 http://longbets.org/118/ “By 2060 the total population of humans on earth will be less than it is today.” Or this from 2009. http://longbets.org/510/ “Human population of the world will peak at or below 8 billion in the 2040s and then drop dramatically.” Both of these look like a Grue to me. There’s no evidence in the historical record or currents statistics but we’ll wish on a star for a happier outcome some time in the future based on some hand-waving about human nature. Both bets currently look very unlikely with business as usual. However, both bets might be right if we get some Black Swan events like severe water shortages in the most heavily populated regions and/or Black Flag weather. Ironic then that they’re born out of optimism but are only likely to come true under the most pessimistic doom scenarios.
Which gets to the core of what bothers me about articles like the OP. It feels like they reflect a particular brand of techno-optimism common on the left coast of the USA and the result of an inward looking view. What does the world look like from California and does it include the 3.5B people in SE Asia (India, China, Indonesia, et al) where this stuff will get decided?
Distribution of resources looks positively sadistic, but that’s extra significant because we’re pushing the natural system far beyond its limits.
Technically we can feed the whole of humanity, but that means either a very limited diet or rampant resource inequality.
7 billion people is incredibly taxing on the Earth (large fish almost gone, forests disappearing, climate changing, overcrowding). We’re far, far beyond any reasonable ideal of population.
Yes, that’s not exponential. “Exponential growth” has a particular meaning. Expressing linear growth or some other kind of growth as a percentage doesn’t make it exponential. That’s just a plain misuse of the term. Even if we leave out rigour and just talk colloquially, I don’t see how the term “exponential growth” can be defended unless something is at least growing at an ever increasing rate. You may feel we already have a population problem, but that doesn’t make “exponential” anything but a myth.
Just came across another example that graphically illustrates the problem. A straight line graph that is marked up with the percentage rises showing that the percentage growth rate is dropping. And yet the graph is very clearly rising and the gradient isn’t changing. Until a time in the near future (10 years) where the linear growth starts to slow down.
No one actually thinks we will ever get that high. Current predictions are that we will never get higher than about 10 billion and then the levels will fall back down to about 8 billion.
Don’t believe me? Just ask the UN! Ask any of the modelers. Extrapolating from current trends and the knowledge that population growth stagnates as countries achieve prosperity, we will never hit 12 billion. We will be lucky to break 10 billion.
This is the problem perpetuated by idiots like Paul Ehlrich. You can’t look at something as complex as population growth and attempt to model it using a straight-line approximation. The idea that humans would experience some kind of “population cycle” is kind of ridiculous, since population cycles are a rather isolated phenomenon in nature. You can count the number of species that “boom and bust” on your hands and toes.
