“I’m right there in the room and no one acknowledges me.”
We must face the prospect of changing our basic way of living. This change will either be made on our own initiative in a planned way, or forced on us with chaos and suffering by the inexorable laws of nature.
Jimmy Carter (1976)
Before we discuss this Elephant in the Room we must first briefly consider the notion of ‘sustainability’. Too often people debate sustainability issues from an understanding that is vague, incomplete or frankly flawed.
"Just exactly what is meant when the word 'sustainable' or ‘sustainability’ are used?" They are popularly used to describe a wide variety of activities which are generally ecologically laudable but which may not be sustainable.
First, we must accept the idea that "sustainable" has to mean “for an unspecified long period of time.”
Secondly we have a spectrum for the use of the term "sustainable." At one end of the spectrum, the term is used with precision by people who are introducing new concepts as a consequence of thinking profoundly about the long-term future of the human race. In the middle of the spectrum, the term is simply added as a modifier to the names and titles of very beneficial studies in efficiency, etc. that have been in progress for years. In some cases the term may be used mindlessly (or possibly with the intent to deceive) in order to try to shed a favourable light on continuing activities that may or may not be capable of continuing for long periods of time.
The Government of the United Kingdom defines a ‘sustainable community’ in its 2003 Sustainable Communities Plan: ‘Sustainable communities are places where people want to live and work, now and in the future. They meet the diverse needs of existing and future residents, are sensitive to their environment, and contribute to a high quality of life. They are safe and inclusive, well planned, built and run, and offer equality of opportunity and good services for all.’
So there briefly we have “sustainable”?
If we follow on from the above we can see that a ‘sustainable population’ would be one that can survive over the long term, I am talking of thousands to tens of thousands of years, without running out of resources or damaging the environment in the process. This means that most of the resources we use have to be both renewable through natural processes and entirely recycled if they are not renewable. Our numbers and level of activity must not generate more waste than natural processes can return to the biosphere. A sustainable population must not grow past the point where those natural limits are breached.
If the population does exceed the carrying capacity, the death rate will increase until the population numbers are stable. Using these criteria it is obvious that the current human population is not sustainable.
In the entire environmental-related discussion taking place, population is a word we seldom dare to speak and it is conspicuous by its absence: Population is the elephant in the room.
It is obvious that something has massively increased the world's carrying capacity in the last 150 years. During the first 1800 years of the Common Era, like the tens of thousands of years before, the population rose very gradually as humanity spread across the globe. Around 1800 this began to change, and by 1900 the human population was rising dramatically:
That something is oil.
As we all know, but are sometimes reluctant to contemplate, oil is a finite, non-renewable resource. This automatically means that its use is not sustainable. Oil and Natural Gas are finite! There may be arguments over how much oil/gas there was/is but, regardless of what that number is they are finite, absolute.
If the use of oil is not sustainable, then of course the added carrying capacity the oil has provided is likewise unsustainable. Carrying capacity has been added to the world in direct proportion to the use of oil, and the disturbing implication is that if our oil supply declines, the carrying capacity of the world will automatically fall with it.
These two observations (that oil has expanded the world's carrying capacity and oil use is unsustainable) combine to yield a further implication. While humanity has apparently not yet reached the carrying capacity of a world with oil, we are already in drastic overshoot when you consider a world without oil. In fact our population today is at least five times what it was before oil came on the scene. If this sustaining resource were to be exhausted, our population would have no option but to decline to the level supportable by the worlds lowered carrying capacity.
What are the chances that we will experience a decline in our global oil supply? Of course given that oil is a finite, non-renewable resource, such an occurrence is inevitable. The field of study known as Peak Oil has generated a vast amount of analysis that indicates this decline will happen soon, and may even be upon us right now. The decline in oil supply will reduce the planet's carrying capacity, thus forcing humanity into overshoot with the inevitable consequence of a population decline.
The rapidity of the decline following the peak will determine whether our descent will be a leisurely stroll down to the canyon floor or a headlong tumble carrying a little sign reading, "Help!"
Each of the global problems we face today is the result of too many people using too much of our planet's finite, non-renewable resources and filling its waste repositories of land, water and air to overflowing. The true danger posed by our exploding population is not our absolute numbers but the inability of our environment to cope with so many of us doing what we do.
But are there other factors besides these that may contribute to overshoot with the inevitable consequence of a population decline.
