Friday, September 30, 2011

The renewable revolution

Worldwide growth of Photovoltaic and Wind installed power, by Emilio Martines. Data from IEA Photovoltaic Power Systems Programme, European Wind Energy Association and Earth Policy Institute.

For a change, here is a non-Cassandric post. Look at the data in the figure above, kindly provided by Emilio Martines, member of ASPO-Italy. The growth of photovoltaic and wind energy has been impressively fast during the past 2-3 decades. The log scale evidences the exponential growth of both technologies. There are no signs of slowdown, so far, despite recessions and the bad state of the economy. According to the graph, wind power grows of a factor 10 in less than 10 years, PV power takes little more than 5 years. At these rates, both wind and PC could reach the goal of one installed terawatt (TW) each around 2020.

Of course, the capacity factor of wind and PV is smaller than that of conventional sources, so that one TW of renewable power can produce considerably less energy than one TW of - say - a coal fired plant. Then, there is the question of storage and other issues. Nevertheless, the data are impressive, considering that the total electric power installed in the world today is around 2 TW. It is exactly the value of renewable peak power that we could reach by the end of the current decade. Are we seeing a glimpse of light at the end of the tunnel?

Obviously, nothing can grow exponentially forever. But we have nevertheless generated an energy revolution: renewable power has a market and it grows. It is a revolution that can't be stopped any more. It gives us a chance to replace fossil fuels before it is too late. It is a fighting chance, but we have it.

Wednesday, September 28, 2011

Laughing with neutrinos

Faster-than-light neutrinos and the subsequent terrible mishap of the Italian minister for science and education (Ms. Gelmini) are a bit off-topic for the Cassandra blog, except as a way to highlight the condition of terminal incompetency of the structures that should lead us out of the present crisis. Anyway, I guess we might as well get a good laugh out of this story, in particular about the minister's statement that there should exist a 730 km long tunnel from Geneva to Central Italy. So here are a few jokes translated from Italian and readapted, mainly from the blog "Spinoza". (image above from "CronacaLive")

Every day, in Geneva, a neutrino wakes up and he knows that he will have to run faster than a photon in a 730 km tunnel in order to overcome it.
Every day, in Geneva, a photon wakes up and he knows that he will have to run in a 730 km tunnel fast enough not to be overcome by a neutrino.
Whether you are a neutrino or a photon, it doesn't matter. Just be sure not to be Gelmini.

Minister Gelmini confirms: neutrinos rode unicorns while in the tunnel.

Neutrinos found to have mass; larger than that of Gelmini's neurons.

Einstein was wrong on relativity, but his theory on stupidity is confirmed.

Einstein proven wrong: God wins big in Montecarlo.

The bartender says, "we don't serve neutrinos here"
A neutrino enters in a bar.

Today Schroedinger's cat will be buried. There will follow its death, tomorrow.

CERN's press release: "light than faster are neutrinos"

Superman to Lois Lane: "and you were complaining that I was faster than a bullet!"

To scientists: if you are going to rewrite physics, could you please do it without all those equations?

Press release from the Zeno Institute of Philosophical Research: "Neutrinos may be faster than light, but they will never be able to overcome the turtle, anyay"

From Switzerland to Italy, neutrinos go faster than light. On the way back, they are stopped by the usual traffic jams.

In Italy, not even neutrinos respect the speed limit.

Saturday, September 24, 2011

The minister and the neutrino

Above: Ms. Mariastella Gelmini, Italian minister of Education and Scientific Research,  shown as "Our Lady of Ignorance" in a picture that appeared on the Italian daily "La Repubblica"

You may not believe it, but what follows is an official press release of the Italian Ministry of Public Education and Scientific Research. It refers to the recent statements of the CERN about the speed of Neutrinos and it is signed by the minister, Ms. Mariastella Gelmini.

I leave it without comments, except to note, for those of you who may not be familiar with Italian geography, that the tunnel mentioned in the statement and that is supposed to go from CERN (Switzerland) to the Gran Sasso Laboratory (central Italy) should be at least 750 km long, if it existed. But this is far from being the worst thing in the document from the ministry.

You may have a good laugh at this press release, but it is also something worrisome. I am afraid that such a level of idiocy pervading public institutions may not be limited to Italy, there are other examples elsewhere, perhaps worse. Something is deeply wrong, here.....

