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Be it known… This entry was written as a complement to one that was posted earlier last week, entitled “Beyond Environment: Falling Back In Love With Mother Earth.”

Someone once said, “The trouble with weather forecasting is that it’s right too often for us to ignore it and wrong too often for us to rely on it.” But ever since I read this, I’ve been looking at my local weather forecasts everyday now for nearly two years straight… And I’ve got to say, looking one day ahead, the MET Office seem to get it near on 95% right every time… Seriously, you don’t have to take my word on this. Just check it out for yourselves. Saying, I noticed that when the MET Office begin to make general forecasts that are five days in to the future, their accuracy falls quite substantially. On the whole – while I haven’t been taking as much notice of these 5 day forecasts – I’d say they tend to get them near on 60% right. Now that, in my books, is definitely good predicting. How do they do it? Well, they’ve been using some of the world’s biggest and best super computers to crunch all the raw numerical data that is gathered from a vast array of sources (both manual and remote sensing data posts), of which they literately have thousands: on military air fields, to all the way out at sea. The gathering of this diverse spread of data gives them a really unique (and very accurate) perspective on weather patterns here in the UK, demonstrating how temperature, wind, sun, rain, cloud and other meteorological phenomena all feedback into each other to create the daily weather patterns that we observe in our daily lives.

But is it really a clear cut and easy to understand science when trying to understand how these individual phenomena affect each other? As some of you may already know, Edward Lorenz pretty much made a big discovery back in 1961 when looking at weather systems while studying computer simulations. He basically noticed the unexpected unfolding of a weather simulation as the result of a shortcut that he took by entering data to only three decimal places rather than six. As a result, this sensitivity to initial conditions was something that has been well studied over the last 50 years, being called Chaos Theory. The MET know a lot about how non-linear dynamics operate within weather systems here on Earth… In fact they’re presently doing a lot research into the sensitivity of the Earth’s weather system and how human activities affect it. If you ask me whether mankind is seriously affecting the environment in which he lives through his activities… I’d tell you a very big, “YES!” Just as Lorenz saw huge unexpected variances in his computer simulations, one’s that occurred from simply varying miniscule amounts in the data that was being entered at the beginning, so too will mankind see even bigger changes in the weather systems that we expect to see here on Earth. It’s not joke… Mankind isn’t varying the environment by minuscule amounts anymore, as we might have done 2000 years ago… We’re slashing the environment to pieces by whacking great asphalt cities down all over the Earth, by burning 400 years worth of energy stored by plants from the sun, by building dams to regulate the earth’s natural water flow, by turning ancient forests into agricultural land, etc…

On the whole I try to be as optimistic as possible through my general outlook on everything we as human being do. Saying that, I was never the type of person who would adorn an overly positive outlook about something just because being positive would make the situation better. To me, that’s a bit like thinking that you can fly and then throwing yourself off the top of a building, expecting to be able navigate the air currents safely back down to earth. Not my style. If you want to be that positive, then try taking off from the ground first. At least then you’ll know whether or not your positivity and belief in your ability is justified. So, that’s it. I suppose I’d rather get my facts straight and look at whatever situation I was in from as open minded a view as possible, regardless of what it was going to elucidate. I mean, I can play a bit of guitar and some very basic piano, but can’t read music off a staved sheet very well at all. So perhaps I wouldn’t remain positive about the fact that I could proficiently play Debussy’s Arabesque #1 after only one week of solitary practice with nothing more than a musical score to guide me… But I could perhaps muster a half decent attempt after one week of tuition with a good teacher and with access to a audible version of the music too.

And that’s my point here… There are different variables within certain parameters of any given situation that, when viewed by an observer, define whether or not one could feel positive about obtaining a particular outcome for that given situation. If some of the most obvious parameters for success are not present, masked over by a general optimistic view that things will work out, so whey bother trying too hard… After which one still feels exceedingly positive about obtaining a result… Well, my common sense would either tell me to lower my positive outlook about the outcome of events, or pull my finger out and get on with working out a way to succeed.

