

Another Look at "The Limits to Growth" - inetsee
http://www.smithsonianmag.com/science-nature/Looking-Back-on-the-Limits-of-Growth.html

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jbooth
So, I'm as concerned about environmental and energy concerns as the next guy,
but I noticed something about this graph..

The big predictions haven't happened yet. The part where we're tracking
perfectly is just an almost-linear continuation from where we were before. You
can make the case that that's unsustainable (and I'd be convinced), but that
doesn't mean this model's predictions are borne out by data we've seen so far.

~~~
olalonde
My thoughts exactly. Fixed the graph to reduce bias:
<http://dl.dropbox.com/u/3750008/Screenshots/r.png>

~~~
Eyght
I'm curious if the decline in industrial output per capita can be explained by
the increase in population alone, or if it has decreased more than that.

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jonmc12
Criticisms of World3 model:
<http://en.wikipedia.org/wiki/World3#Criticism_of_the_model>

The new book, Abundance, has an informed point of view that speculates an
opposite reality in future: <http://www.abundancethebook.com/qa-2/>

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nfassler
If you want a more nuanced discussion of the topic, check out the recent talk
by Dennis Meadows, the originator of this chart. This is from an event by the
Smithsonian commemorating his book, "Limits to Growth":

<http://youtu.be/f2oyU0RusiA?t=5m45s>

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victork2
Sorry to say that but we cannot trust the weather forecast in simulation for
more than 5 days and we trust a forecast for mankind 30 years from now?

I know people like these kind of studies, perhaps it conveys the feeling that
"after me there won't be anything" and that we are the last generation but
it's simply to complex to model. People have been saying the same things for
generation and so far, so good (with some exceptions of course).

I am not saying that it's not going to happen, just that you have to be very
careful with prediction such as these, take them as "work of fiction". Also
don't forget a possible bias. Apocalyptic vision have always fascinated
populations and men around the world but how many have happened?

~~~
kragen
You can't tell whether it's going to rain five days from now very reliably,
but you can predict within a degree the average monthly temperature in any
city in the world, for any month of the year, five years from now. Of course
there are unforeseeable events, but that doesn't mean everything is
unforeseeable.

In this case, we've had 40 years to test this forecast, and it looks like
they've done a pretty reasonable job forecasting the key variables they were
forecasting, 40 years in the future. That seems like a good validation of
their model, and we should expect it to do nearly as good a job for the next
ten years at least, if not 20.

So I don't think they should be taken as a "work of fiction", even if they
might be wrong. The model should be taken seriously, and we should attempt to
improve it or propose better models, even if those models have more
uncertainty in their predictions.

There's a big difference between predicting an apocalypse based on a psychotic
episode and predicting an apocalypse based on a dynamical model of the key
variables in a world system.

~~~
randallsquared
_You can't tell whether it's going to rain five days from now very reliably,
but you can predict within a degree the average monthly temperature in any
city in the world, for any month of the year, five years from now._

So the extremely mild winter (in the continental US) that everyone's been
saying was so shocking was actually forecast years ago? Or are you saying that
this capability has only been developed in the last year or so?

~~~
kragen
I'm not talking about anything new. Your predictions will be wrong
occasionally.

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dclowd9901
What I don't understand about these charts is they completely dismiss the
impacts of diminishing returns.

Suppose the population continued to grow and grow and grow. What would happen
to available non-renewable resources? They would become more and more
expensive _to a point that their cost would exceed the cost of finding
alternate means of producing energy_. What happens then? we stop relying on
fossil fuels, and start relying on more sustainable energy sources, as a
practical matter of the economics of it.

Food production isn't a non-renewable source, but it is a control. Only so
many people can afford so much food; at a point it will be prohibitively
expensive to procreate. If they can't children die, or families stop having
children. Does that mean _all_ population growth will backslide? No; why would
it? It just means there becomes a harder cap on how many children a person or
family can afford to have. No more 3+ children in families.

~~~
refurb
Agreed. These predictions assume that behavior never changes. Just like when
gas prices skyrocketed a few years back and you could buy a SUV for a fraction
of the value a year ago.

Another great example is oil. When oil was cheap and plentiful, people
screamed "we're running out!!". Prices went up and suddenly it was
economically viable to frack and extract from tar sands. Boom, we have a bunch
of "new" oil.

~~~
dclowd9901
One takeaway I got from the oil uptick a few years back (~$150/barrel, if I
recall), is that people _will_ change their behavior. In 50 years, driving
habits continued trending up and up, but in that time people actually _drove
less_.

It doesn't take a genius to figure out what that means. They actually
_changed_ their lifestyles to accommodate the pinch they felt. Carpooled. Took
fewer road trips. Consolidated trips. And it wasn't even an issue of shortage;
it was purely speculative increases.

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wazoox
For those interested on well documented complements to this, don't forget to
check the "Do the math" blog: <http://physics.ucsd.edu/do-the-math/>

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scottw
"Population declines following economic collapse" should be "Population
declines following sustained drop in birthrate." The population is going to
decline regardless of what the future economy does.

~~~
kragen
I'm not very familiar with their model, but if the birthrate asymptotes to
above the replacement rate, or goes back up, the population won't decline. So
the economy might be a factor.

~~~
schiffern
scottw is referring to the well-studied _demographic transition_.

<http://en.wikipedia.org/wiki/Demographic_transition>

~~~
toomuchtodo
TL;DR The world is getting older, hence less babies born.

~~~
toomuchtodo
Downvote? For quickly summarizing a wikipedia link? I guess we all have time
to waste skimming wikipedia articles, don't we?

~~~
schiffern
The problem is that it's wrong.

A better summary would be, "The world is getting richer, hence lower infant
mortality, hence birth rates drop."

~~~
toomuchtodo
The world is graying extremely quickly (Japan, Western Europe, the US, and
soon China).

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api
I'd say right now that everything looks great -- very optimistic -- unless you
look at two areas: energy and politics.

If you look at energy and politics, everything looks apocalyptic.

~~~
ChuckMcM
I'm not so sure about the energy side, we've got a number of folks who are
making real progress in both solar efficiency and energy storage. We have new
nuclear processes that were once derided (cold fusion) being quite durable
(while most folks don't have a good explanation about what is happening, more
and more of the community is convinced that something we don't know about is
happening at these low energy levels) We are getting hints of some of
superconductivity's secrets which has the potential to eliminate distance
constraints on energy transport, and we know _how_ to build nuclear plants
that are walk away safe and can consume their own waste leaving behind some
easily manageable and easily containable waste products.

~~~
kragen
> more and more of the community is convinced that something we don't know
> about is happening at these low energy levels

[citation needed]

I agree with the solar-efficiency and energy-storage points, though.