Note added after posting: from the comments received, I think that many people have missed the point of this press release. It is true that the minister made herself ridiculous by claiming the existence of a 750 km long tunnel from Switzerland to Central Italy. But from the viewpoint of a politician, that's nothing of any importance. Their job is not to be approved by scientists; their job is to obtain and keep power, and for this purpose they must appease the lobbies that keep them in power. So, Ms. Gelmini didn't care about how long tunnels are or even if tunnels exist. She cares about something completely different.

Consider the sentence: "this event .. will change the face of modern physics. Exceeding the speed of light is an epochal victory for scientific research around the world." This and the general tone of the press release is the key of the whole story. The minister is saying that the physics we know is all wrong and should be revoluzionized. Why so much enthusiasm about a revolution in physics? Is the minister planning to build a fleet of faster-than-light interstellar spaceships? No, the minister is happy that relativity, a cornerstone of modern physics, has been demonstrated to be wrong (at least in her opinion). And, if relativity is wrong, so could be climate science and many other areas of science that are bothering some powerful lobbies. You see, it is politics, it is a job, a trade and a vocation.


(English translation from Rangle).

The Minister and the Neutrino

Statement by the Minister Mariastella Gelmini (Rome, 23 sep 2011) 
"The CERN and National Institute for Nuclear Physics discovery is a scientific event of fundamental importance."
“I extend my approval and my sincerest congratulations to the authors of a historical experiment. I am deeply grateful to all the Italian researchers who contributed to this event that will change the face of modern physics. 
Exceeding the speed of light is an epochal victory for scientific research around the world. 
Italy has contributed to the construction of the tunnel between CERN and Gran Sasso Laboratories, through which the experiment took place, with a sum now estimated at around 45 million euros. 
In addition, today Italy supports the CERN with absolute conviction, with a contribution of more than 80 million euros per year and the events we are experiencing are confirming that it is a good and far-sighted choice".

Thursday, September 22, 2011

Staring at the cave bear straight in the eyes. Mass movements and decision taking in modern society

Decision taking is not an easy task, unless you are forced by finding yourself staring at a cave bear in the eyes. That must be the reason why we are not eacting to major threats such as peak oil and global warming.

Years ago, when I was a student, a fire broke out in the chemistry lab. I was the first to rush to the fire extinguisher and I managed to put out the fire. I was surprised myself at what I did; normally, I am not the kind of guy who takes split-second decisions. I am more one of those people who see the menu of a Chinese restaurant as a minor drama in life. But in that occasion, when facing the fire in the lab, I didn't think, I acted. I still remember the curious sensation of watching myself as I was running at full speed toward the flames, fire extinguisher in hand, no hesitations involved.

Maybe you have had similar experiences, situations in which you don't think about what to do; you do it and, perhaps, you are surprised to be looking at yourself doing it. It must be the same mechanism that worked when our ancestors found themselves staring at a cave bear straight in the eyes. Run or fight, there would be no time to scratch one's head. There has to be something deep inside our minds that has evolved over millions of years and that makes us react fast to emergency situations.

But emergencies are not something just for individuals; there are worldwide emergencies that demand some kind of action at the societal level. Peak oil and global warming are among the most important ones. So far, however, it seems that we haven't realized that the cave bear is here. Just like single minds, society normally works as a tangle of feedbacks that work to keep things as they are. When new data challenge the prevalent world view; these mechanisms act in order to accommodate the new data without changing the existing view. That may involve downplaying the relevance of the data or ignoring them or, in extreme cases, aggressively demonizing those who propose them. It is called "blame the messenger". As long as a true emergency is not perceived, the result is inaction.

These effects have been around for a long time, but today they are greatly amplified by the Web. People tend to see the world more and more through information filters that they themselves create, seeking information from sources that confirm their ideas. And that is not just a conscious process: the search engine you use knows what are your preferences and will make sure that what you find conforms to your personal world view. These effects combined are called at times "Internet Bias." The filters that you choose (and that you do not choose) are keeping you safely embedded in your comfortable cocoon of facts and interpretations and you may not even realize that these filters exist. If you are a believer of hyper-abundant abiotic oil or if you are sure that climate change is a hoax created by evil scientists in order to stock up with fat research grants; then you can always enjoy the company of like-minded people on the web and, together, you'll keep reinforcing each other's beliefs.

One consequence is that the very concept of "debate" is disappearing. Debates are possible when the two sides debating at least agree on facts. But the Internet bias makes sure that each side has their own facts. Look at how the (so called) debate on anthropogenic global warming is conducted. The debate on peak oil is somewhat more civilized, but even there each side has their own facts. And if the debate leads to nowhere, no decision can be taken on how to solve the problems. Indeed, we are not taking any.