The United Kingdom
UK population growth is environmentally unsustainable, and if it is environmentally unsustainable it is also economically unsustainable, for without ecologically healthy land our economy will not be able to support its own people without causing damage to the environment.
Today, the UK population is about 62 million and is one of the most crowded areas in the world. In 1750, when the Industrial Revolution was beginning, it was about 6 million. It had never exceeded this figure, although during the Dark Ages and after the Black Death it fell to one or two million.
Most people lived and died in poverty. Pre-industrial farmers were pushed to the limit to feed so many. The population increased slightly in years with good harvests, but starvation and malnutrition cut it back to the 6 million norm when harvests were bad.
We are in fantasy land if we think that we can continue to support the number of people that we do now without the full input of oil and its related products.
We have become so dependent on those fuels, that there is no way we can sustain ourselves at this population density and level of technology without them. Even something as basic as food will become impossible to produce, process and transport for our present numbers without fuel.
Just as redistributing greenhouse gas emissions is no solution to climate change, population redistribution provides no long-term solution to environmental sustainability - total population numbers need to decrease both in the UK and worldwide, alongside efforts to reduce people's individual environmental impacts.
By adding over two million more people (extra producers of greenhouse gas emissions through household, transport and business use) to the population of the UK since 1997, and by allowing the number of climate changers to rise by more than 300,000 people a year, the government's population policy has undermined most of its environmental goals.
The climate change scenario for the UK is one of initial warming. Longer drier summers and stormy wetter winters are predicted, based on a temperature rise of 2/3.5° Celsius for the UK by the 2080s [UK Climate Impacts Programme, 2002]. 
But a 5.8° Celsius rise is possible, with some climate scientists suggesting even faster warming. In the UK, 2006 was the warmest year since records began in 1659.
The Benfield Hazard Research Centre at University College, London, has produced maps of Britain showing the additional impact of sea-level rise under three scenarios. 
There is also increasing evidence of another worrying scenario - the possible failure of the Gulf Stream that keeps Britain's climate warm. Without it, the UK would be plunged rapidly into freezing temperatures that would prevail for many generations, and be unable to support its current population of nearly 60 million.
Extremes of temperature and climate, combined with weather-related disruptions, would severely reduce the size of the country's population carrying capacity.
The UK does not need to be wholly self-sufficient in food, but with population continuing to grow, urbanisation eating up farmland, and more of our remaining agricultural land likely to be used for energy crops, food production will be further squeezed.
The introduction of genetically modified organisms (GMOs) into the biosphere poses a danger similar to that of disease. When a plant GMO is created, its pollen spreads around the world. It is quite conceivable that much of mankind’s food supply could be eliminated, simply by a terrible error in which the introduction of one or more GMOs resulted in the global loss of harvests of a staple food, such as a cereal grain. 
The systems that produce the world's food supply are heavily dependent on fossil fuels. Vast amounts of oil and gas are used as raw materials and energy in the manufacture of fertilisers and pesticides, and at all stages of food production: from planting, irrigation, feeding and harvesting, through to processing, distribution and packaging.
In addition, fossil fuels are essential in the construction and the repair of equipment and infrastructure needed to facilitate this industry, including farm machinery, processing facilities, storage, ships, trucks and roads. The industrial food supply system is one of the biggest consumers of fossil fuels and one of the greatest producers of greenhouse gases.
Almost every current human endeavour from transportation, to manufacturing, to electricity to plastics, and especially food production is inextricably intertwined with oil and natural gas supplies. We are now at a point where the demand for food/oil continues to rise, while our ability to produce it in an affordable fashion is about to drop.
Changing consumption patterns reflecting higher material living standards are causes which can be mitigated by changing habits and better recycling, but the 2000-06 rate of increase in municipal waste exactly matches that of population growth. As each individual recycles more of his or her own waste, success is undermined by the constantly increasing numbers of people who create waste.
Among the alternative power proposals is wind power. Wind power is clean and carbon-free, and if the UK's offshore air currents remain as prevalent as they are today, it will remain the most promising proven source of renewable energy until and if technological innovations improve prospects for solar, wave and tidal power.
But how much land would be needed to provide all our electricity. It depends how much wind power can be constructed offshore. If half the 25,200 MW target for 2020 (estimated to provide a fifth of UK electricity) were built onshore, 3,100 square kilometres of land would be needed - an area larger than the whole county of Dorset (2,653 sq km). For wind power to supply all-electric homes at today's rates of consumption, for today's 60 million people, several counties would need to be covered with wind turbines.
