Something that people also often forget about the old Club of Rome predictions is that some of them were right. That is, they didn’t foresee massive recycling, but the reason we recycle 90 percent of the metal in a car isn’t out of concern for the environment.

Another thing: sometimes you can’t replace something with something else, not without a lot of other inputs. For example: most civilizations gave up the use of stone tools. But the inputs to make a metal tool are much greater; instead of just picking up a hunk of flint and chipping out a blade, you have to go and dig up the metal, smelt it, and forge it, and mix it (in the case of iron) with carbon to make steel. That’s a lot of other steps and a lot more energy input.

In a more modern context, there are some materials that we can’t replace, There isn’t any chemical replacement for oil — at least not one that has the energy density as a burned fuel. That’s just the laws of physics and chemistry. You can do without petroleum in many cases, but it’s going to require a change of lifestyle. In fact you could consume jut as much energy — you’d just be doing it differently. But differently nonetheless.

And there are plenty of instances where technological advances didn’t magically come up with a replacement for the stuff that people were running out of. Easter Islanders had no replacement for wood for boats, so fishing was going to be limited. And they weren’t stupid — they knew how to make a kind of concrete, not much different from the Romans. But no boats = no travel = no trade, even if they’d known where to go.

What I think is interesting about a lot of people who see this sort of endless cornucopia of technology is that they ignore the inputs problem completely.

On another note: think of how much oil we burned to protect the supply of “easy” oil in the Middle East. I wold bet money that the ROI is negative. It gets worse when you count up the man-hours and productivity that went into building the aircraft carriers we have parked out there.

I think you just did. 😉
BTW: A well known skeptic an author did write an excellent article about this very subject, google “The relativity of wrong” by Asimov.

“They made a number of “if things stay this way” predictions”

All predictions are ultimately based on assumptions, most people accept it as fact that “the sun will rise in the east tomorrow” but there are implicit assumptions in that statement, such as, gravity will continue to work as it has in the past, or the observer is not located at the pole.
How does one predict a “green revolution” a decade before it happens? It would be unreasonable to do so at a time when China was suffering African style famines that were broadcast on the nightly news. Who on Earth in the 60’s could see China would be a economic superpower currently consuming over a third of the world’s steel output in domestic infrastructure projects?

“bad assumptions”
Easy said with 20/20 hindsight but in practical terms how does one predict a “green revolution”? The fact their assumptions were broken voids the conclusions of a particular prediction but it does not void an entire branch of science.
Even Issac Newton made a “bad assumption” in his legendary Principa Mathematica. Of the two assumption it contained, one was “Time is constant”, 200+yrs later that assumption turned out to be “bad”.
The thing is, the discovery that time was relative did not invalidate Newton’s work, it merely limited its previously universal applicability.
Few people realize that Newton wrote more about theology than he did about science, much of that writing would be considered the ranting of a madman today, for example he claimed “Jesus was sent to Earth to operate the levers of gravity”. Yet all that is forgotten and he is universally recognized as one of the most prolific polymaths of all time.

Ehrlich is certainly not in the same league as Newton, however his critics often expect him to make less “bad assumptions”. Personally I think the root of the problem is that many of his critics are looking for absolute certainty and then start complaining when science stubbornly refuses to provide it. Broken assumptions are a normal part of science that go right back to the start of the modern scientific era when science split from the church. If people want absolute certainty they should join a religion and stay away from apple trees.

I mention this because of one of their predictions. Their assumption was that access to more metallic ores were one of the most factors in the ability of our civilization to continue. One of their predictive scenarios was that we would obtain virtually unlimited cheap metal ore from the ocean floor (remember magnesium nodules?). Their prediction was that this would make the future even worse. Short term prosperity would lead to a population boom which would over-stress other factors in their algorithm, leading to an even earlier collapse of civilization.

Here, I think they had something very right, though they didn’t know it. They pretty much were unaware of the possibilities of replacement materials. In materials, some of those replacements have been good, some have been bad in the long term. In the short term, they screwed up their model. We know that lesson now. The whole battle we are fighting now is about doing things the same way into the future (oil), which we know is impossible; accelerating the “same way”, which might make things better in the short run (“things” meaning quality of life), but which will definitely make things worse in the long run (tar sands and coal); and finding replacements (wind, tidal, solar, and, who knows what until we try…).

Damn. This might be a publishable article if I knew how to publish an article.