It is often said that a major catastrophe would stir society into action. That hasn't occurred, so far, but it may well be that in the future we'll face something so enormous and so disastrous that we won't be able to ignore it and forget it so fast. We will be staring at the cave bear into the eyes. What will we do?

It may well be that societies have mechanisms equivalent to those of a single mind to react to emergencies. One such mechanism involves the creation of what we call a "mass movement," a tool to create change by sidestepping the tangle of negative feedbacks that keep society static. It is the equivalent at the societal level of the "cave bear reaction" at the individual level.  Political mass movements have been dominating politics during the first half of the 20th century: Nazism, fascism, communism. Eric Hoffer wrote a fascinating account of how these movements work in his 1951 book "The True Believer". Hoffer argues that all mass movements share the same characteristics and arise from similar conditions, the main one is an old order that is completely discredited and that needs to be replaced. We surely are well stocked everywhere in terms of discredited old orders. So, can we expect to see mass movements rising again?

Some people advocate the idea of a Green mass movement under the name of "deep green resistance". So far, this idea doesn't seem to have been successful. In large part it has to do with some of the specific characteristics of Green ideas. As Hoffer says in his book, mass movements usually aggregate against something rather than for something. On this point, it is illuminating to read a note in Hoffer's book; when he reports how a Japanese delegation visited Germany in the 1930s to study the Nazi propaganda methods. When asked their opinion on what they saw; the Japanese answered "It is absolutely wonderful what the Germans have done; unfortunately we cannot do the same in Japan because we haven't got any Jews".  Now, think about the iconic slogan of the Greens, "Nuclear? No thanks". It was so successful because it hints at an enemy, nuclear energy. But it does so in such a gentle and polite way! Compare it with the Nazi slogans against the Jews and you'll see the difference.

That doesn't mean that people are not trying to use the hate trick to gain followers. They are, and what we are seeing now is more like an "anti-Green" movement taking shape, focused on hating everything "ecological". It behaves very much according to what Hoffer says are the typical characteristics of these movements, for instance targeting "enemies of the people" in the form of scientists.  However, not even Anti-Green ideas seem to be able to gain the status of a full fledged mass movement.

That we are not reacting to the crisis with mass movements is a good thing. The record these movements is very poor in terms of successful carrying out their ideological goals, besides generating all sorts of nasty side effects, from mass murder to political oppression. If you think of how successful was Soviet Communism in creating a proletarian paradise on earth, you may shiver at the idea of how successful the Greens could be in creating an ecological paradise on our planet. As Hoffer discusses in his book, mass movements are impossible to control, even by those who have created them.

But, then, what do we do? Can we only wait and do nothing until some really huge catastrophe stirs us into taking some kind of action, which will probably be the wrong one? I think not; we can do better than limiting our choices to the binary couple of complacency and panic. After all, I am sure that our paleolithic ancestors had a much more nuanced way to react to the presence of cave bears than simply madly attacking and running away at full speed. The same is true for us at the societal level.

In general, the choices you have depend on what you know. And that depends on the way you obtain information. Think about that: mass movements were the logical consequence of the poor and unstructured information that was provided by the mass media of the first half of the 20th century. Often government controlled, these mass media didn't provide a range of choices; just the party line. With such limited information, it is no wonder that people aggregated in masses of individuals who saw the world in the same terms.

Now, think of the situation today. People have an enormous larger range of information. It is a trend that started with a larger availability of printed material, but the Internet has been a true information explosion. But even with so much information, there is a problem. This is information is not structured. It is an inchoate mass of data out of which every one of us is trying to make sense, mainly by using search engines. But search engines are still primitive. We tend to see Google as a great and advanced tool, but think how hard its task is: indexing the trillions of pages of the Internet. What Google does is to list first the most clicked sites, but that is far from being the way to find what you are looking for. There is no guarantee that what you find first in the list is relevant or that it has any connection with reality. With the additional feature of personalized search, the way Google indexes the Internet is guaranteed to favor the creation of impermeable bubbles of knowledge which are incompatible with each other. The result is the political sectarism that has replaced mass movements almost everywhere.