Nina Fedoroff was recently quoted saying, “We are sliding back into a dark era, and there seems little we can do about it.” During a conference last week, the president of the American Association for the Advancement of Science (AAAS) confessed that she was “scared to death” by the anti-science movement that was spreading, uncontrolled, across the US and the rest of the western world. While I feel that this statement might be a little too strong for my own stance on this general “head in the sand” tactic, I do empathise with Fedoroff because her natural survival instinct – the one that watches a friend get eaten by a tiger, so that when she’s sees another tiger she runs, rather than stroking the rather large and cuddly cat – is obviously telling her that a lot of folk out there do not share her concern for where we, as a civilization on a planet, are heading. Many have no real desire to understand too much about what sustainability actually is, let alone steer their lives into modes of minimizing capitalist consumption by growing their own food, managing their own woodlands for fire wood, insulating their homes, giving up their cars, etc…

For me, this is a bit like the case of thinking one can fly and going straight to the top floor of the Empire State building and launching themselves off the top parapet. Yes, they might think that they’re flying as they SWOOSH past floor after floor, hurtling towards the solid asphalt below at breakneck speed. But is it really flying? I mean, can they sustain the period of time that they’re in the air for without the sudden SPLAT at the end? I mean… Can we sustain even half the number of human beings at our present rates of consumption? Can we sustain this huge spurt of uncontrolled growth that mankind is witnessing in the 21st century? In fact… Just how many people do you think the earth can support?

You see… When one of the world’s most distinguished agricultural scientists tells me that she’s “scared to death” by what she sees going on around her… Doing so at one of the most well known annual scientific meetings. Well… My commonsense tells me to at least oblige this lady and have a listen to what she has to say. “We are sliding back into a dark era,” Fedoroff said. “And there seems little we can do about it. I am profoundly depressed at just how difficult it has become merely to get a realistic conversation started on issues such as climate change or genetically modified organisms.”

Would you believe… Just like the MET Office studies weather patterns in order to forecast the coming day’s weather, so to are there people looking at today’s and yesterday’s global patterns of human growth and resource consumption, who are making predictions about what the future might hold for us. And I’ve got to say, while these studies might not be as detailed or as developed as some of the weather studies that the MET Office are conducting… The ones that have come to light certainly show us something that we should be heeding.

Like I said… I’m quite an optimistic person. But I still read and/or listen to the weather forecasts every morning… And if there’s a chance that it’ll be a rainy, cold, wet and windy day, I won’t remain optimistic that the weather might suddenly change to something better and wear nothing by my shorts and a T-shirt. I mean, I already know from observation how accurate the MET Office’s weather forecasting can be… For them to be able to make these predictions, the observations come from which their science was built from, along with their forecasts, must be quite accurate and sound. I mean 95% accuracy for one day ahead is near on great. Thus I base my actions for the coming day on this forecast, like whether I should take umbrella with me, or wear shorts and sunglasses, etc… The way the professionals do their stuff down at the MET Office instils in me an air of confidence about what they do and how they do it… So I listen to them when the advise us on the weather.

Likewise, having studied a scientific discipline myself at university, one that looked at methods for detecting illnesses within the human body, I know that there is great accuracy in these methods. They are used time and again to catch people with cancer, bacterial infections, etc… And they do so with near on 85% accuracy. So, on the whole, I have great respect for the discipline of scientific study… And I have a great respect for many of those involved in the areas of science. Don’t get me wrong… We’re not perfect. Just like the MET Office only get 95% of the coming days’ forecasts right, other areas of science don’t get it right all the time either. But should those scientist be branded with that lousy 5% margin of error? In my humble opinion, I’d rather reap the benefits of that 95% accuracy than let the 5% error bother me. So when some other professionals/scientists say something that I see to be important for all our future well fair here on Earth, I usually give it at least a once over before I decide whether to ignore it or not… At least a once over!

