Talk:Limits to Growth

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[edit] Runge Kutta numerical integrations

I remember reading a thesis done at the Colorado School of Mines. A chap tried to reproduce the study on a CDC and couldn't. The original study was done on an IBM which has much smaller floating point precision. The chap found many of the numerical integrations were not converging.

I have since looked for but have been unable to find the thesis - it would have been printed about 1973-1976.

Finding this thesis and verifying what it says would be a good thing to do because it means the study was mathematically not correct in addition to all of the other criticisms. Bascially GIGO. terr 03:00, 14 September 2006 (UTC)

Hmm. I wonder what are the exact changes between World3/1974 and World3/1990, since World3/1990 was designed to run on PC's. Jrincayc 03:57, 14 September 2006 (UTC)
Actually, come to think of it, I replicated the non renewable resource equations in python using doubles, Talk:World3_nonrenewable_resource_sector without noticing any serious differences. Jrincayc 12:22, 14 September 2006 (UTC)
This would make sense. The PC uses an IEEE specified format which has 80 digits of precision in the FPU and 64 typically in the floats.... however 80 bit floats can be used. The CDC machines had 120 bit doubles. Whether you use Python or any other language doesn't really matter.
I don't know how we can prove whether the Runge Kutta integrations converge or not... I think you'll have to do some digging. Numerical Receipes might be a place to start. I have the FORTRAN version but I'm comfortable with C and other languages. I have never looked at the source code and I really don't have enough time to do so - however I would be willing to work with you and write some functions you could call from Python to crunch some numbers. The issue is I don't think we can get 120 bit and I do know that if we adjust the steps on the RK integrations we are not suppose to need the higher precision. I do not think the code is the problem... I think the problem is the step sizes... I'd try playing there first.
What we really need is to find the Thesis. We do not know _which_ integrations the guy was talking about. Hopefully someone will step forth. BTW. Replicating doesn't prove convergence... it might just prove similar non-convergance... IE. The algorithm can head into the hills but in both machines it might have headed in a similar (worng) direction.terr
It is possible that Jay Forrester's DYNAMO simulator was used to generate the results. I used DYNAMO to investigate international exchange rates ~1972 using open difference equations. DYNAMO was written in FORTRAN and should be available somewhere. It ran on an IBM 360/370 platform.--Ozzie66 17:31, 30 March 2007 (UTC)

[edit] Exponential index formula

Limits to growth does not give the exponential index formula, so I had to rederive it. The question is how long with the resource be used up. Since the exponential assumes that there is a constant rate of growth, it can be done as so: S = \int_{0}^{b} e^{kt} dt where S is the static index (this normalizes the first years use to 1), k = ln(1.0 + r) where r is the annual rate, and b is the exponential index. So, after integrating and solving for b, this works out to b = \frac{\ln(k(S+1)}{k}. Jrincayc 20:58, 5 Dec 2004 (UTC)

Here is an example. On page 250-251, Introduction to Nuclear Concepts for Engineers by Robert M. Mayo has the following quote: "For the year 1995, about 4.7 \times 10^{30} J of electrical energy was consumed worldwide. Catalyzed D-D burning of seawater can then supply this constant rate for more than 100 billion years. Even allowing for a very liberal growth in electrical energy demand and complete elimination of all fossil fuel burning still does not detract from the conclusion. There is more fusion fuel available than earth inhabitants will ever need." So, for this example, the static index in 100 billion years, or 1e11 years. Assuming a growth rate of 0.1 percent per year (low compared to growth rates of energy after the industrial revolution), k = ln(1.0 + 0.001) = 0.0009995, and b = ln(9.995e-4*(1e11+1))/9.995e-4 = 18429 years, which is only about four times longer than human recorded history, or definately less than all energy earth's inhabitants will ever need. Jrincayc 12:40, 18 May 2006 (UTC)

[edit] Controlling the birth rate

Well said! (see above: Exponetial index formula) Very well said and well illustrated.

This is exactly the point. Unless humanity is willing to stabilize its birth rate which means there has to at some point be ZERO population growth - then humanity is doomed! None of the world's problems have a solution while people think they can have x number of kids where x is a number much greater than 2.

