Smail identifies two irreconcilable trends of thought: first the predictions that the human population will grow to some 10 to 12 billion in 50 year's time; second, scientific estimates that only 2 - 3 billion people can be sustainably supported at a comfortable level.
He believes that within the next fifty years we must have in place an internationally co-ordinated, broadly equitable, voluntary set of initiatives to dramatically reduce population; and because it will take fifty years of consensus building, it should start now.
The age of inexpensive energy, adequate food supplies, readily available or easily extractable raw material, plentiful fresh water and readily accessible open spaces is rapidly coming to a close. On top of that, issues of wilderness conservation and space for all the co-inhabitants of earth have to come into the equation. So stabilisation of the human population will not be enough; we should be aiming for 2 - 3 billion by the beginning of the 23rd. century. However, very few organisations will state such a view.
The factors stacked against a reduction are:
However, agreement on the numbers will actually be easier than getting consensus on the ethical, political and economic restructuring that would be required. What is needed is a global fertility rate (births per woman) of 1.5 to 1.7. In other words 'stop at two', given that some women have none and some have only one. This level of fertility has already been reached in some places. What is also needed are incentives to postpone first pregnancies, with the aim of having only 4 generations per century in each family. However, reduced fertility is intertwined with very sensitive political and ideological concerns, especially gender equity, but also with nationalism, migration, inequity etc. The danger is that we lose sight of the exploding demographic 'forest' because so much political pressure is focussed on the ideological 'trees'. The result has been that large-scale economic aid and liberal immigration policies have, in unforseen ways, actually stimulated the growth of population.
Abernethy agrees with Smail except that she sees individual motivation as the main issue. Her researches lead her to the view that contracting economic opportunity gives rise to declining fertility, whereas the perception of expanding opportunities result in rising fertility. Economies which have frequent crises produce more declines in fertility; there was a 46% decline in E. Germany between 1989 and 1991, and even 50.9% from 1989 to 1994. Land hunger also creates declines.
Where certain ethnic groups are favoured by government, eg. Malays in Malaysia post 1957, the least favoured groups (in this case Chinese and Asian) exhibit large fertility declines. It seems that diminishing opportunities result in reproductive caution.
Migration is important, too. Outward migration relieves population pressure and brings back money, both of which encourage fertility to remain high. Communities without an emigration safety valve reduce fertility at a faster rate. Abernethy says, "Aid destroys the earth's early warning system", especially that aid which supports consumption and facilitates emigration; it neutralises the environmental signs that would alert individuals to limit childbearing. So she concludes that there should be provison of micro-loans on a communuity-circle basis where repayment is self-enforcing, and of contraception for those who want it.
Prof. Dyson both agrees with Smail - and disagrees profoundly. He believes that world food prospects will improve through the next few decades, and that Smail pays insufficient regard to the 'trees' (ideological goals) using over-sensational vocabulary.
He disagrees that aid and easy migration have unfortunate demographic effects, and reminds us that birth-rates are falling in most developing countries including sub-Saharan Africa. The issue is - how can we best accelerate the decline in growth-rates so that we don't go over the 7 - 8 billion mark? The focus must be avoidance of unwanted births, and increases in levels of education especially for women. Rich countries can help with certain kinds of aid, notably by ensuring that health and family planning services are set up. He quotes Malcolm Potts: ' If the proportion of OECD aid ear-marked for family planning rose from 1% to 2% or 3% then fertility decline in many parts of the world could be accelerated." Another useful type of aid is scientific help with local environmental problems.
Dyson also counters the Smail/Abernethy arguments about migration, by instancing the way in which Asians coming to Britian quickly reduce their fertility. Another example is the way in which Puerto Ricans carried modern awareness of contraception back from New York, resulting in early reductions in fertility in the island.
In conclusion he feels that Smail insufficiently addresses the issue of profligate consumption in Western countries; yet changing consumption patterns is really the main issue.
