This ECO discussion paper sets out to raise the profile of this crucial subject on the political agenda and to contribute to the debate which seeks meaningful and practical policies for those engaged in the politics of ecology.
Human population could be the single most important factor in the impending ecological crisis. This is an issue which must be addressed by any campaign to raise the profile of political ecology.
There has been much emphasis on developing ecologically acceptable technology. However, no technology is entirely benign; the impact of human activity in relation to the carrying capacity of the ecosystem is the product not only of the type of technology used but also of human numbers and per capita consumption. Action is needed urgently, therefore, both to restrict individual consumption and to control the number of individuals.
In the short term per capita consumption must be reduced drastically. For many developed countries this may be the only way to reduce human impact on the ecosystem fast enough to achieve anything approaching sustainability in the immediate future. On the other hand, for the very reason that population changes are slower to implement, it is vitally important that the matter is addressed and action taken to alter the course of this juggernaut as soon as possible.
Population control is an emotive subject impinging on personal freedom. This makes it politically difficult and may explain why it rarely features on the political agenda of western countries or does so for the wrong reasons. Nevertheless, in western countries with high per capita consumption, the amount of resources consumed and pollution produced by a single individual is equivalent to the impact of a large number of people in the poorest countries. Moreover, despite their material affluence, many western countries would be hard pressed to feed their present populations even at a subsistence level using only their own renewable resources. The issue of sustainable population is universal.
The subject is relatively complex with many interacting issues. For political action to achieve real long-term benefits, we need a clear understanding of the way human activity affects the ecosystem. We also urgently need quantitative targets for the level of individual consumption and the population that can be supported. Though these will necessarily be imprecise initially, the concepts must be clear so the numbers can be adjusted and the targets refined as our knowledge increases. This paper presents a perspective as background for rational debate of the subject on a common footing. It is clear that an agreed ethical basis for clearly defined targets and positive control of population is needed. Ongoing progress will require not only political will but also regular review, together with research and development (R&D) in order to assess progress and refine objectives as time passes.
Having got this subject onto the political agenda, the second key objective is to find acceptable methods of control in order to progress sustainably towards the targets identified. It is hoped that this paper will encourage the development of ideas to this end. Debate is urgently needed to achieve the consensus necessary to put practical policies into practice.
Carrying capacity, loosely summarised as the amount of activity or population that can be supported in a sustainable manner, is a term heard frequently in ecological circles. It is indeed central to the whole ecological debate, but its full significance cannot be conveyed by a simplistic definition.
On a physically finite planet, the reserves of materials and energy are also finite. The laws of thermodynamics show that for any process to occur, a natural driving force based on low entropy matter/energy is required. This applies to all forms of life and particularly to human economic activities.
The principal long-term thermodynamically useful input is high-grade energy from the sun. Conventional nuclear power (fission) has outputs which cannot all be handled by the ecosystem; the potential for major accidents has already been demonstrated. Nor is there any certainty that fusion could ever be safe and controllable. Thus renewable energy is limited to that available directly or indirectly from solar energy in the form of photosynthesis, solar cells, wind power, wave power and various other technologies, though even these are not all free from environmental side-effects. On a practical timescale, a few other sources including geothermal and tidal energy can effectively be considered renewable.
The sink to accommodate waste from economic activities is also limited in the amount or the rate that material can be assimilated. Thus the total activity of all living systems, including but not restricted to humanity and economic activities, cannot in the long term exceed either the limit of available free energy throughput or the ability of the ecosystem to convert waste.
The current ecological crisis is a result of excessive human activity, threatening to suffocate the ecosystem and ultimately itself. It remains to be seen whether depletion of resources and habitat or pollution is the most immediately limiting factor.
The limit to human activity is a function of the number of people, the amount of activity per person and the specific resources used or resource inefficiency of each activity.