So I’ll finish here by saying… If most of you want us all to jump off the building because you think you can fly, there is no way on Earth (or in the air) that I’m gonna keep quiet and pretend that I can sustain this ‘flight’ while I’m hurtling past the windows of the building that we’ve all just jumped off from, just to keep the majority of you lot happy. Like I said… It’s not my style. My survival instinct is telling me that I want to survive, regardless of whether you do or not. And if I’m falling down – rather than flying down – with the rest of you, I’m gonna engage in some chit-chat on the way down about how to survive this fall.

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Doomsday Book

Forty years ago, a highly controversial study warned that we had to curb growth or risk global meltdown. Was it right?

AT THE beginning of the 1970s, a group of young scientists set out to explore our future. Their findings shook a generation and may be even more relevant than ever today.

The question the group set out to answer was: what would happen if the world’s population and industry continued to grow rapidly? Could growth continue indefinitely or would we start to hit limits at some point? In those days, few believed that there were any limits to growth – some economists still don’t. Even those who accepted that on a finite planet there must be some limits usually assumed that growth would merely level off as we approached them.


In most runs of the World3 computer model, rapid growth is followed by sharp decline. So far the standard run (main graphic) corresponds well with measurements of real world equivalents (dotted lines).


These notions, however, were based on little more than speculation and ideology. The young scientists tried to take a more rigorous approach: using a computer model to explore possible futures. What was shocking was that their simulations, far from showing growth continuing forever, or even levelling out, suggested that it was most likely that boom would be followed by bust: a sharp decline in industrial output, food production and population. In other words, the collapse of global civilisation.

These explosive conclusions were published in 1972 in a slim paperback called The Limits to Growth. It became a bestseller – and provoked a furious backlash that has obscured what it actually said. For instance, it is widely believed that Limits predicted collapse by 2000, yet in fact it made no such claim. So what did it say? And 40 years on, how do its projections compare with reality so far?

The first thing you might ask is, why look back at a model devised in the days when computers were bigger than your fridge but less powerful than your phone? Surely we now have far more advanced models? In fact, in many ways we have yet to improve on World3, the relatively simple model on which Limits was based. “When you think of the change in both scientific and computational capabilities since 1972, it is astounding there has been so little effort to improve upon their work,” says Yaneer Bar-Yam, head of the New England Complex Systems Institute in Cambridge, Massachusetts.

It hasn’t happened in part because of the storm of controversy the book provoked. “Researchers lost their appetite for global modelling,” says Robert Hoffman of company WhatIf Technologies in Ottawa, Canada, which models resources for companies and governments. “Now, with peak oil, climate change and the failure of conventional economics, there is a renewed interest.”

The other problem is that as models get bigger, it becomes harder to see why they produce certain outcomes and whether they are too sensitive to particular inputs, especially with complex systems. Thomas Homer-Dixon of the University of Waterloo in Ontario, Canada, who studies global systems and has used World3, thinks it may have been the best possible compromise between over-simplification and unmanageable complexity. But Hoffman and Bar-Yam’s groups are now trying to do better.

World3 was developed at the Massachusetts Institute of Technology. The team took what was known about the global population, industry and resources from 1900 to 1972 and used it to develop a set of equations describing how these parameters affected each other. Based on various adjustable assumptions, such as the amount of non-renewable resources, the model projected what would happen over the next century.

The team compares their work to exploring what happens to a ball thrown upwards. World3 was meant to reveal the general behaviour that results – in the case of a ball, going up and then falling down – not to make precise predictions, such as exactly how high the ball would go, or where and when it would fall. “None of these computer outputs is a prediction,” the book warned repeatedly.

Assuming that business continued as usual, World3 projected that population and industry would grow exponentially at first. Eventually, however, growth would begin to slow and would soon stop altogether as resources grew scarce, pollution soared and food became limited. “The Limits to Growth said that the human ecological footprint cannot continue to grow indefinitely, because planet Earth is physically limited,” says Jørgen Randers of the Norwegian School of Management in Oslo, one of the book’s original authors.