[edit] Swipe at Skeptical Environmentalist

User:User:24.253.113.115 wrote: Swipe at Skeptical Environmentalist exemplifies deficiencies of the Limits to Growth approach.

What Limits to Growth actually has is the above table which has the current reserves for oil running out in 1992 assuming constant exponential growth.

Divorced from context, the above statement is misleading. The book very clearly predicted that we would start running out of resources in the 1980s, 1990s, and later unless we implemented radical changes to our economy and polity in the 1970s (changes of a magnitude that, as a practical matter, would have required central coercion and would have given people such as the authors inordinate power in shaping society).

The truth of the above quotation is central to the weakness of the book; the authors assumed constant exponential growth in consumption and arbitrarily decided that everything else (productivity, technology, replenishment) would remain relatively fixed. In essence, the authors chose parameters that guaranteed the desired outcomes but had little relationship to reality (the pace of evolution in the decades preceding publication suggested anything but a sudden halt).

Limits to Growth was a pseudo-scientific attempt to justify a radical environmental ideology. It was wrong and has negligible value. Such irresponsible work undermines legitimate efforts to improve the earth.

[1] Writing for the Michigan Law Review, Alex Kozinski discussed Limits to Growth at length at the beginning of his heavily sourced, comprehensive review of The Skeptical Environmentalist. Lomborg earned the enmity of the environmentalists because he demonstrated the manner in which many leading environmentalists manipulate statistics to bolster political agendas.

I was unable to find justification of the claim that: The book very clearly predicted that we would start running out of resources in the 1980s, 1990s, and later unless we implemented radical changes to our economy and polity in the 1970s. The 'standard run' chart figure 35 for example shows the industrial output collapse begining at around 2010. On page 66, Limits to Growth states: Given present resource consumption rates and the projected increse in these rates, the great majority of the currently important nonrenewable resources will be extremely costly 100 years from now. That would be in 2072. If you actually look at the growth rates of for example petroleum consumption from 1960 to 1970 [2], the growth rate is exponential at 7.9% (higher than the 3.9% figure that Limits to Growth uses). The primary reason that there was no collapse of oil was because of OPEC raising prices dramatically, instead of hitting a geological limit. Lomberg clearly claims that Limits to Growth states that we will run out of oil in 1992, but the reference is to the table of exponential indexs. This table does not say that we run out of oil in 1992. I can certainly believe that the book implies that we will start noticing running low of resources in the 1980s, but I question the statement that it very clearly does. If it very clearly does, than please enlighten me as to where? Thank you. Jrincayc 23:18, 6 Feb 2005 (UTC)

From its very title to its overall tone to its dire warnings, LTG strongly implies that the rundowns would begin in the near then-future--as you note. From the intensity of their implications, I think the inference that their implications rise to the level of predictions is reasonable.

Of course, the authors were surely aware that use of mere strong implication and qualifying language would allow them to straddle their quasi-predictions and abandon them without acknowledging how totally wrong they were--just as this technique would have allowed them to claim vindication had history proven them correct.

Inferences are interpretations, so by definition the book does not necessarily have to state expressly what I inferred. However, publishing a tract full of alarmist pseudo-science and then hiding behind qualifiers stinks of intellectual cowardice (citing OPEC is all fine and well, but it reminds us that LTG didn't take adaptation, market mechanisms, technology, etc. sufficiently into account, calling the entire premise of the LTG model's utility into question). To me, the thrust of their implications amounted to very clear predictions, but that might take the interpreting dangerously far.