There are practical and theoretical limits to the efficiency with which economic activity can be carried out. Too large a population will eventually reach the limiting carrying capacity however low the level of per capita activity. Likewise, however small the population, a large enough per capita activity will also hit the limit. Therefore both specific consumption per individual and human numbers inevitably contribute to the impact of human activity and it is necessary to tackle both of them in order to secure the long-term habitability of the planet.
For example, based on available resources and pollution assimilation capacity, we could evaluate the sustainable consumption per person for a region to be self sufficient. A considerably higher per capita consumption would be sustainable if the population were correspondingly smaller. In principle a larger population could be sustained at a lower per capita consumption. Unfortunately, the population of many western countries probably already exceeds what could be sustained in any manner without the use of non renewable resources.
It is therefore evident that carrying capacity is not a single value but an infinite set of limiting combinations of population and per capita activity.
Seen in this perspective, it is hard to argue for the maximum sustainable population/minimum consumption per capita approach to carrying capacity. This would condemn many to physical misery and almost all to unacceptable austerity. Many worthwhile human activities inevitably do consume some resources. A large human population with consequent overcrowding increases the probability of large-scale conflict, disease and starvation. It also decreases the latitude to respond to "natural" hazards such as non-anthropogenic climate change, epidemic, earthquake, etc, and it conflicts with the interests of many other species. In many cases these events only become "disasters" when problems caused by natural hazards are exacerbated by overpopulation. Yet it is almost always only the natural hazard to which a disaster is attributed.
From a non-anthropocentric point of view, but also ultimately out of human self-interest, biodiversity needs to be maintained. Human activity puts pressure on habitats and causes pollution, adversely affecting many species. Fewer people and less economic activity encourage biodiversity.
In addition to considerations of pollution and material and energy resources, lack of land area must also be considered as a potentially limiting factor. This is a particularly urgent problem and its effects may become critical long before geologically stored fossil fuels have been exhausted.
It would be extremely foolish, even with an acceptable balance between population and specific activity, for humanity to treat the carrying capacity limit as its target. The earth would be a much safer, more diverse and less overcrowded place if we could keep our activity well below the absolute maximum.
Below a certain population, human life would also become very hard and material living standards likely to fall to a rudimentary level. Human impact on the environment might cease to be an issue but we would lose the economic benefits of shared knowledge and appropriate specialisation or division of labour. Given the choice, it is unlikely that many people would accept this option which would thus be de facto unsustainable.
These considerations lead to the concept of optimum carrying capacity. This will not be an exact numerical value and it will change as knowledge and priorities evolve. Rather it should be seen as a band of acceptability. Nevertheless, any coherent philosophy about a sustainable future must address the issue, examine the factors involved and attempt to put upper and lower bounds on the band. This would allow us to set practical targets to aim for and to develop institutions to bring and maintain numbers within them.
The objective function to optimise carrying capacity includes many variables which differ according to location, time, and other factors. Developments in technology will continue to change the resources consumed and the wastes generated by a variety of activities. This will alter their optimum levels, even in a truly sustainable economy.
On a global level, carrying capacity requires that the earth lives within its sustainable thermodynamic budget with all activities limited to levels compatible with a healthy ecosystem. This imperative, however, should not cause us to seek strict homogeneity, which is in itself contrary to the principle of diversity. Carrying capacity is a multi-dimensional issue with different scales being appropriate, depending on the nature of activity involved.
Trade allows carrying capacity to be transported between regions but the transport itself depletes resources. Wastage is clearly minimised if most consumption is sourced relatively close to the point of use. On the other hand, for some activities, economy of scale does apply to resource efficiency and waste minimisation. Particularly where long-life products are involved, carrying out these activities at fewer locations would outweigh the transport penalty.
On balance, any given area, region or population should not be a net carrying capacity importer. In other words it should not be allowed overall to "borrow" more carrying capacity from other areas than it "lends". In practice, cities are inevitably net importers of food-growing capacity; any workable definition of what comprises a region must encompass both cities and the surrounding land necessary to support them. This must consider, for example, such issues as the transport of water from Wales to cities in the Midlands.