But think that Google is just a little older than 10 years. Search engines are evolving rapidly and the ways they work today will be obsolete soon. What we need is structuring the Web in such a way that searches will be more likely to return  high quality information rather than poor quality information. So far, this kind of structuring doesn't exist; just think how the best quality information we have, peer reviewed scientific journals, exist mainly behind paywalls and as a consequence are not available for decision makers (it is equivalent to shooting yourself in the foot when facing a cave bear). Right now any search that is meant to return useful and validated data is nearly impossible using conventional search engines. So, there is clearly a need to do better and it is likely that some form of hierarchical strucutration of the information available on the Web will emerge. That doesn't mean that anyone will be shut off from the Web. It is only that good work will be rewarded and sloppy work will be punished (just as the tricks called SEO - search engine optimization). With a better structuration of the Web, we have a chance to move towards a different structuration of the decision making process. That can lead us out of the present decisional impasse without the need of generating those inflexible and dangerous methods known as mass movements. It may take time, but it is probably the best hope we have.

Sometimes  when I speak in public, I ask to the audience when it was that they took a major decision in their life and how they arrived to it. I often notice that it is a soul-searching moment. Taking decisions is not easy for us at the individual level, just as it is not at the societal level. What comes out of the discussion is that decisions taken as a result of the cave bear reflex are just as bad as non-decisions, that is waiting too long before deciding. The best way to take decisions is to be informed and to have choices. Nobody can predict the future but we can always be prepared for it.

Hat tip to Arthur Berman for suggesting to me the book "The True Believer" by Eric Hoffmann

Thursday, September 15, 2011

Cassandra's curse: how "The Limits to Growth" was demonized

As part of a mini-series on "The Limits to Growth" (earlier posts here, here, and here), I am reprinting (with some minor modifications) a post that I published on "The Oil Drum" in March 2008. Above: image from the 1972 Report. 

In 1972, "The Limits to Growth" study arrived in a world that had known more than two decades of unabated growth after the end of the Second World War. It was a time of optimism and faith in technological progress that, perhaps, had never been so strong in the history of humankind. With nuclear power on the rise, with no hint of scarcity of mineral resources, with population growing fast, it seemed that the limits to growth, if such a thing existed, were so far away in the future that there was no reason to worry. And, even if these limits were closer than generally believed, didn't we have technology to save us? If we could reach the Moon, as we did, in 1969, what was the problem with such trifles as resource depletion and pollution? The future could only be shiny for ever and ever.

Against that general feeling, the results of "The Limits to Growth" showed that the future was not to be shiny at all. The authors had developed a model that could keep track of a large number of variables and of their interactions as the system changed with time. They found that the world's economy tended to collapse at some time in the 21st century. The collapse was caused by a combination of resource depletion, overpopulation, and growing pollution (this last element we would see today as related to global warming). Only specific measures aimed a curbing growth and limit population could avoid collapse.

There is a legend lingering around the first "Limits" book that says that it was laughed off as an obvious quackery immediately after it was published. It is not true. The study was debated and criticized, as it is normal for a new theory or idea. But it raised enormous interest and millions of copies were sold. Evidently, despite the general optimism of the time, the study had given visibility to a feeling that wasn't often expressed but that was in everybody's minds. Can we really grow forever? And if we can't, for how long can growth last? The study provided an answer to these questions; not a pleasant one, but an answer nevertheless.

The Limits to Growth study had everything that was needed to become a major advance in science. It came from a prestigious institution, the MIT; it was sponsored by a group of brilliant and influential intellectuals, the Club of Rome; it used the most modern and advanced computation techniques and, finally, the events that were taking place a few years after publication, the great oil crisis of the 1970s, seemed to confirm the vision of the authors. Yet, the study failed to generate further research and, a couple of decades after the publication, the general opinion about it had completely changed. Far from being considered the scientific revolution of the century, in the 1990s The Limits to Growth had become everyone's laughing stock: little more than the rumination of a group of eccentric (and probably slightly feebleminded) professors who had really thought that the end of the world was near. In short, Chicken Little with a computer.

The reversal of fortunes of "The Limits to Growth" was gradual and involved a debate that lasted for decades. At first, critics reacted with little more than a series of statements of disbelief. Just a few early papers carried a more in-depth criticism, notably by William Nordhaus (1973) and by a group of researchers of the University of Sussex that went under the name of the "Sussex Group" (Cole 1973). Both studies raised a number of interesting points but failed in their attempt of demonstrating that the Limits study was flawed in its basic assumptions. In addition, already these early papers showed an acrimonious streak that became common in the debate from the side of the critics. Political criticism, personal attacks and insults, as well as breaks of the basic rules of the scientific debate. For instance, the editor of the journal that had published Nordhaus' 1973 paper refused to publish a rebuttal.

