sábado, julho 05, 2008

O Clube de Roma e "Os Limites do Crescimento"


O relatório (ver aqui e aqui) publicado em 1972 para o Clube de Roma ( ver página da organização aqui ) por uma equipa do MIT, tem ganho nova actualidade com a crise energética, a urgência do combate às alterações climáticas, a crise alimentar e à dinâmica que relaciona todas estas variáveis.
Desde que foi publicado, "Os Limites do Crescimento" suscitaram enorme polémica, desde logo porque vieram pôr em causa a ideologia do crescimento económico, a ideia de que era possível continuar a produzir e a consumir recursos, com elevado desperdício, diga-se, como se não existissem limites para a capacidade de regeneração e assimilação pela Natureza dos resíduos produzidos, para a população que o planeta poderia suportar e para os próprios "stocks" ou dotações de minerais, combustíveis, água potável, solo arável, etc.

Os críticos, nas décadas seguintes, apontaram o falhanço das previsões de "Os Limites do Crescimento" referindo-se aos dados apresentados no relatório (ver aqui). Como exemplo, o petróleo não duraria mais de 31 anos, ou seja, ter-se-ia esgotado em 2003 (!). No entanto, o relatório não pretendeu fazer previsões, nem foi isso que fez. Quem tiver acesso ao mesmo (versão portuguesa Publicações D. Quixote) pode verificar que tratava-se de cenários e não de previsões. O cenário de 31 anos baseava-se no conhecimento das reservas publicadas pelo Departamento de Minas dos EUA em 1970 e à taxa de consumo da época. Mas havia outro cenário que apontava para 50 anos, caso as reservas fossem 5 vezes maiores e a taxa de crescimento médio anual fosse de 3.9%! Mas os críticos podem continuar a dizer: tal como estavam erradas as estimativas de reservas de então, podem também estar erradas as de hoje. É possível. Mas devemos ter em conta dois factos: a enorme evolução tecnológica (nomeadamente com os satélites, que em 1970 ainda estavam a dar os primeiros passos) dos últimos trinta anos e sobretudo a história da prospecção. O pico das descobertas ocorreu nos anos 60/70.
O que os investigadores de "Os Limites do Crescimento" pretenderam fazer foi sobretudo chamar a atenção para a natureza do crescimento exponencial e de como isso colidia com a finitude dos recursos. O objectivo deles era precisamente evitar que esta colisão existisse e, em última análise, adiar o mais possível os limites indicados nos seus próprios cenários ( de outro modo não teria valido a pena o esforço - é isto que os críticos não entendem!) . E de facto, sobretudo com os choques petrolíferos, a eficiência aumentou bastante. Mas isso não foi suficiente, e afinal o cenário de 50 anos talvez não esteja tão longe da verdade. Ler também "Revisiting The Limits to Growth: Could The Club of Rome Have Been Correct, After All?"

5 comentários:

Wyrm disse...

E foram precisos uns sábios para se aperceberm disso?

Hydrofluoric disse...

By definition, energy "sources" must produce more energy than they consume, otherwise they are called "sinks". By definition, energy sources will "run out" when they consume more energy than they produce.

This universal energy law holds no matter how high the money price of energy goes. Economists completely overlook this basic energy law and have misled government regulators all over the world. Economics cannot violate the 2nd law of thermodynamics.

Here is part of an interview with Nobel Prize-winning economist Milton Friedma, worth quoting at length because of his colossal stupidity:

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Ravaioli: But there are many other environmental problems ...

Nobel Laureate Friedman: Of course. Take oil, for example. Everyone says it's a limited resource: physically it may be, but economically we don't know. Economically there is more oil today than there was a hundred years ago. When it was still under the ground and no one knew it was there, it wasn't economically available. When resources are really limited prices go up, but the price of oil has gone down and down. Suppose oil became scarce: the price would go up, and people would start using other energy sources. In a proper price system the market can take care of the problem.

Ravaioli: But we know that it takes millions of years to create an oil well, and we can't reproduce it. Relying on oil means living on our capital and not on the interest, which would be the sensible course. Don't you agree?

Nobel Laureate Friedman: If we were living on the capital, the market price would go up. The price of truly limited resources will rise over time. The price of oil has not been rising, so we're not living on the capital. When that is no longer true, the price system will give a signal and the price of oil will go up. As always happens with a truly limited resource.

Ravaioli: Of course the discovery of new oil wells has given the illusion of unlimited oil …

Nobel Laureate Friedman: Why an illusion?

Ravaioli: Because we know it’s a limited resource.

Nobel Laureate Friedman: Excuse me, it's not limited from an economic point of view. You have to separate the economic from the physical point of view. Many of the mistakes people make come from this. Like the stupid projections of the Club of Rome: they used a purely physical approach, without taking prices into account. There are many different sources of energy, some of which are too expensive to be exploited now. But if oil becomes scarce they will be exploited. But the market, which is fortunately capable of registering and using widely scattered knowledge and information from people all over the world, will take account of those changes. [1]

[1] Milton Friedman quoted in p. 33, ECONOMISTS AND THE ENVIRONMENT, Carla Ravaioli; Zed, 1995;
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In fact, none of the Club of Rome's predictions has failed. Economists like Friedman routinely misrepresent the study in order to further their global political/ideological agendas.

José M. Sousa disse...

Yes, you are right about most of economists. Friedman certainly was not a stupid person, so one only can guess he was really promoting an ideological agenda.
The problem with many economics teaching is that it focus to much on financial matters, which tend to ignore the physical world. That's why we are in crisis.

Hydrofluoric disse...

Jose' Sousa,

No doubt Friedman was not a stupid person regarding the type of society he helped to create but what he said in the interview quoted above makes no sense at all and it is a clue to the very shaky foundations of that society.

Nevertheless he was right when he said "there is not such thing as a free lunch" and a good example of that is the rampant use over the last 100 years or so of a low entropy, high quality source of energy, petroleum. Unfortunately the people that are going to pay for all this orgy of cheap energy consumption will very unlikely be the ones that enjoyed it.

Of course, this conceited view of human progress (whatever that is) is not restricted to laissez-faire right wingers. Both Marxists and free-market economists never tire to ridicule that other living things have intrinsic value. In their view all of the earth ecosystems are there just for the satisfaction of human ambitions.

The view of things in which we are separate from the rest of nature and can live with minimal concern for the biosphere is not a conclusion of rational inquiry, it is an inheritance from a humanly aberrant religious tradition.

José M. Sousa disse...

Yes, I absolutely agree. We are living a colective madness in our disregard towards nature. And I also agree that both right and left, in spite of some rhetoric of the late, share this ideology of constant economic growth which is in collision with the biosphere.