We need to develop a consistent framework within which to assess matters of carrying capacity transfer. This would enable rational decisions to be taken about trade and protectionism both for agricultural produce, manufactured goods and natural resources such as water. It would also provide a basis for tuning the market mechanism by appropriate pricing and, whilst they last, for determining the cost and ownership of non-renewable resources including fossil fuels.
In general, activities that cannot be supported sustainably on locally derived resources should be carried out only at very low intensity, whereas non-polluting activities based on local resources may be less constrained. The extent to which these activities are necessary or desirable for a good quality of life influences what population levels are appropriate.
On first sight, this analysis may appear unduly complex. However, it becomes little more than common sense once the basic paradigm shift has been made from the concept of society having no obligation to consider its effects on the local and global ecologies that support it, to the vision of society as ecologically responsible. Sustainable human affairs on a finite planet must involve conceptual appreciation that some resources are utterly unrenewable and the possible throughput of those that are renewable is still strictly limited. It follows that future aspirations must be towards optimisation rather than maximisation. We must forsake activities that make us dependent on maximum exploitation of resources, especially those that are unrenewable, in favour of making optimum use of those which are renewable. Combined with a "cradle to grave" approach to assessment of ecological impact, the rationale falls clearly into place.
The concept of an allowable, sustainable Eco Budget provides an alternative view of carrying capacity. It applies in principle to all species but humanity is the only one that consistently consumes resources and pollutes at a rate sufficient to constitute a serious global ecological threat. Indeed, the interactive nature of ecosystems is such that for many species their lack of activity would be as much of an ecological threat as increased activity.
By considering the total resource and pollution assimilation capacity available, we can postulate an average Eco Budget per individual which enables us to visualise what living in a sustainable world or local community would entail. A number of investigations along these lines have been made but most have treated existing or predicted population levels as pre-determined. The sensitivity of the Eco Budget to population is crucial.
For example, evidence suggests that in historical times the population of Britain peaked several times at around 5-6 million before growing dramatically to around 50 million in the two hundred years up to the mid 20th century. It is probable that the maximum sustainable population for pre Industrial Revolution society was less than 10 million. It is not yet clear how much this could be increased by modern technology if not supported by non renewable energy and food imports. What is clear is that to provide for the present population in a sustainable manner would require a drastic reduction of per capita consumption and a quality of life that many people would find unacceptably austere.
Once quantified, this approach will enable us to understand the type of lifestyle that could be sustained at a given population level. Conversely, it will be possible to determine the population levels compatible with given lifestyles and their long-term rates of resource consumption. Such insights should make it possible to develop appropriate targets for population and to temper people's expectations to reality. Thereby we can develop targets, both population targets with an understanding of the sustainable lifestyles they permit, and targets for per capita resource consumption with an understanding of the constraints they impose on sustainable population levels.
Human activity has reached a scale where conscious human decisions affect the environment upon which the whole ecosystem depends. It is clear that decisions need to be made on ethical issues and the overall scale of activity governed by these rather than by unfettered market forces. The ethical debate must consider population, consumption and living standards in relation to carrying capacity, setting out from the premise that the ecosystem comprises a multitude of species, not just homo sapiens.
Populations in most western countries already exceed their carrying capacity. Indeed this may be the case for many developing countries too. Rich countries are "borrowing" carrying capacity from poorer parts of the world whilst their own industry and agriculture rely heavily on non-sustainable energy consumption. For example, per capita fossil fuel consumption of Western Europe is several times that of many less developed nations and that of North America is nearly twice as much again. Per capita meat consumption in Western Europe and North America is more than ten times that of many poorer countries. This imbalance of consumption per individual means that every extra individual in a prosperous country consumes the resources needed to sustain a considerable number of people in a poor country. Likewise every individual less in a rich country frees resources sufficient for several in a less developed region.