With time, the debate on the Limits book veered more and more on the political side. In 1997, the Italian economist Giorgio Nebbia noted that the reaction against the study had arrived from at least four different fronts. One was from those who saw the book as a threat to the growth of their businesses and industries. A second was that of professional economists, who saw it as a threat to their dominance in advising on economic matters. The Catholic Church provided further ammunition for the critics, being piqued at the suggestion that overpopulation was one of the major causes of the problems. Then, the political left in the Western World saw the study as a scam of the ruling class, designed to trick workers into believing that the proletarian paradise was not a practical goal. And this is a clearly incomplete list; forgetting the political right, the believers in infinite growth, politicians seeking for easy solutions to all problems, and many others. All together, these groups formed a formidable coalition that guaranteed a strong reaction against the Limits to Growth study. This reaction eventually succeeded in demolishing the study in the eyes of the majority of the public and of specialists at the same time.

The fall of the Limits to Growth was greatly helped by a factor that initially had bolstered its credibility: the world oil crisis of the 1970s. The crisis peaked in 1979 but, in the years that followed, new oil resources started flowing abundantly from the North Sea and from Saudi Arabia. With oil prices plummeting down, it seemed to many that the crisis had been nothing but a scam; the failed attempt of a group of fanatic sheikhs to dominate the world using oil as a weapon. Oil, it seemed, was, and had always been, plentiful and was destined to remain so forever. With the collapse of the Soviet Union in 1991 and the "New Economy" appearing, all worries for the future seemed to be over. History had ended and all we needed to do was to relax and enjoy the fruits that our science and our technology would provide for us.

At this point, a perverse effect started to act on people's minds. In the late 1980s, all that people could remember of the Limits to Growth book, published almost two decades before, was that it had predicted some kind of catastrophe at some moment in the future. If the world oil crisis had been that catastrophe, as it had seemed to many, the fact that it was over was the refutation of the same prediction. This factor had a major effect on people's perception.

The change in attitudes was gradual and spanned a number of years but we can probably locate a specific date for the actual turning point. It happened in 1989 when Ronald Bailey, science editor of the Forbes magazine, published a sneering attack against Jay Forrester, the father of system dynamics, the method behind the Limits study  (Bailey 1989). The attack was also directed against Limits book which Bailey said was, “as wrong-headed as it is possible to be”.

To prove his point Bailey revived an observation that had already been made in 1972 by a group of economists on the "New York Times" (Passel 1972). Bailey said that:
“Limits to Growth” predicted that at 1972 rates of growth the world would run out of gold by 1981, mercury by 1985, tin by 1987, zinc by 1990, petroleum by 1992, copper, lead and natural gas by 1993.
In 1993 Bailey reiterated his accusations in the book titled “Ecoscam.” This time, he could state that none of the predictions of the 1972 Limits study had turned out to be correct.

Of course, Bailey’s accusations are just plain wrong, being based on data taken out of context. In table 4 of the second chapter of the book, we can find a row of data (column 2) for the duration, expressed in years, of some mineral resources in the assumption of continuing exponential growth. Bailey had presented these data as the only "predictions" that the study had made and he had based his criticism on that, totally ignoring the rest of the book.

Reducing a book of more than a hundred pages to a few numbers is not the only fault of Bailey's criticism. The fact is that none of the numbers he had selected was a prediction and nowhere in the book it was stated that these numbers were supposed to be read as such. Table 4 was there only to illustrate the effect of a hypothesis, that of continued exponential growth of the exploitation of mineral resources. Even without bothering to read the whole book, the text of chapter 2 clearly stated that this continued exponential growth was not possible. The rest of the book, then, showed various scenarios of economic collapse that in no case took place before the first decades of 21st century.

It would have taken little effort to debunk Bailey's claims. But it seemed that, despite the millions of copies sold, all the "Limits to Growth" books had ended in the garbage bin. Bailey's criticism had success and it started behaving with all the characteristics of what we call today “urban legends."

We all know how persistent urban legends can be, no matter how silly they are. At the time of Bailey's article and book, the Internet as we know it didn't exist yet, but word of mouth and the press were sufficient to spread and multiply the story of the "wrong predictions." Just to give an example, let's see how Bailey's text even reached the serious scientific literature. In 1993, William Nordhaus published a paper titled “Lethal Models” which was meant as an answer to the second version of the "Limits", published in 1992 with the title "Beyond the Limits".