What’s more, instead of stabilising at the peak levels, or oscillating around them, in almost all model runs population and industry go into a sharp decline once they peak. “If present growth trends in world population, industrialisation, pollution, food production and resource depletion continue unchanged, the limits to growth on this planet will be reached sometime within the next 100 years. The most probable result will be a sudden and rather uncontrollable decline in both population and industrial capacity,” the book warned.

This was unexpected and shocking. Why should the world’s economy collapse rather than stabilise? In World3, it happened because of the complex feedbacks between different global subsystems such as industry, health and agriculture. More industrial output meant more money to spend on agriculture and healthcare, but also more pollution, which could damage health and food production.

And most importantly, says Randers, in the real world there are delays before limits are understood, institutions act or remedies take effect. These delayed responses were programmed into World3. The model crashed because its hypothetical people did not respond to the mounting problems before underlying support systems, such as farmland and ecosystems, had been damaged.

Instead, they carried on consuming and polluting past the point the model world could sustain. The result was what economists call a bubble and Limits called overshoot. The impact of these response delays was “the fundamental scientific message” of the study, says Randers. Critics, and even fans of the study, he says, didn’t get this point.

The other message missed was that Limits was about how catastrophe could be averted. It did not say that humanity was doomed. In model runs where growth of population and industry were constrained, growth did level out rather than collapse – the stabilised scenario (see graph).

Yet few saw it this way. Instead, the book came under fire from all sides. Scientists didn’t like Limits because the authors, anxious to publicise their findings, put it out before it was peer reviewed. The political right rejected its warning about the dangers of growth. The left rejected it for betraying the aspirations of workers. The Catholic church rejected its plea for birth control.

Critical Points

The most strident criticisms came from economists, who claimed Limits underestimated the power of the technological fixes humans would surely invent. As resources ran low, for instance, we would discover more or develop alternatives.

Yet the Limits team had tested this. In some runs, they gave World3 unlimited, non-polluting nuclear energy – which allowed extensive substitution and recycling of limited materials – and a doubling in the reserves of nonrenewables that could be economically exploited. All the same, the population crashed when industrial pollution soared. Then fourfold pollution reductions were added as well: this time, the crash came when there was no more farmland.

Adding in higher farm yields and better birth control helped in this case. But then soil erosion and pollution struck, driven by the continuing rise of industry. Whatever the researchers did to eke out resources or stave off pollution, exponential growth was simply prolonged, until it eventually swamped the remedies. Only when the growth of population and industry were constrained, and all the technological fixes applied, did it stabilise in relative prosperity.

The crucial point is that overshoot and collapse usually happened sooner or later in World3 even if very optimistic assumptions were made about, say, oil reserves. “The general behaviour of overshoot and collapse persists, even when large changes to numerous parameters are made,” says Graham Turner of the CSIRO Ecosystem Sciences lab in Crace, Australia.

This did not convince those who thought technology could fix every problem. And with so much criticism, the idea took hold that Limits had been disproved. That mantra has been repeated so often that it became the received wisdom, says Ugo Bardi of the University of Florence in Italy, author of a recent book about Limits. “The common perception is that the work was discredited scientifically. I heard it again at a meeting last April,” says Homer-Dixon. “It wasn’t.”

It wasn’t just confusion. “Misunderstanding was enhanced by a media campaign very similar to the one that has been recently directed against climate science,” says Bardi.

One of the most common myths is that Limits predicted collapse by 2000. Yet as a brief glance at the “standard run” shows, it didn’t (see graph). The book does mention a 1970 estimate by the US Bureau of Mines that the world had 31 years of oil left. The bureau calculated this by dividing known reserves by the current rate of consumption. Rates of consumption, however, were increasing exponentially, so Limits pointed out that in fact oil had only 20 years left if nothing changed. But this calculation was made to illustrate the effects of exponential growth, not to predict that there were only 20 years of oil left.