There are few, if any, frontiers left to be exploited by a growing global population, Flannery says. Australia has 'only' 18 million people but is equivalent in size to the 48 states of USA. For 50 years the Australian government has been trying to increase the population, and has predicted that by 2025 there will be 23 million, half the increase being through immigration. Between 1986 and 1996 the growth-rate has been greater than that of China, Canada or the USA. Yet Flannery believes that Australia is already overpopulated; at current levels of technology the optimum population would be some 6 to 12 millions.
In 1996 the government published a State of the Environment report which showed collapsing fisheries and depleted forests. Only 3% of the land is suitable for crop-growing, and of this, much is degraded; marginal land is being overexploited for wheat exports. There is a huge water security problem because of the great variability of rainfall. There is also a great loss of biodiversity, with ecosystems in collapse.
Australia is a very urban society with very large air pollution problems. There is great tension now regarding immigration (much of it of an ugly racist nature) and therefore there is a need for the issue to be put in the context of a national population policy which is based on an optimum population size for the country.
Grant reminds us that Smail's target population of 2 - 3 billion was 'normal' in 1950 and yet it seems so outrageous compared to the projected total of 10 - 12 billion - a good example of our ability to forget and adapt. Where there is concern it centres on declines!
He wishes only to corroborate the thesis that a population turnaround is vital and points to the huge imbalance which started in the 1950s in the third world between falling mortality helped by agricultural revolutions (at the cost of the environment) and continuing high fertility. The price was the loss of a dream - possible for a moment - of creating a world where there was enough for all.
He gives three examples of the impact of demography on human well-being:
Hartman is unhappy with Smail's forcast for the end of the next century because birth rates are dropping much faster than predicted. She is also very opposed to the Abernethy thesis that aid and liberal immigration policies encourage third world people to reproduce. And she interprets Smail's reasoning as 'The poor are poor because there are too many of them.' She reminds us of the crippling debt burdens and widening disparity between rich and poor countries.
She quotes Patricia Hynes in questioning the formula I = PxAxT, wherein Smail and so many others see humans only as a negative impact on the environment, and she gives examples of humans enhancing nature. Smail is also criticised for not discussing the way choice of technology is politically and economicalluy determined. "What if," she says, "...weapons cash went into alternative energy, ...and corporations had to bear the cost of polluting?" The current environmental crisis is seen by Hartman as much more about the refusal to curb corporate profits and overconsumption by the rich, or to redirect research effort to sustainable technologies.
Yet she endorses the ecological footprint concept of Wackernagel and Rees and thinks it far superior to that of carrying capacity. (Unsure what the ideological difference is which she sees in these terms. Ed.) She defends scientists who take no stand on the issue since there is too much uncertainty. Smail's reference to the human propensity to excess fertility is rejected and we are reminded of all the coercive ways in which women's fertility has been restricted - seeing this as the grim reality of his 'balance' between reproductive rights and responsibilites. In countries like Bangladesh, the emphasis on demographically-driven population programs has led, she claims, to poor treatment and diversion of resources from the primary health care which sets the stage for the transition to low birth rates.
Her final criticism is that Smail allies himself to groups in the USA such as ZPG (Zero Population Growth) and CCN (Carrying Capacity Network) which seek a moratorium on immigration, while ignoring the real villains - the business leaders who oppose environmental regulation - and while poor immigrant communities suffer disproportionately from environmental toxins. Worse, Smail cites Garett Hardin, whom Hartman regards as a racist and eugenicist.
Haub's contribution is as a demographer. He is worried by current dwindling concern about population growth. He supposes that because birth rates have come down dramatically in some developing countries, people think that the population crisis is over. He assures us it is not. The average fertility rate in developing countries has come down from 6 thirty years ago, to 3.4 (or 4.0 when China is removed from the calculation). So we are only halfway to replacement - that is 2 children per woman.