Nordhaus' paper was accompanied by a series of texts by various authors grouped under the title of “Comments and Discussion” and in this section we find a short text by Robert Stavins, an economist from Harvard University, where we can read that:
If we check today to see how the Limits I predictions have turned out, we learn that (according to their estimates) gold, silver, mercury, zinc, and lead should be thoroughly exhausted, with natural gas running out within the next eight years. Of course, this has not happened.
All this is, obviously, is taken straight from Bailey's paper in "Forbes". Apparently, Stavins had forgotten that it is the duty of a serious scientist to check the reliability of the sources that he or she cites.

Unfortunately, with this paper by Nordhaus the legend of the “wrong predictions” was even enshrined in a serious academic journal. With the 1990s, and in particular with the development of the Internet, the dam gave way and a true flood of criticism swamped the book and its authors. One after the other, scientists, journalists, and whoever felt entitled to discuss the subject, started repeating the same line over and over: the "Limits to Growth" study had predicted a catastrophe that failed to occur and therefore the whole idea was wrong.

After a while, the concept of “wrong predictions” became so widespread that it wasn’t any more necessary to state in detail what these wrong predictions were and why they had been so wrong. The criticism could also become weird, such as when the authors were accused of being part of a conspiracy designed to create "a kind of fanatic military dictatorship" (Gloub and Townsend, 1977) or aggressive, such as when someone declared that the authors of the book should be killed, cut to pieces, and their organs sent to organ banks. Today, we can find Bailey's legend repeated on the Internet literally thousands of times in various forms. Sometimes it is exactly the same text, cut and pasted as it is; in others, it is just slightly modified.

At this point, we may ask ourselves if this wave of slander had arisen by itself, as the result of the normal mechanism of urban legends, or if it had been masterminded by someone. Can we think of a conspiracy organized against the authors of the Limits book or against their sponsors, the Club of Rome? On this point we can find an analogy with an earlier case; that of Rachel Carson, well known for her book “Silent Spring” of 1962 in which she criticized the overuse of DDT and other pesticides. Carson's book was also strongly criticized and demonized. Kimm Groshong reviewed the story and she tells us in her 2002 study that:
The minutes from a meeting of the Manufacturing Chemists’ Association, Inc. on May 8, 1962, demonstrate this curious stance. Discussing the matter of what was printed in Carson’s serialization in the New Yorker, the official notes read: "The Association has the matter under serious consideration, and a meeting of the Public Relations Committee has been scheduled on August 10 to discuss measures which should be taken to bring the matter back to proper perspective in the eyes of the public."
Whether we can call that a "conspiracy" is open to discussion, but clearly there was an organized effort on the part of the chemical industry against Rachel Carson's ideas. By analogy, we could think that, in some smoke-filled room, representatives of the world's industry had gathered in the early 1970s to decide what measures to take against the Limits to Growth in order to “bring the matter back to proper perspective in the eyes of the public.” The recent story of the campaign against climate science, as told for instance by Hoggan and Littlemore (2010) and by Oreskes and Conway (2010), tells us that this kind of things have occurred and still occur.

We have no data indicating that something like that took place against "The Limits to Growth" and we'll probably never know. It is clear, anyway, that propaganda techniques are effective because they play on natural tendencies of the human mind. The 1989 article by Ronald Bailey and other attacks were no more than catalysts that unleashed our tendency to believe what we want to believe and to disbelieve what we don’t want to believe. We don't like inconvenient truths.

Now, in the early years of the 21st century, the general attitude towards the concepts of the "Limits" book seems to be changing again. The war, after all, is won by those who win the last battle. One of the first cases of reappraisal of the Limits study has been that of Matthew Simmons (2000), an expert on crude oil resources. It seems that the "peak oil movement" has been instrumental in bringing back to attention the Limits study and, indeed, oil depletion can be seen as a subset of the world model used in the study (Bardi 2008). Climate studies have also brought back the limits of resources to attention; in this case, intended as the limited capability of the atmosphere to absorb the products of human activities.

But it is not at all obvious that a certain view of the world, one that takes into account the finite amount of resources, is going to become prevalent, or even just respectable. The success of the smear campaign of the 1980s shows the power of propaganda and of urban legends in shaping the public perception of the world, exploiting our innate tendency of rejecting bad news.

