Understanding the Limits to Growth

The club of Rome’s 1973 the limits to Growth, warned of serious possible dangers of constraints to continued growth (economic, population, prosperity, industrial output, etc.) brought on by a depletion of resources and severe damage being ultimately inflicted on the ecosphere. Unchecked this could potentially lead to the eventual collapse of civilisation, or at the least a severe curtailing of it.

Unfortunately, anytime one starts talking about resource “constraints” or “limits to growth” you inevitably get one of two responses. Some will call you a “doomer” or a “Malthusian” or a member of the club of Rome. Others will nod in agreement and explain how this is why they live in a bunker under Idaho (and the lord is coming soon….I actually had a conversation with a scary Tea-partier which went something like that!). Of course, the truth as always lies somewhere between these extremes!

While sponsored by the Club of Rome, the research behind the Limits to Growth was largely compiled at MIT. …….I should note that you’ll encounter quite a number of strange conspiracy theories (a couple of good examples of such craziness can be found via a google search), usually originating within the Anglosphere surrounding the club of Rome. The only obvious evidence I can find is the assumption that lots of wealthy foreigners meeting in a foreign country & speaking a foreign language (gasp!), well they’ve got to be up to something bad!

The Limits to Growth is often ridiculed by critics, who will tell you the book predicted world catastrophe due to resource constraints by the year 2000, which obviously didn’t happen, so the group’s predictions are obviously wrong.

Well actually no, the “limits to growth” never once mentions anything about disaster by 2000, indeed they go out of their way to avoid making any specific predictions. Furthermore the study period detailed in the book runs from 1970 to 2100 (not 1970 to 2000), with the bulk of the focus on the post-2000 era. Indeed while the book does show a major risk of several possible global resource crunches coming sometime in the next century (or as it is now, this century), generally these aren’t predicted to hit until sometime between 2030-2070, and then such resource crunches will only happen if we ignore the problems that they’ve highlighted. Also the book itself is very careful to point out the flaws in some of its own projections. They were not trying to create some sort of Nostradamus like predictions of the world’s future.

Indeed it’s interesting to see how some of the trends they did produce some numbers on, usually with many strict caveats of course, have proven to be remarkably accurate. For example they predicted a global population in the year 2000 of just under 6.1 Billon (it was 6.5 Billion, thought they did caution that it could hit as high as 7 billion), they predicted CO2 levels would rise to 370 ppm by year 2000 (it was actually 380 ppm). This doesn’t sound to me like a highly inaccurate set of forecasts, especially for a body of research that goes out of its way to avoid making any specific predictions.

If there was one point the authors were trying to get across it was the danger of ignoring many global problems (pollution, population growth, declining farmland area, unchecked resource consumption) due to the nasty consequences that occur when an ultimately finite resource is attacked by an exponentially increasing consumption rate.

Exponential consumption – why the party’s over!

There is for example the parable of the pond with a single water lily in it. Every day the number of lilies doubles in size (day 1 there is but a single lily, on day 2 there are 2, then 4, then 16 then 256 and so on). If the lilies cover the entire pond then they will starve the life below of air & sunlight and the pond will die. We assume it will take 30 days for this to happen. If you take the sceptics view, that no action is necessary until half the pond is covered, at what point will you take action? The answer: day 29, the day before the pond is killed! This is the danger of failing to keep an exponentially growing problem in check. In all likelihood by the time it obvious that disaster is imminent, it may well be already too late to do anything to prevent it.                                                                                   http://eatourbrains.com/EoB/2007/03/page/2/

Another example, let us suppose a man (or woman!), henceforth known as the host, throws a party. In order to keep the revellers happy the host stocks the fridge with 200 bottles of beer (well I am Irish, how else am I going to explain anything!). How long with this stockpile of beers last? If we assume that each party goer drinks roughly one beer every hour, then 200 beers will last 10 people for 20 hrs (or however long it takes for them to all get drunk and fall down!), 20 people for 10 hrs, 40 people for 5 hrs, etc. However, let us suppose instead that after the party starts the host and the 9 other initial guests all text 1 friend, tell them that there’s this great party with free beer and invite them along (granted doesn’t sound like much of a party, what with everyone sitting around drinking exactly 1 beer at an exact rate of 1 hour each, but we’ll assume the pubs are shut & there’s nothing on telly!). When these new guest arrive, they all text 1 friend and invite him/her and so on. These new guests begin to arrive at regular intervals over the preceding hour, so after 1 hour there are 20 people, then 40 at the end of the 2nd hour, 80 at the 3rd and so on. All the while the beer supply is being consumed in every growing quantities.

The host has a strategy to avoid final depletion – when the fridge is half full (or half empty depending on your point of view!) he will dispatch a friend to the nearest off license to get another 200 beers. We will assume that this will take 1 & ½ hours to complete (drive to the offy, buy beer, return, restock the fridge and give the beer a good 30 minutes to get cold).