He regards as a serious error the fact that, of the UN's three projections of population, only the medium gets attention because it seems 'most likely'. All three projections assume that birth rates will fall in poorer countries as they develop economically, as happened in industrial countries. But we cannot be sure that this will happen.
Every country is different, especially in religious and social customs. Fertility decline may slow, or stop at still high levels. In India it seems that the switch from demographic targets to reproductive health (1996) has resulted in fewer acceptors of family planning. So we should have little confidence in projections. UN projections in 1992 ranged from 4.36 billion to 28 billion for the year 2050 - the difference being produced by a quite modest difference in assumed future fertility. In China for example, if liberalisation goes on apace, the fertility rate may rise to what couples prefer. Or will death rates from AIDS be the force which slows population growth - in Africa, for instance?
Lamm essentially agrees with Smail, but sees the need to be realistic in terms of the political process. He quotes Mayor La Guardia: "A politician can't be so far ahead of the band that he can't hear the music."
A critical mass of conventional media, public opinion makers, and conventional politicians has to be convinced before political change can occur. Environmental doom-saying has been proved wrong time and again as new technologies have come in (but of course may prove true in the future); such wolf-crying has not helped public confidence.
He agrees that there is urgency, but public policy is evolutionary and should not be short-circuited. As an example he cites the liberalising of abortion law in the USA - driven through the courts, and still, thirty years later, not settled democratically. He believes that the political agenda for supporters of Smail must be for availability of family planning both domestically and internationally. Women must be educated. Countries should be pushed towards having a demographic policy just as they have an economic policy. But reduction of world population cannot be on any political agenda. Politics is about much shorter-term projects.
Lutz's is another highly critical response. Smail's wish for humanity to "err on the side of prudence" is endorsed, but with the question - what is prudent? Lutz sees nothing but misery in the violation of individual human rights that might be involved in realising Smail's "collective reproductive responsibility". He wants a refocussing of development policies to emphasis education of young women, which, he believes, will lead to sub-replacement fertility in the long term.
The population explosion has really been caused by 'deficit mortality' and excess longevity'. No-one would want to reverse these trends. Historically the gap (population growth) between birth rates and death rates was a gradual process, but after World War II, intervention in the third world resulted in precipitous death rate reductions, leading to a very large gap between this and birth rates. Reproductive behaviour, deeply embedded in cultural and religious norms, changes very slowly.
He asserts that the process of population stabilisation has begun. There is the example of Mauritious where after WWII there was rapid mortality decline and then very high population growth. In the space of the 7 years to 1965 fertility rates fell from 6 to under 3. But this had been prefaced by near-universal female literacy. The contrast is Kenya where family planning programmes failed to affect the high fertility rates - a failure due largely to low female literacy.
The fertility transition, he claims, has started all over the world and there are strong indications that fertility will continue to decline. His Institute predicts that world population will not double again in the next century. It is likely that in the 22nd. century world population will shrink. He makes a strong case for female education - in its own right, for delaying marriage, changing values from quantity to quality, enhancing the community's ability to cope with environmental damage and giving added status that allows women to pursue their own fertility goals. It is a win-win situation. In conclusion he deplores mankind's record on trying to achieve collective, supposedly benficial, ends. He would rather leave it to educated individual choice.
Myers regrets that so few scientists are prepared to speak out about population in the way that Smail has done. However he considers Smail may not be pessimistic enough.
He gives sub-Saharan Africa (where he has lived and worked for 24 years) as an example of a country where people have grown poorer and hungrier since 1960 to the point where one third are semi-starving, yet where numbers are expected to increase from 605 million to 1.8 billion by 2050. He believes that desertification and water shortages will increase leading to some 100 million being obliged to live off food aid by 2010. These problems are likely to be exacerbated by freak weather conditions and the siphoning of wealth away from agriculture to escalating military activities. Unless this region can double grain production and halve population growth, then famine on an unprecedented scale will result.