Because of our tendency of disbelieving bad news, we chose to ignore the warning of impending collapse that came from the Limits study. In so doing, we have lost more than 30 years. Today, we are ignoring the warnings that come from climate science and we may be making an even worse mistake. There are signs that we may be starting to heed the warnings, but we are still doing too little, too late. Cassandra's curse is still upon us.

To know more on this subject, you can see my book "The Limits to Growth Revisited



Bailey, Ronald 1989, “Dr. Doom” Forbes, Oct 16, p. 45

Bardi, U. 2008, "Peak oil and the Limits to Growth: two parallel stories", The Oil Drum.

Cole H.S.D., Freeman C., Jahoda M., Pavitt K.L.R., 1973, “Models of Doom” Universe Books, New York

Golub R., Townsend J., 1977, “Malthus, Multinationals and the Club of Rome” vol 7, p 201-222

Groshong, K. 2002, "The Noisy Response to Silent Spring: Placing Rachel Carson’s Work in Context!, Pomona College, Science, Technology, and Society Department Senior Thesis

Hoggan, James; Littlemore, Richard (2009). Climate Cover-Up: The Crusade to Deny Global Warming. Vancouver: Greystone Books. ISBN 978-1553654858.

Nebbia, G. 1997, Futuribili, New Series, Gorizia (Italy) 4(3) 149-82

Nordhaus W., 1973 “Word Dynamics: Measurements without Data“, The Economic Journal n. 332.

Nordhaus W. D., 1992, “Lethal Models” Brookings Papers on Economic Activity 2, 1 Passel, P., Roberts, M., Ross L., 1972, New York Times, April 2

Oreskes, Naomi and Conway, Erik, 2010, "Merchants of Doubt", Bloomsbury, US

Simmons, M., 2000, “Revisiting The Limits to Growth: Could The Club of Rome Have Been Correct, After All?”

Tuesday, September 6, 2011

Cassandra and the limits to growth

Sometimes I wonder how it was that Cassandra, the Trojan prophetess, had so much trouble in convincing her fellow Trojan citizen that it was not such a good idea to demolish the city walls to let in that big, wooden horse. Maybe she spoke in riddles and using obscure language, as fitting for a prophetess. But in our case, facing global warming and resource depletion, I believe that it is fundamental today to arrange our knowledge in ways that can be understood by citizens and decision makers. Otherwise, all the work we have done will be lost and we'll remain just Cassandras.

In 1992, William Nordhaus wrote an article (1) where he strongly criticized "The Limits to Growth" (LTG) study. Referring to the 1972 version of LTG, he said that,

" seems apparent that the dynamic behavior of the enormously complicated Limits I model was not fully understood (or even understandable) by anyone, either authors or critics."

Which we may take as correct at least in one respect; that is, if Nordhaus meant to include himself among these "critics". Indeed, with this sentence, Nordhaus may have been admitting that his 1973 paper (2), where he had even more strongly criticized world modelling, was completely wrong. Simply, in 1973 he hadn't understood how the model worked, and not even in 1992. (I discuss in detail these papers by Nordhaus in my book "LTG Revisited" (3).)

It is also true that the large majority of those who criticized the first LTG study after its publication, in 1972, did so without really understanding world modelling. But is it true that the "world3" model at the basis of the study was not "understandable," as Nordhaus maintains? Possibly, Nordhaus had based his evaluation on this graph:

This is a scan of the graphical representation of the world3 model taken from my personal copy of the 1972 edition of LTG. The boxes are labelled in Italian but, either in English or in Italian, the logic of the model is very difficult to grasp. It appears just as a random collection of boxes and arrows, not unlike the plan of the subway of a major city. What you have here, indeed, is an example of a "spaghetti model", a typical bane of system dynamics (SD) models (as discussed, for instance, by Jacques Lefevre). It is possible that it is this complex and apparently haphazard scheme that confused LTG critics and supporters alike. It may have been one the reasons of the flood of criticism that accused the LTG study of being based on arbitrary assumptions, if not a hoax purposefully designed to trick the public. People just could't believe that the mass of spaghetti shown in the figure could generate to a cycle of growth and decline and that this cycle was to be the destiny of our economy.

But the world3 model was not arbitrary. As one of the first models of this kind in history, it is not surprising that its graphic representation left something to be desired. That didn't affect the performance of the model, which withstood very well the test of time. The real world parameters, so far, have behaved close to the results of the "base case" scenario of the 1972 LTG study, as Turner shows. Critics had to work hard to find weak points in the study that went beyond simple statements of disbelief, as I discussed in a post of mine. In the end, they had to settle on very minor points that had no relevance to the significance of the study.