Turbines are being built to rated capacities above 1MW, but whatever the capacity of a turbine, and whatever the improvement in energy yield per hectare, these calculations apply only to household electricity demand - if wind power were to be used to produce hydrogen fuel cells as a substitute for petrol for motor transport, land requirements for turbines would rise further.
The total amount of water used in UK (on a per person basis, but including domestic, industrial and agricultural withdrawals) is modest – about 550 litres per day - compared to the majority of countries in the world, because agriculture can be carried on mostly without irrigation.
The UK Government attaches importance to the goal of lowering water use per household because of increasing water constraints: rivers reduced to a trickle for several months, reservoir levels dropping, water tables (for groundwater supplies) continuing to drop. The large increases in the UK population experienced during the last five years makes it even more important to try to push per person consumption downwards.
Against this background, it is astonishing that the UK government has given the go-ahead – indeed has promoted – a massive expansion of housing. Half a million new homes are planned in the South East alone.
The CFRE (Campaign For Rural England) has said:
‘The Environment Agency’s own figures show that for this number of houses to be sustainable would require all the new houses to be 25% more water-efficient and all existing houses to be 8% more water-efficient. Yet 200,000 new houses have already been built in the region without any water conservation measures. Unless we can make the politicians and planners listen and re-think, we are heading for disaster here in Eastern England.’
In a letter to The Guardian, on August 9 2006, Campaign to Protect Rural England chief executive said:
‘Any attempt to define an optimum level for immigration… needs to look beyond issues of the economy and social stability, important as these are, to take into account the environment…. The UK is one of the most densely populated and built up countries in the EU and some English regions are already close to reaching the limits of their capacity to take further development without serious damage to the environment or quality of life.’
Our total usage of water just puts us inside the WWF category of mild stress, and we should regard this as a wake-up call. Along with every measure for reducing per person use of water, through metering, efficient appliances, rainwater harvesting, and reduction of pipe leakages, we should address the problem of population.
The UK has until recently been one of the most resilient economies in the world. Over the last 100 years, it has survived two world wars, staged spectacular economic recoveries, been blessed with energy resources, and evolved from manufacturer to the world into a service economy. But the position in which it now finds itself looks bleaker.
The UK is no longer a net exporter of oil and gas, and though rising prices will in the short term mitigate the impact of this reversal, its trade deficit in goods and services continues to widen. Domestic energy substitutes are unlikely to be able to support current levels of economic activity, and the insecurity of energy imports and import prices is already evident.
Of all the problems that we have to face right now the convergence of Peak Oil, Climate Change and economic instability are probably the most crucial issues we face.
All these problems are merely symptoms of a single, deeper underlying problem. They are symptoms of a species and a way of life that have grown beyond the ability of this planet to supply enough resources or to cope with our inevitable waste products. This growth is seen in the human population, currently surging through 6.6 billion people worldwide. It is also seen in our economic and industrial growth, with its emphasis on perpetually rising living standards and increasing wealth.
The consequences are already clear - our planet is under mounting stress from human activities, with its climate changing and its ecosystems failing. But recognition that we must act urgently to preserve our natural habitat has been undermined by persistent failure to admit the multiplier effect of human numbers. Without policies to reduce world population, efforts to save our environment cannot succeed.
The only thing that has enabled our numbers to shoot so far over the long-term carrying capacity is the planet's one-time gift of fossil fuels. This has also enabled our underlying destruction of the biosphere.
The global human population before the discovery of oil was about 1-billion. Today it is about 6.6 billion and rising. Without oil, the earth will only support about 2-3 billion, and only if we stop desecrating our environment right now. We cannot continue to feed an expanding global population indefinitely.
The uncomfortable truth is that the impact on Earth's biosphere of a projected 9 billion people living at a desired higher standard of living in 2050 would be fatal for the planet in terms of greenhouse gas emissions alone.
Given the fact that our world's carrying capacity is supported by oil, and that the oil is about to start going away, it seems that a population decline is inevitable. The form it will take, the factors that will precipitate it and the widely differing regional effects are all imponderables.
Populations in serious overshoot always decline, though actually, it's a bit worse than that. The population may actually fall to a lower level than was sustainable before the overshoot.
The reason is that unsustainable consumption while in overshoot allowed the species to use more non-renewable resources and to further poison their environment with excessive wastes.
However it is important to recognize that humanity is not, overall, in a position of overshoot at the moment. Our numbers are still growing (though the rate of growth is declining).