So, I concede that "predicted," or "arguably predicted," or "very strongly implied" might have been better choices than "very clearly predicted;" and your agreement on "implies" is certainly defensible. Nevertheless, my mildly imprecise wording warranted rebuttal and not exile from the main page; my interpretation of LTG is a valid counterpoint. User:Chrisa798

I have no significant objection to you working on the phrasing and content of the article. And for what it's worth, I did not remove you text (I thought I was too biased to safely do so.). I certainly agree that the World3 model fails to take into account market mechanisms. I do wonder what would have happened if OPEC had not caused high prices in 1979, and instead the natural causes had caused an oil shortage in the 1990s. Meadows et al explicitly state that their model does not take into account political events, so I think OPEC is a fair reason for their ideas to fail. I encourage you to find examples of quotes where they are implying sudden collapse, or if that is difficult, find examples of contemporary (1970s) interpetations to that effect. I think those would be interesting and useful additions to the article. Thank you. Jrincayc 03:36, 25 Feb 2005 (UTC)
To quote from a Mobil add that appeared in the Oct 22, 1973 Time magazine, page 1, Vol 102, No. 17: "It takes nature millions of years to create an oil field. It takes man only 20 or 30 years to use it up. ¶ Some day, all the wells in the United Statse will run dry and die. We're sorry to have to tell you that most on land are past their prime. ¶ Fortunately, there is more oil to be found. Some will be discovered on land; but the really promising areas are at sea." I think that this is rather strong evidence that oil shortages are being noticed. Jrincayc 16:15, 20 Mar 2005 (UTC)

[edit] Price Effects

User:129.174.176.4 added the following:

In addition, several economists believe that the books is false because it leaves out a key factor: price. If prices rise, consumers will conserve, and producers will produce more or substitutes will be found.
However, several people, including Julian Lincoln Simon, believe that as long as the human mind is free (Simon's "Ultimate Resource", this will not be a problem.

which was removed by User:Sunray with the comment: rv - actually the authors did discuss price and its effects; best you find a source for this and quote it

The authors of Limits to Growth do discuss price and its effects in Beyond the Limits and the 30 year update and possibly in the original book, but the world3 model is seriously lacking in some important price feedback effects. For example, the natural resources model allows the price to increase by a factor of 80 without any direct effect on resource use, instead the only effect is on the amount spent on obtaining the resources. The resource use is then decreased when the economy collapses, but this is a rather late effect. The book Models of Doom best describes this. Jrincayc 16:25, 6 November 2005 (UTC)

The effects of price are discussed in Limits To Growth, but only fleetingly. --crafty bison

[edit] Removed LaRouche

Removed:

Another harsh critic of Limits to Growth was Lyndon LaRouche, who authored a 1983 book There Are No Limits to Growth and included the Club of Rome prominently in his view of a global Malthusian conspiracy. [3]

LaRouche's views are not significant to anybody except LaRouche and his tiny band of followers. --Robert Merkel 05:33, 5 May 2006 (UTC)

[edit] Sentence about the "point" of the book

I removed the following from the text:

Nevertheless, many today think that the overall message was accurate: the resources of the Earth are finite and are thus, inevitably, subject to natural limits.[4]

I think this sentence is pretty content-free. The authors made specific, dire predictions, which, as we know, did not come to pass in any way, shape or form. The authors did not assert, "Hey, these things are finite. They're going to run out some day in the indeterminate future". They claimed these resources were going to run out and gave dates. I think it's pretty clear from even the most cursory observer that their modelling was wrong.

It is not clear at all that their modeling was wrong, actually, and nobody has been able to cite a reference in the original work where they gave the dates you describe. Some critics have taken data or quotes out of context to try and make this point, but the original text makes no such claims.Ericy (talk) 13:11, 11 March 2008 (UTC)

Now, this quote says that they were essentially right because of a fact which has nothing to do with their assertion, and is trivial besides. Of course resources are finite, noone argues this. The argument is how much of it we have. And it is clear that these authors had some serious problems in their modelling. (And, hey, I should know. I just gave a final in my Intro to Math Modelling course. w00t)

Well as you say, from this point one can conclude that the resources will run out at some point in the indeterminate future, and hence there really are limits to growth. The only point open for debate then is roughly how long will it be before we reach these limits.Ericy (talk) 13:11, 11 March 2008 (UTC)

Seriously, the sentence I removed is analogous to something like someone predicting "The Chicago Cubs will win the World Series in 2006," and when they don't, an apologist coming along and saying "Well, the commentators overall message was accurate: it stands to reason that if baseball is played long enough, the Cubs will win the World Series at some point." --Deville (Talk) 04:04, 9 May 2006 (UTC)