The LTG model was not impossible to understand, either. If you look at the text of the original 1972 LTG book, you'll see that the figure shown above came only after several pages that described in detail how the model worked. The authors made a thorough job in showing diagrams of the various subsets of the model. That made the model understandable even by economists.

Unfortunately, that was not enough. No matter how well the model was explained, understanding LTG required an effort that most people were not willing to expend. It is difficult to fight against the human tendency of disbelieving bad news - the Cassandra effect, in short.

But we can learn something from the LTG experience. A fundamental point is related to the public perception of models. For a scientist, the need for models is obvious; but it is not so for a politician or for the public. In this sense, world modelling and modern Climate Science have the same problem. Both fields are seen as based on complex models that are beyond the capability of understanding of the non-specialist. So, what is exactly the role of models in the public debate on the issues of climate change and resource depletion?

Sometimes, people seem to believe in models just because they are complex. Otherwise they see complexity as proof that the model is wrong or irrelevant. The problem of complex models is that they leave people free to chose one or the other attitude, depending on their feelings or their political ideas. So, I think we badly need to frame our models in "mind sized bites" of knowledge - as suggested by Seymour Papert - that people can grasp.

As an example, here is how Magne Myrveit has represented the five main stocks of "The Limits to Growth" model (from a paper titled "The World Model Controversy").

This figure can be criticized as an oversimplification, but it is a huge step forward in the sense that it gives an immediate visual idea of what the main elements of the models are. Yet, it has a problem. "Mind sized" doesn't just mean reducing the number of elements in the model. It means, in my opinion, providing also a clue on what makes the model tick. In other words, a representation such as this one, simple as it is, still suffers from the spaghetti syndrome. It is static; it doesn't tell you anything on where the system is going. And, yet, the results of the calculations clearly show that the system is going somewhere; it is undergoing a cycle of growth and decline. That is not clear at all from this figure.

So, I think that if we want to make useful mind sized models we must clarify that there is a tendency; a force, the result of something that in technical terms is called a "potential". Potentials generate forces, and forces move things along. I think this is the point that Jacques Lefevre was doing when he used the metaphor of chemical reactions for describing system dynamics models. But there is an even simpler metaphor: "bathub dynamics"  as discussed by John Sterman and Linda Sweeney.

Now, this is a real mind sized model, in the sense that it is clear that it is gravity (better said, the gravitational potential) that moves water in a certain direction. This representation of the model is not static, it shows what happens. It was with this example in my mind that I proposed the "three tiered fountain" image as a representation of a simple world model:

Neither a bathub nor a fountain have the characteristic that we call "feedback", which is crucial in world models as it generates non linear growth and decline. Nevertheless, these are images that clarify the fact that the system is driven by a potential. Water must go somewhere and that is because of the gravitational potential. Then, it is clear that if we start from a limited reservoir of water, then at some moment it must run out. In a world model, it is not gravity that moves things, but thermodynamic potentials, in turn related to the energy stocked in the natural resources that an economy exploits. And it should be also clear that if natural resources exist in limited amounts, they must run out at some moment. So, we can build a simple, mind sized model as:

Once these points are understood, we can use even this very simple "three stock" models to gain a surprising wealth of insight on how economic systems behave. I used this model in previous posts and I showed how it can explain the "Seneca Effect", that is why the decline of economic and social systems is so often much faster than growth.

So, I think this is a line to pursue if we want our models to be understood and, more than all, acted upon. That is true for both resource depletion and climate change, which are two sides of the same coin. But would mind sized models solve the problem of the disconnection of scientists and decision makers? Well, that won't be easy, of course. Sometimes, when playing with these models, I see myself as if I really were the ancient Cassandra, the Trojan prophetess, drawing stock and flow diagrams on the sand in front of perplexed Trojan citizens. Not easy. Yet, I think we have to try.


1. Lethal Models 2: The Limits to Growth Revisited, by William Nordhaus Brookings Papers on Economic Activity, Vol 1992, No. 2 (1992), pp 1-59. URL: 

2. World Dynamics: Measurement Without Data,William D. Nordhaus, The Economic Journal, vol. 83, No. 332 (Dec., 1973), pp. 1156-118,

3. "The Limits to Growth Revisited" Ugo Bardi, Springer 2011


Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)