At what point do we hit ultimate exhaustion of the beer supply? A little after the 4th hour (about 4 hrs and 20 minutes to be exact). At what point does the beer supply pass its mid-point? About 3hrs and 25 minutes – insufficient time to restock the fridge! And it gets worse, for even if we can convince everyone to hang around & nurse their drinks for the brief delay as we wait for the fridge to get restocked (or just settle for warm beer!), by the time this new stock becomes available there will be just under 200 revellers present, so the new stock of beer will get consumed almost immediately after it arrives. By the beginning of the 5th hour, sustaining the party will require a further stock of 320 beers (160% of our original stockpile of beers!) just to sustain the current population of party goers for just another hour. By hour 12 we’ll pretty much need all of theUK’s alcohol supplies to keep a group of revellers the size ofGlasgow happy (hmmm….sounds likeSauchiehall Street on a Saturday night!).

The point I’m trying to make here (aside from the benefits of always bringing carry out to a party and being careful who you invite!) is the consequences of assuming that an exponentially increasing rate of demand being imposed on an ultimately finite resource can be sustained indefinitely. This is of course precisely the point that has to be made about such issue as global warming or peak oil, waiting till the fridge is half empty (or the pond is half covered) means taking action when the scale of the problem will likely be too vast to contain, at least without shutting down the party. The current global “party” of conspicuous consumption might soon need to be halted or curtailed.

Hidden Dangers

Indeed the examples above actually belittles the issue, there was a fatal flaw in my logic above, notably that in both cases we could clearly observe the growth of the problem. A quick glance told you how many lilies were in the pond or how much beer is left in the fridge. In reality we are blind the scale of our resources. We simply don’t know for sure for example how much oil is left worldwide, or how much pollution the biosphere can withstand or how much global warming is too much. And the attitude of various critics (such as global warming deniers) doesn’t exactly help matters.

So it’s probably better to replace our fridge of beer in the party above with a keg of beer. Our first indication of impending final exhaustion of reserves will not come until the last couple of pints come out increasingly gassy. Of course just as discussion about the possibility of running out begins and talk of whose turn is it nip down to the off licence, up pops our cornucopian sceptic and says not to worry its just a phase that kegs go through, and final depletion is still along way off. In either case the chances of corrective action being taken are even less likely than before and the arrival of final depletion will be all the more sudden, and the resulting resource drought that follows will be all the worse.

The Ultimate Resource

The main counter argument to the conclusions drawn by the limits to Growth by economists is to claim that it ignores economic factors. If resources become scarce, prices go up, leading to conservation of supplies and a strong incentive to seek out additional reserves. Also, in the case of many mineral resources, recycling is encouraged by high prices.

Actually, the Limits to Growth devotes a good deal of its time to the discussion of economic factors and they do point out the effect economics will have on a diminishing supply of any resource. In many cases they assume that the amount of, say copper in the world, is 5 times the known supply in 1970. Even such vast assumed reserves cannot hold out against an ever increasing rate of consumption for more than a few years longer. The only way economics can prevent final depletion is by making the resource so expensive that demand is effectively killed off. Of course the problem with this is that whether the last of the world’s oil ends up being all used, or it stays underground in vast untapped reservoirs (or in bank vaults!) because its way to valuable to just burn, well that’s sort of a moot point as in either case its use as a source of energy has been eliminated.

A key fallacy however, of cornucopian theory is that it ignores the principle of “cut off” grades. That is, below a certain threshold it is not only uneconomic, but hopelessly impractical to extract a certain mineral resource. Lowering cut off grades does increase reserves, but not by much and at a huge cost. For example in Chapter 10 of Energy (G. J. Aubrecht) points out that decreasing the cut of grade of mercury by a factor of 6 only increases our yield by 50% but involves handling 4 times as much material (i.e. more dumper trucks, processing plant, waste, man hours, energy, chemicals, etc.). He cites a similar example for copper. So clearly the price of either substance would have to increase considerably before the above would be economic, and of course we’re assuming that our separating mechanism are sufficiently capable of separating the ore out at this reduced grade. In all probability simply using less of said resource, recycling, getting by without it or using an alternative would all likely prove cheaper than engaging in such an enterprise.