(Off topic discussion moved to new section Predictions)
Followup: we're also getting a bit far afield here anyway. This section originally started when I mentioned that that earlier sentence was useless. Do you agree?--Deville (Talk) 13:06, 11 May 2006 (UTC)
I think that the earlier sentence is at minimum badly written, and taking it out is acceptable. Jrincayc 12:25, 12 May 2006 (UTC)

[edit] Predictions

I will send $5 US to the first person who can show me a definative and non-trivial prediction that the authors made in the book Limits to Growth and that has not come true. I reserve the right to choose what I consider definative and not coming true, but this should be easy to pass if there really are specific and dire predictions that should have happened already in Limits to Growth. Put the page number, the prediction, and evidence that it did not come true in a comment below. Good luck. Jrincayc 12:32, 9 May 2006 (UTC)

Try "the world population will be 7 billion in 2000". PayPal to my address, please. --crafty bison
Hmmm, let's see:
  • "there will be a desperate arable land shortage before the year 2000"
  • we will run short of gold by 1979
  • we will run short of silver by 1983
  • we will run short of tin by 1985
  • we will run short of zinc by 1989
  • we will run short of mercury by 1990
  • we will run short of petroleum by 1990
  • we will run short of natural gas by 1992
Except for petroleum, all these commodities are markedly cheaper than they were when the book was written. And the recent price spike in petroleum quite probably has more to do with geopolitics than supply, but, hey, I'll give that to you. That's seven predictions which are flatly wrong, do you own me $35?  :)
Seriously, predictions like this are wrong all the time. People use models they like, and sometimes these models work, and sometimes they don't. This is ubiquitous in science, and especially so in such a complex and (at the time) new field of environemental science. The science is a lot better now, although admittedly it still has a lot of problems. But in any case the world didn't end in the mid-90s.
And, for what it's worth, even the sentence I removed conceded that few, if any, of their predictions came true, but then claimed that this was alleviated by the fact that they claimed something was finite, and of course it is finite, so they were in some sense "right". --Deville (Talk) 13:43, 9 May 2006 (UTC)
Well, since you didn't provide page numbers, I am assuming that these are the 'predictions' you are refering to:
  • there will be a desperate arable land shortage before the year 2000. Full quote page 51. "Figure 10 shows that, even with the optimistic assumption that all possible land is utilized, there will still be a desperate land shortage before the year 2000 if per capita land requirements and population growth rates remain as they are today." This is a conditional prediction based on per capita land requirements and population growth rates staying constant, therefore, as I read it, there is no specific dire prediction here because the two conditions failed.
  • we will run short of gold by 1979, we will run short of silver by 1983 ... You are probably refering to the "Exponential Index" of reserves that appear on pages 56-59. As the Limits to Growth article already discusses this is again a conditional prediction depending on no new reserves being found and on continued exponential growth.
So, I don't consider anything that you have put to be specific predictions. As User:Chrisa798 stated earlier in this discussion: "Of course, the authors were surely aware that use of mere strong implication and qualifying language would allow them to straddle their quasi-predictions and abandon them without acknowledging how totally wrong they were--just as this technique would have allowed them to claim vindication had history proven them correct." I don't think that the authors of Limits to Growth are completely correct by any means. In particular, the Non-renewable resources model in world3 should be taken out and shot. However, I have not found any non-trivial, definitive prediction that is in Limits to Growth that would have come true or false by now. Good luck in finding them. I look forward to seeing what you come up with. Jrincayc 02:07, 10 May 2006 (UTC)
Ok, fair enough. What you're saying, then, is that the book makes no predictions at all? If yes, what predictions did it make? --Deville (Talk) 13:01, 11 May 2006 (UTC)
Well, I am reading over the book looking for predictions, and so far I have seen dire quoted predictions, but not a single unconditional prediction. Most of the predictions are partially irrelevent now because they have the condition of continued exponential growth at approximately the same rates. However, the growth rates of population and resource consumption have decreased quite a bit from what they were in the 1960s (at the cost of a recession or two, a couple civil wars, a new disease, and quite a bit of intentionial lowering of consumtion and population growth). So, I am looking for predictions, and my $5 offer still stands. I will make a comment here when I finish the book. Jrincayc 12:25, 12 May 2006 (UTC)
I finished reading Limits to Growth. Here are two predictions in it: "Given present consumtion rates and the projected increase in these rates, the great majority of the currently important nonrenewable resources will be extremely costly 100 years from now." (page 66 LTG). "We can thus say with some confidence that, under the assumption of no major change in the present system, population and industrial growth will certainly stop within the next century at the latest." (page 126 LTG). The only really define predictions that don't have loads of qualifiers are quite a bit in the future (as in the 2070 or so range). So, yes, there are some predictions, but most of them will not be tested for awhile. I think that the 2.2 percent population growth of the 1970 was definitely not sustainable for very long, and I don't think the current oneish percent is very sustainable for very long either. I think I was rather disappointed in how little the ideas have changed between Limits to Growth and Limits to Growth, the 30 year update. For example, where is the hard consideration as to what really slowwed the 2.2 percent population growth, and the 6% (in US) growth of use of oil? Where is the thoughtful examination of how the model actually implements nonrenewable resources. Back, to the previous question, I was unable to find any predictions that have been proven false. It would still be interesting to find them. Jrincayc 14:43, 14 May 2006 (UTC)
There is a reason that they updated the text - first in 1992, and then again in 2002. Mainly to compare and see how well their scenarios hold up, and also to re-run the computer model with the latest data. I should also add that the authors don't claim that their work is in any way prediction - they are scenarios. They run a number of different scenarios with differing assumptions, and by comparing the results, they can conclude that some ranges of futures are unrealistic, and other futures are more likely. In the preface to the 2004 book, they state that they will once again update in the year 2012, when they expect that there will be "abundant data to test the reality of overshoot".Ericy (talk) 12:22, 11 March 2008 (UTC)
So, I guess what you're saying is, not only were they not right, they weren't even wrong? --Deville (Talk) 22:48, 14 May 2006 (UTC)
I think the agricultural model they used in World3 might be right. The nonrenewable resource model is mostly wrong. Population, sorta right. I think they are more right then their detractors admit and less right then they think they are. I personally am eagerly awaiting the world4 model. So, yes, they are not right, and they are not wrong, but somewhere in the middle (and you put that wonderfully). Jrincayc 01:57, 16 May 2006 (UTC)