For the world as a whole he cannot see how the predicted increases in per capita consumption (especially if developing countries manage to significantly increase their citizens' standard of living) alongside the increases in numbers, can be supported by the earth. He recognises the technological potential (Factor 4) described by Weizacker and Lovins, but reminds us that so far technology has tended "to increase rather than reduce environmental harm".
Parsons broadly endorses Smail but offers some further ideas:
a) First he shows that populations are not 'seemingly uncontrolled but actually controlled by a multitude of influences, usually resulting in lower reproduction rates than the biological potential. Further, government decisions over a whole range of policy areas do influence the trend of family size.
b) While it is true as Smail says that population explosions owe more to lowered death-rates than to increasing birth rates (while countries undergo their demographic transition) there is a substantial part of this transition where birth-rates do go up.
c) He offers a definition of an Optimum Population - or rather, quasi optimum: "...a population size that is reasonably acceptable to a democratic society and which the environment can sustain as far into the future as can be foreseen."
d) He endorses Smail's idea of "births tending to expand to fill the perceived socio-economic space", and sees it in operation where militaristic groups define the space they think they ought to have in expansive terms. He regrets that discussion of such population competition (between groups and states) is taboo.
e) On the question of balancing rights with duties, he does have a slight quibble with Smail's emphasis on equitable distribution. He believes that there is much 'damaging loose talk' on this head. He says 'surely it is not implied that everyone, everywhere, is entitled as of right to an equal share of "the world's" resources wherever these happen to have been situated through the evolutionary process, and no matter how the claimant's group has behaved within its own sub-ecosystem. If it is, it is the Tragedy of the Commons writ very large indeed.' He also raises the whole question of the responsibilites of health professionals, and their role in reinforcing the population explosion. Should a new medical (ecological) ethic aim to minimize the total of human suffering?
In conclusion he believes that in this politically fragmented world where even EU countries cannot agree on fish-catch quotas, global agreement on population quotas is utterly unrealistic. He supposes that while we must work for a more just world, countries that can manage it may have to 'batten down the hatches' and 'go it alone or in the company of those few others that see the writing on the wall and do likewise'. The management of international migration seems to be the litmus test for the future.
The Pimentels enthusiastically endorse Smail, but suggest that optimum global population should be even lower than his 2 to 3 billion. Set against this view is the stark fact that, based on current growth rates, the USA population is projected to double in the next 60 years to 520 billion. (In later correspondence with ECO they amend this to 75 years, counting legal, but not illegal, immigrants. In the short time since original publication, the USA rate of increase has declined from 1.1% to slightly under 1.0%)
With two billion humans already malnourished, they identify food production as the looming crisis. Such production depends on ample supplies of fertile land, fresh water, energy and natural diversity. As population grows the amount of these resources available to each person must decline. Yet over the past 40 years some 30% of cropland has been lost through overuse, followed by wind and water erosion. Some of the loss has been made up by clearing forests. Water resources are under great stress as growing cities and states increase their withdrawals leaving some rivers only a trickle by the time they reach the sea. The authors go on to examine supplies of fossil fuel energy used to maintain food supply. The USA - already importing 50% of its oil - is likely to exhaust all its oil reserves in 15 to 20 years.
The promise of new technologies cannot double the world's croplands or provide unlimited availability of the vital natural resources that sustain agriculture. Biotechnology that started 20 years ago has not stemmed the decline in per capita food production.
Although he agrees that human numbers should go down, Swaminathan regrets
that Smail did not address two key issues:
a) the unsustainable life-styles of more than 1 billion people;
b) the utter poverty and despair of another 1 billion.
He strongly believes that we have to change our mind-set away from feeling a duty to bring children into existence, to a duty to give them happiness. He cites two very different states in India where in one (Kerala) greater gender equity, good education (90% literacy), low infant death rates and good family planning programmes have led to very low fertility rates (1.7). He sees such enlightened policies as key to population stability and reduction. He looks at the world food situation and sees Malthus's predictions - staved off by technological advance until now - coming true. China and India may have to import 240 and 60 million tons of grain respectively by 2030, and Swaminathan wonders how industrial countries will be able to produce such amounts for export without further damage to the environment.