It is impossible to accept such inequitable distribution as ethically acceptable and hard to deny those in developing countries the living standards enjoyed by the richer nations. This suggests a moral obligation on the part of wealthier peoples of the world both to reduce their per capita consumption and to reduce their population.
In addition to its more immediate implications in terms of pollution, the effect of fossil fuel consumption is to borrow carrying capacity from the past and deny it to the future. It cannot be acceptable to draw down geological capital (eg fossil fuels) at the present extravagant rate, thereby denying responsibility for the needs of future generations or for the harm done to other species. A fully satisfactory method of allocating resources between the needs of present and future remains to be agreed.
A controlled enterprise/market system has an important role in providing incentives for people to contribute to their economic well-being and in dealing with allocation of resources at a local scale. Indeed, such a market system is likely to be an essential part of a future ecologically sustainable society. Nevertheless, an unrestrained market system on its own is extremely unlikely to lead to long-term stability and a satisfactory overall scale either of economic activity or of population.
Therefore it is essential that these crucial issues of scale are dealt with in an ethically acceptable manner at a political level.
Just as achieving an appropriate scale of economic activity cannot safely be left to market forces alone (ref Daly H, Steady State Economics), similarly population levels must be brought under overall control whilst leaving people with as much individual freedom as is realistic.
There are several essential features of any society in which population control will have a reasonable chance of success. Policies to develop this framework could reasonably be put in place before the debate is concluded about appropriate institutions specifically to control numbers. There must no longer be an incentive for individuals to have (many) children as an insurance to provide for old age. Therefore people must live in stable communities with long- term financial security.
Individuals should not benefit financially or socially by having large families. On the other hand, the community as a whole needs some children in every generation. Therefore those who raise a responsible number of children should not be penalised relative to those who have none; in particular no policy would be acceptable if it caused children to live in greater poverty than the population as a whole.
There is some evidence that, given help, many people in poor countries with high birthrates would voluntarily reduce their rate of population growth. With more empowerment of women, more security and ready access to effective contraception this might indeed occur.
However, even a small increase in population will eventually lead to unacceptable numbers. In many western countries for example, populations are still growing slowly and if they are static or even falling it is usually because of short-term economic factors rather than a deliberate policy of reaching a long-term sustainable number.
Given a clear explanation of the problem, it is possible, but unlikely, that exhortation to voluntary restriction of reproduction will produce the desired results. Firstly it is unlikely to achieve the right rate of change. Secondly, it is likely to be undermined by a combination of a minority who refuse to conform and reluctance of the majority to make personal sacrifices for the common good when others are seen not to.
Unfortunately, by their very nature of producing less individuals, cultures which encourage small numbers of children are likely to be outnumbered by those that do not.
Almost certainly, therefore, population control will require a measure of enforcement.
The average number of children procreated per individual must be such that the population moves towards an optimum sustainable level within an acceptable time. We may need to separate the variables and obtain consensus on the need to reduce population and the rate at which it must be carried out independently of agreeing the means. This may make the medicine less unpalatable.
Because this is a highly emotive issue for many people, it is essential that it is thoroughly debated. The first steps are to make the population as a whole aware that there is a problem and to encourage discussion of possible methods to tackle it. At the same time practical policies as discussed above could be put in place to provide the necessary framework for long-term success.
Persuading both politicians and the electorate of the critical importance of population and carrying capacity will not be easy. Selling any specific proposal for population control may be even harder. Attempts to do so will continue to meet with all kinds of objections as a result of cultural and emotional barriers, refusal to make any personal sacrifice or entrenched vested interests. Objections actually expressed range from people's real concerns to a smokescreen set up deliberately or subconsciously to obscure the true reasons for not challenging the status quo.
The majority of real objections can be countered quite readily and a few of those most commonly met are considered below:
`Population control represents a loss of personal freedom and unacceptable interference with people's personal lives.'