However, we are getting obvious signals from our environment that all is not well. If the carrying capacity were to be reduced as our numbers continued to grow we could find ourselves in overshoot rather suddenly. The consequences of that would be quite grave.
So here we have a huge, complex, brittle system built on the foundation of a depleting, non-renewable resource and depending on a damaged environment with diminished carrying capacity. If this system receives a series of shocks (such as repeated local interruptions of its energy supply) the resulting failure cascades can disrupt the organization of the system to such an extent that the cohesion provided by its interconnections fails.
Ironically those connections themselves become the pathways that spread the failure to other parts of the system.
What has all this theorizing to do with population?
Because we are now a global species with a global civilization, continuing growth of our numbers depends on the continuing growth of our civilization. Humanity does not grow through demographics alone; there must be a sufficient level of food, shelter, energy and medical care available. All these factors will be put at risk globally within the next two decades due to the loss of oil and our ability to keep people alive will decline.
Food production and distribution will be hampered or in some cases made impossible, and due to the damage of soil and water local agriculture will prove very difficult in some places. If medical care erodes, so will infant mortality and longevity. The erosion of urban sanitation systems will have an identical but greater effect. Across the world the effects will be highly variable, with some places like the United States and the United Kingdom suffering from the catastrophic decline in net global oil exports that is now underway. Other countries like those at the bottom of the list of developing nations will simply be too poor to compete against the developed world for the resources needed for survival. Populations will fall as a result.
This leads inevitably to the objection that such a position caps the aspirations of less developed countries and is thus morally unacceptable. Be that as it may, the facts remain: there aren't enough resources to bring the whole world up to the industrial level of the developed world and the developed world is unlikely to consent to their own voluntary impoverishment in favour of industrializing the less developed world, and attempting such an approach would increase rather than reduce global ecological devastation. There appears to be no possibility of reducing global fertility through industrialization.
What is amazing is that today’s human society views the present planetary catastrophe (to the limited extent that it considers it at all) only in terms of its impact on itself – on the current generation of human beings. From the viewpoint of future generations, Nero is fiddling as Rome burns.
According to the 2003 State of the World report by the Washington-based Worldwatch Institute, the human race has only one or perhaps two generations to rescue itself. "The longer that no remedial action is taken, the greater the degree of misery and biological impoverishment that humankind must be prepared to accept," the Institute says in its 20th annual report. Various other reports, like that of the Intergovernmental Panel on Climate Change foresee world-catastrophic conditions already for the second decade of this greatly celebrated millennium.
The authors of The Limits to Growth suggested that it may be possible to avoid the collapse, and transit peacefully to a long-term-sustainable equilibrium, that was over thirty years ago.
I fear this ‘predicament’, not ‘crisis’, because these conditions are not of recent origin and will not soon abate, may no longer be solvable by ourselves and that the change will now be forced upon us with chaos and suffering by the inexorable laws of nature.
Faith in technology as the ultimate solution to all problems can divert our attention from the most fundamental problem--the problem of growth in a finite system--and prevent us from taking effective action to solve it.
We must learn to live within carrying capacity without trying to enlarge it. We must rely on renewable resources consumed no faster than at sustained yield rates.
"If the present growth trends in world population, industrialization, pollution, food production, and resource depletion continue unchanged, the limits to growth on this planet will be reached sometime within the next one hundred years. The most probable result will be a rather sudden and uncontrollable decline in both population and industrial capacity." 
As for man, there is little reason to think that he can, in the long run, escape the fate of other creatures…….. During ten thousand years his numbers have been on the upgrade in spite of wars, pestilence, and famines. This increase in population has become more and more rapid. Biologically, man has for too long a time been rolling an uninterrupted run of sevens.
- George R Stewart, Earth Abides (1949)
 UK Climate Impacts Programme, 2002.
 The Benfield Hazard Research Centre www.benfieldhrc.org/climate_change/sea_level_rise/sea_level_rise.htm
 Human Genome Project Information
 The Limits to Growth (1972)
2003 State of the World report by the Washington-based Worldwatch Institute
My special thanks to Paul Chefurka for his Peak Oil, Climate Chaos and the World Problematique www.paulchefurka.ca/ and to OPT www.optimumpopulation.org/ and Rosamund McDougall for their help and assistance.
"Most people occasionally stumble over the truth, but most pick themselves up and continue on as if nothing ever happened."