When Matthew Simmons, a leading oil-industry banker, finally read Limits in the 1990s, he was surprised to find none of the false predictions he had heard about. On the contrary, he concluded, population and energy growth largely matched the basic simulation. He felt Limits got so much attention, then lost it, partly because the oil shock of 1973 focused minds on resource shortages that were then largely resolved.

There have been other recent re-appraisals of the book. In 2008, for instance, Turner did a detailed statistical analysis of how real growth compares to the scenarios in Limits. He concluded that reality so far closely matches the standard run of World3.

Does that mean we face industrial collapse and widespread death? Not necessarily. A glance at Turner’s curves shows we haven’t yet reached the stage of the standard run, later this century, when such events are predicted.

In the model, overshoot and collapse are preceded by exponential growth. Exponential growth starts out looking just like linear growth, says Bar-Yam: only later does the exponential curve start heading skywards. After only 40 years, we can’t yet say whether growth is linear or exponential.

We already know the future will be different from the standard run in one respect, says Bar-Yam. Although the actual world population up to 2000 has been similar, in the scenario the rate of population growth increases with time – one of the exponential drivers of collapse. Although Limits took account of the fact that birth rates fall as prosperity rises, in reality they have fallen much faster than was expected when the book was written. “It is reasonable to be concerned about resource limitations in fifty years,” Bar-Yam says, “but the population is not even close to growing [the way Limits projected in 1972].”

The book itself may be partly responsible. Bar-Yam thinks some of the efforts in the 1970s to cut population growth were at least partly due to Limits. “If it helped do that, it bought us more time, and it’s a very important work in the history of humanity,” he says.

Yet World3 still suggests we’ll hit the buffers eventually. The original Limits team put out an updated study using World3 in 2005, which included faster-falling birth rates. Except in the stabilising scenario, World3 still collapsed.

Otherwise, the team didn’t analyse the correspondence between the real world and their 1972 scenarios in detail – noting only that they generally match. “Does this correspondence with history prove our model was true? No, of course not,” they wrote. “But it does indicate that [our] assumptions and conclusions still warrant consideration today.”

This remains the case. Forty years on from its publication, it is still not clear whether Limits was right, but it hasn’t been proved wrong either. And while the model was too pessimistic about birth and death rates, it was too optimistic about the future impact of pollution. We now know that overshoot – the delayed response to problems that makes the effects so much worse – will eventually be especially catastrophic for climate change, because the full effects of greenhouse gases will not be apparent for centuries.

There will be no more sequels based on World3, though. The model can no longer serve its purpose, which was to show us how to avoid collapse. Starting from the current conditions, no plausible assumptions produce any result but overshoot. “There is no sense in only describing a series of collapse scenarios,” says Dennis Meadows, another of the original authors of Limits.

Randers, meanwhile, is editing a book called The Next Forty Years, about what we can do when limits start to bite. “I don’t like the resulting future, but it should be described, particularly because it would have been so easy to make a much better future,” he says.

The only hope is that we can invent our way out of trouble. Our ingenuity has allowed us to overcome many limits, says Homer-Dixon, and we can’t predict what revolutionary technological innovations humanity might come up with. Yet he is pessimistic: “The question is, can we deliver ingenuity at an increasing rate indefinitely.” Because that is what we’ll need to do if growth continues.

Instead of declaring we are doomed, or proclaiming that technology will save us, we should explore the future more rigorously, says Bar-Yam. We need better models. “If you think the scientific basis of those conclusions can be challenged, then the answer is more science,” he says. “We need a much better understanding of global dynamics.”

We need to apply that knowledge, too. The most important message of Limits was that the longer we ignore the problems caused by growth, the harder they are to overcome. As we pump out more CO2, it is clear this is a lesson we have yet to learn.

by Debora MacKenzie (who is a consultant for New Scientist based in Brussels, Belgium)

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