India's national population policy aims for a total fertility rate of 2.1 by 2010. To help achieve that his own committee recommends a village/town approach with social/demographic charters set up by people themselves.
In conclusion he believes that 'if population policies go wrong nothing else will have a chance to succeed'.
Re-Feng sketches the differences in attitude to population growth in developing and developed countries, the former sensing the negative impacts of overpopulation in every aspect of daily life, the latter not seeing the problems because in general the standard of living is good. But in reality the problem is a global one concerning everyone, and Re-Feng is pleased that Smail emphasises this, alerting us to the rates at which vital natural resources are being used up.
The affluence of developed countries has hidden their population problems; whatever they lack, they can import. Therefore she proposes that population control policies should be carried out in these countries as well as in developing countries. In significant ways this would help the efforts in developing countries, in contrast to the present situation where for example, some Chinese people emigrate to western countries to escape policies limiting family size - policies which are popularly (out of ignorance) considered neither necessary nor desirable globally. The view is fostered that in a 'rich' and 'free' country one can have as many children as one likes.
She goes on to consider the human rights issue - "the basic right to decide freely and responsibly the number and spacing of one's children". This part of the 1984 UN Declaration of Human Rights is widely interpreted to imply that reproductive rights are inviolable, and stands as a challenge to any birth-control policies. So she endorses Smail's wish to find a balance with "a person's (biological) right to have children....mediated by his or her (social) responsibility not to have many". Thus it is vital that all countries take a firm stand to stabilise and reduce the human population, or, she says, "the future will bring poverty, misery and war".
Wallace endorses Smail's assertion that the earth can only adequately sustain some 2 to 3 billion people. He expands on the multidimensional nature of population/environment problems and regrets the number of unidimensional specialists who look at the problems we face just in that specialised way. We have arrived at where we are because of decisions by political leaders, businessmen and consumers, spurred on by technologists and economists; all providing us with a rosy view (material comforts) from what is an evolutionary promontory. Nearly all the specialists, of whatever discipline, who advise such leaders are unidimensional in their understanding; academic life forces them to be so. Yet every 'advance' in modern life has an effect on some other facet of social or biological life, and 'solutions' to problems also have such effects. These simplistic unidimentsional 'solutions' are not adequate for the environmental/societal problems confronting us - that promontory from which we are in increasing danger of falling.
We must act with the utmost caution and prudence . Much of education should become environmental education - indeed an "exercise in environmental literacy".
Westoff first questions why the huge problem of population growth is so invisible. The foremost reason is that it cannot be indicted as the chief villain for environmental destruction - per capita consumption levels and particular technologies are the immediate suspects. So population policies, if they exist at all, call for lower fertility as a measure of prudence but with no urgency. While very few argue for increasing the rate of growth, there is some concern, albeit muted, directed at the problems of an aging population. In short, population growth seems to affect everything but is seldom held responsible for anything.
Other reasons are:
Willey declares his complete agreement with Smail and deplores the fact that those who disagree with the often apocalyptic conclusions of pherologists (students of carrying capacity) rarely provide detailed rebuttals. He offers some additional calculations based on the three key criteria best suited to quantifying the sustainability equation: use of energy, emissions of CO2, and the amount of ecologically productive land.
World energy use. In 1994 this was 15 terawatts. Paul Ehrlich thinks that the world could tolerate 9 terawatts, but would prefer 6 terawatts for safety. In a scenario for narrowing the gap between per capita use in the rich world - 7.5 kW - and that in the poor world - 1 kW - John Holdren worked out a fair share of 3 kW per person (at the most efficient use of technology to yield a good standard of living). But this would mean global use rising to 30 terawatts as population grows.