Then there’s the matter of energy returned for energy invested or EROEI. This states that if you, say, wind up spending more energy getting oil out of a Shale deposit than you usefully get back when it is consumed at standard cycle efficiencies, you’re oil shales are actually an energy sink not a source. Such a process is only sustainable so long as the energy feedstock into the system (typically coal and natural gas) remain in plentiful supply. In another example many nuclear energy supporters will cite the Clarke grade amount of Uranium suspended in water (rivers and oceans) as a potential uranium resource. However, this ignores the principle of EROEI above with several peer reviewed papers (Barti 2007 and Barti etal 2011, Dittmar 2011) claiming that such a process would likely yield less energy back than it returned. Such proposals also ignore certain practicalities. Barti suggests that we would have to cover the whole of North Sea with Uranium adsorption structures in order to get enough uranium for just 16% of the present world’s electric power production. Dittmar suggests that you would need to capture and filter the flow of 5 times that of the Rhine river to run just one nuclear power station, so clearly impractical! Of course building a dam and using such a flow for hydroelectricity would yield substantially more energy as would covering a small patch of the North Sea in wave energy machines, but the point is that such vast schemes ignore practical day to day realities.

Just to counter any possible arguments about the ultimate reserves of various metals or energy sources, in a couple of the test runs in the Limits to Growth, an assumption of unlimited resources (i.e limitless energy, metals, coal, energy, etc.) is made. The consequences of this? Final collapse is at best delayed by a few years (ultimately food production or more to the point too many people proves to be the ultimate constraint) or in some cases collapse occurs sooner than it would with less assumed resources, largely due to the huge spike in pollution levels and environmental degradation.

I’ll wager you a world

In 1980 the Biologist Ehrlich (a promoter of Malthusian theory) bet the economist Julian Simon (a cornucopian economists) that the price of 5 key metals would rise between their 1980 price and their 1990 price. Instead they actually fell. This, and the more recent Simmons-Tierney bet (over oil prices), is often cited as “proof” that the LtG are wrong. Not so, it merely demonstrates that commodity prices are a bad proxy for the availability of any commodity, as the spot market price merely reflects current supply v’s demand conditions. If the world is in recession (as it was when both of these bets expired) then the price of said commodities will be low, regardless of what’s happening on the supply side.

Also there is market speculation to consider, if the spiv’s and speculators on Wall Street are betting that fibre optics are going to take over the world, then copper prices will be low, even if supplies are so scarce that metal thieves are robbing everything that’s not bolted to the floor (or indeed these days they are undoing the bolts and stealing them too! I’m just waiting for that Wall Street Bull to disappear one night!).

Of course this also works the other way too. Many have interpreted past spikes in commodity prices (such as the 2008 spike in oil prices or the 2007 spike in Uranium prices) as a sign of impending “peak” in those resources. However, in many cases market forces (or a flooded mine in the 2007 Uranium spike case) may ultimately proved to be the more likely cause of such spikes.

Armageddon delayed

Another criticism of the Limits to Growth is that it relies heavily on system’s theory . That is, to say that we can build a massive mathematical model that will replicate future human behaviour and consumption patterns. Inevitably such models tend to be flawed as they often assume trends far into the future that are ultimately not sustained. Many of the Malthusian school of thought have made the mistake of assuming rates of growth in the consumption of any resource that are simply too high, or indeed they have just drastically underestimated how much of said resource remains. Unfortunately, the mathematical rules means that such a mistake can lead to a drastically different outcome. With our beer example earlier, for example, if we re-run it with only half the people invited actually showing up, we can stretch the party out for a 6 hour run with just our initial 200 beer supply. If someone shows up with a bottle of Whiskey (causing a reduced demand of beer) it would run for even longer, thought inevitably the final phase of depletion  is still the same (i.e it occurring much more quickly than we can reasonably act to offset its effects), just it occurs later than our original model predicted (plus a whisky on top of beer hangover is the worst you can possibly have!).

Take oil production for example. It has seen periods of rapid growth (easily exponential), but interspaced by lengthy periods of sluggish growth and a few declines. This is often due to the fact that oil companies going off on a drilling boom when the price is high, but when the next recession hits finding they are over-producing and in the middle of an enormous oil glut (and consequently cut back on both drilling and exploration activities). Politics has also played a role (companies and countries grab oil offshore before their rivals get to it first) as has the growth of other energy sources (notably natural gas) that compete with oil. http://en.wikipedia.org/wiki/Predicting_the_timing_of_peak_oil

It is this mechanism that has often let Malthusian’s to predict Armageddon a little early. For example, Ehrlich predicted a global population time bomb hitting in the 1980’s (which obviously didn’t happen). The key flaw in his analysis was to assume a much higher rate of population growth and neglecting the advances of technology (such as the so called green revolution). This is a common occurrence as regards the predictions of “peaks” in any resource, the proponents of which are frequently forced to continually postpone doomsday.

Of course eventually, given that our resources are finite and demand is growing (thought at a slower rate and less steady rate than some of the pessimists believe) eventually the “peak pessimists” will be right and many of our resources will exceed their principle point of peak output. The only question is when will it happen? and what sort of slope will we see the other side of said “peak”? It could be a long gentle decline (as the optimists suggest) or a sudden abrupt cliff. It’s difficult to say which at this stage. Some resources, such as Whale oil have undergone a fairly sudden collapse in output after supplies peaked. By comparison oil production in some part of the world has remained static or declined relatively slowly, post peak. The oil production of North America for example, while it has declined significantly since peak in the lower 48 states, this has been offset slightly by new oil production from Alaska and Canada.