[edit] The corect title is "The Limits to Growth"

The title of the 1972 book began with the word "The". The 2004 update did not.

A proper fix to this would include renaming the article, and providing redirection for the old title, because other articles link to it.

[edit] 2 vs 5 for factor of reserves

In the criticism section, there is some confusion over which factor was being used. For individual materials, they used both the actual reserve values and a factor of 5. For the overall amount of resources (where they aggregate everything into one lump) they use both a factor of 1 and a factor of 2 (and in Dynamics of Growth in a Finite World I think they also use a factor of 10). So if you are talking about individual resources, it is 5, and if you are talking about total resources it is 2. The section could be more clear about that. Jrincayc (talk) 13:38, 18 February 2008 (UTC)

Total resources seems more relevant where this discussed in the article.Ultramarine (talk) 14:19, 18 February 2008 (UTC)

[edit] removed

removed this quote from Exponential Reserve index for inaaccuracy:

For petroleum, neither assumption was correct in the years that followed due to the OPEC's oil embargo, followed by a return to increasing production.

Oil is still finite, as opposed to the view espoused by the author, and in addition the world has since reverted to an "undulating plateau" period, not growth. ays (talk) 16:55, 30 April 2008 (UTC)

Okay. I agree that oil is finite. What I was trying to say when I wrote that was that oil production was not increasing at an exponential rate, and neither was it constant. Do you agree with that statement? Jrincayc (talk) 12:36, 1 May 2008 (UTC)
Yeah, that's significantly better - the earlier sentence is just misleading because it sends out the notion that production has increased constantly since that period, which is just false. I appreciate the work you've put into the article, though. ays (talk) 05:56, 3 May 2008 (UTC)