However, by depriving them of space and resources necessary for a dignified existence, failure to act on the problem denies freedom to people in poorer communities and future generations.
`Because there is intrinsic value in human life, we should not seek to restrict the number of lives by controlling population.'
By restricting the number of people alive at one time, life will be sustainable for many more generations. The long-term aggregate number of lives will be greater and the quality of life experienced will be vastly improved.
`An ageing population requires more young people to provide for present generations when they reach old age.'
This objection is only relevant during the run down period to sustainable population levels and largely spurious in any case. Many elderly people can contribute a lot to the economy and at present we have severe problems of unemployment. A more flexible attitude towards employment and retirement would help to solve both problems. Failure to control population now will result in a much more rapid drop being forced when resource limitations really bite.
`We need more people to provide a market and stimulate economic activity.' This is one of the central myths of the present unsustainable economic system built on growthmania. Return to go and start thinking ecologically! What we need is not more people but economic and financial institutions that can serve us effectively in a steady state economy without the need for constant growth.
`It is a basic right of every person to have as many children as they want.'
If so, it is also a basic right to condemn one's own and every one else's descendants to a miserable and overcrowded existence with consequent poverty, starvation, disease etc.
`The population of Western Europe is almost static at the moment so there is no immediate cause for concern.'
Even a small growth rate leads to a large increase over time. In any case, Western Europe is already living far beyond its means in terms of carrying capacity with fuel consumption and CO2 generation, for example, several times more than that sustainable as a proportion of the total world population.
Raising the political profile of population and carrying capacity issues is only one step on the road to sustainable solutions. The conceptual framework of understanding needs to be backed up by quantitative information in order to determine limits, effects of different resource consumption, population level changes etc. Some work is already being done, largely by voluntary organisations. This work is vital for the long-term good of the community, ultimately the rightful province of public funding. Any responsible government should ensure that it is being done, that enough is being done and that it is being done soon enough.
Controlling human activity to within both the local and global carrying capacity is vital for the stability of the ecosystem and consequent well-being of many life forms, including that of humanity itself.
Clean efficient technology and moderation of individual consumption are both important ingredients of a sustainable future but activity will inevitably exceed carrying capacity if population levels are allowed to continue to rise.
Humanity has a choice. Population can be left unchecked, ultimately being limited by starvation, disease, war, and other forms of disaster. This leads to extreme poverty and misery for millions of people, continued destruction of habitat and extinction of many species. Alternatively, we can acknowledge the problem and devise more acceptable methods of bringing human numbers to a level compatible with a stable ecosystem and a good quality of human life.
It is unrealistic to expect this to happen by purely voluntary means. It is a matter of priority to establish this issue on the political agenda, obtain consensus that something must be done, determine population targets and develop socially acceptable methods of ensuring that these are met.
Population and carrying capacity are so important that government must not only acknowledge them but also accord them priority equal to or greater than other major economic issues.
The following references are recommended for further reading :
Daly, H, 1992. Steady State Economics (Earthscan)
Ehrlich, P & A, 1990. The Population Explosion (Hutchinson)
Hardin, G, 1993. Living Within Limits (OUP)
Meadows, D, et al,1992. Beyond the Limits (Earthscan)
Ophuls, W, 1992. Ecology and the Politics of Scarcity (Freeman)
Two organisations dealing with population issues are:
The Optimum Population Trust: 12 Meadowgate Urmston Manchester M41 9LB
Population Concern: 231 Tottenham Court Road London W1P 9AE
Introduction to Political Ecology: Core Principles Explained
Discussion paper : Population and Carrying Capacity (this document)
Discussion paper : Features of a Sustainable Ecocentric Economy
Copyright © The Campaign for Political Ecology. All Rights Reserved.
Published October 1995, reprinted October 1997, revised February 1999.
This page last updated: 16-March-2003