But even if we take the optimistic view that, say peak oil is not likely until the 2030’s, given that the Hirsch report suggested it would take any industrial society 20 years to prepare for peak oil, that would still amount to a need for immediate and urgent action if we plan on avoiding any post-peak oil complications. Also, given that we don’t know exactly when oil production will peak (again looking at oil prices is a bad way to determine this) we’re unlikely to know we’ve exceeded peak until several years after the event. In other words, like the beer keg above, the first sign we’ve peaked will likely come far too late for us to be able to do anything and thus a “wait and see” policy is simply not acceptable.

Limits to Growth Updated

The authors of the Limits to Growth produced an updated version in the year 1993, this corrected a number of flaws in the original model and countered quite a number of the criticism previously levelled at it (much as I’ve outlined).                  http://www.context.org/ICLIB/IC32/Meadows.htm

Also the author G. Turner, produced his own comparison between actual data output (i.e how much food or energy we actually produced v’s what the LtG suggested, as I noted earlier its predictions regarding pollution were reasonably accurate) and the “standard run” in the limits to Growth and found good agreement between the two. He cautions that if true then this implies collapse of civilisation sometime around mid century. I would caution however, that this assumes an “all things being equal” scenario continuing and that the “trigger” point of collapse anticipated by the LtG authors being accurate. It’s difficult to say if either of these points is true…but I won’t advise waiting around to find out!     http://www.manicore.com/fichiers/Turner_Meadows_vs_historical_data.pdf

The proponent of Peak Oil (the late but great) Mathew Simmons wrote his own synopsis of the Limits to Growth here. Again his analysis is that the projections of the LtG seem to roughly correspond with what actually happened (since 1970). And again it’s this inability of ours to indefinitely match growing demand with finite resources that is the key point to be drawn from the LtG.                                                                                           http://greatchange.org/ov-simmons,club_of_rome_revisted.pdf

Simmons also points out, a major flaw in the Limits to Growth, was its assumption of a very rapid rise in the wealth of the third world. Until relatively recently the opposite was happening, most third world countries were got poorer between the 60’s and year 2000. Its only recently that some, notably China, have succeeded in reversing this trend, but much of sub-Saharan Africa is still falling into an ever deepening poverty trap, which is reducing their consumption of resources to a lower level. So I think that’s hardly cause for us to start celebrating!


So in summary the Limits to Growth is not the dark Malthusian Cabal you’ve heard it to be. The predictions of the Limits to Growth aren’t “we’re doomed! And its already too late!”. No, we are only doomed if we choose to assume that infinite growth forever is possible on a finite planet….thought admittedly that seems to be the current policy of most countries and governments!


About daryan12

Engineer, expertise: Energy, Sustainablity, Computer Aided Engineering, Renewables technology
This entry was posted in climate change, economics, energy, peak oil, politics, sustainability, sustainable. Bookmark the permalink.

7 Responses to Understanding the Limits to Growth

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  2. Stan says:

    It was great to hear such a well written summary of L2G, particularly the responses to criticisms it has received. The Cornucopian view you refer to is interesting too. I think that despite the limits of the physical environment, the need to satisfy investment with increasing returns (i.e. an annual percentage growth rate – exp. growth) is struggling to be met even now. Just like diminishing returns. There may still be a lot of many resources left, but as you mention, the decreased EROEI ratio and simple limit to the throughput or flow of the materials, limits the amount an enterprise can produce. However they simply must produce more every cycle (that is, more than they did the previous cycle) in order to provide monetary return to investors. Economically, the current world hiccups seem to indicate this struggle, which is like squeezing a lemon: eventually the juice is just much too hard to extract. Even before sources deplete and sinks overflow, the growth curve can taper off due to simple limits to throughput, which will restrict output and hence return for investors. That is why an alternative to growth is very complicated. Any kind of alternative will be like taking wood off the fire on an extremly cold night. If an enterprise slows down or reduces profit, investment will fail and so will the enterprise. I think that is what is happening in the US now (July 2011). Debt ceiling is increased but huge CUTS are now required. Large companies are merging, workers are sacked – all this is to come up with new ways of continually increasing the curve of growth – without actually PRODUCING more. Even very simple things can I believe, indicate L2G. For example, computerised checkouts at supermarkets (that don’t take a wage home) less flight attendants on planes etc. I would very much like to continue this discussion. I used to write about Limits a lot on my blog, which at the moment has more of a poetry focus! However it has been very difficult to find another proponent of the L2G model. All the best to you! I look forward to hearing more from you.


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