Carbon dioxide emissions. Scientists advising the IPCC believe that a 60% to 80% reduction of the 1990 global emissions (22.3 billion tons) is required to stabilise atmospheric CO2. So the maximum we should be emitting is 8.9 billion tons, which is 1.4 tons per person per year - decreasing as population rises. This figure is contrasted with 12.32 tons in Norway and 6.24 in France. The current averge is 4.24, and is probably what we would need to use to giver everyone a satisfactory standard of living assuming much more efficient technologies than we currently employ.
Use of productive land. Willey uses the estimate of 8.9 billion hectares of ecologically productive land, of which about 1.5 billion ha of the total is wilderness (biodiversity reserve, carbon sink etc.) leaving 7.4 billion ha for humans. Since 1900 the ecological space per person has declined because of population growth from 5 - 6 ha to only 1.5 ha. He asks what amount of productive land per person would be adequate to deliver a satisfactory standard of living and believes that it must be at least 2 ha, and 2.5 ha if we wish to supply energy from renewable resources.
The sustainability equation: I = PCT. In the preceding paragraphs the totals thought to be sustainable for I (environmental impact) and for C (consumption) have been identified. P (population) can be counted. This leaves T (technology) as the big variable, and very controversial. But in Willey's calculations the beneficial effects of improved technology have already been allowed for. He then presents the I = PCT equation quantified for each of the 3 criteria. The equations show that only a global population of 3 billion can be sustained in the case of energy use and ecologically productive land; and only 2 billion in the case of CO2 emissions.
Another key criterion for Willey is the degree of liberty and mobility that people want. He echoes Jack Parson's classic question: "Would population control reduce individual liberty more than unrestricted population growth?", agreeing with him that population control is needed in order to preserve individual liberty. He goes on to suggest some specific target populations for the world's major regions. He believes that in Europe and Japan a reduction in the number of consumers could make a bigger and quicker reduction in total consumption than could efforts to reduce per capita consumption. He stresses the importance of migration by citing Switzerland where net immigration could raise population from 7 millions to 10 millions in 50 years, but where, with emigration and immigration in balance, the population would reduce to 5 million. Reduced numbers in developed countries would improve life in almost every way for the indigenous population and would free up 'environmental space' for use by poorer countries.
He welcomes the fact that the commentators are broadly international, represent many different fields of experience, and that their views range from very supportive, through to strongly critical. They are able to elaborate on specific problem areas, and the assertions of one are often dealt with by another. He explains that he originally wrote his paper as an introduction to a college course and meant it to be something of an exhortation. Students, however bright and however aware of environmental problems, seem unaware of the exponential nature of recent human population growth. He recognises that he did not delve much into justice issues (the growing gap between rich and poor) or into technological possibilities for taking pressure off resources, but he wished to stick to the main issues. He claims no special expertise - only a willingness to stick his neck out on this issue.
His thesis: The case for a dramatic reduction in human numbers over the next 2 or 3 centuries is presented as a testable hypothesis. Even if the figures presented (eg. 10 billion before stabilisation and 2 to 3 billion for the optimum sustainable number) are both proved quite off target by subsequent research and events, the hypothesis still stands so long as the first figure exceeds the second. He hopes his hypothesis is wrong and that rapid slowing of growth and huge improvements in technology will result in earlier congruence between the two figures. But it is time that the burden of proof shifted to the 'cornucopian optimists'; they must show that the earth can withstand, without damage, another couple of centuries of growth in human numbers. In publishing his thesis with the support of others he hopes to make it easier for political and economic leaders to speak out on this matter without feeling they are committing political suicide.
Consumption and equity: He acknowledges the serious need to address this aspect. For him, it means that developed countries have an overpopulation problem of significant proportions - that, as part of cutting their total consumption levels they will have to reduce the number of consumers. He considers a possible scenario contrasting India and the USA, in which the first has a 100% improvement in standard of living, and the other achieves a 50% cut in resource-waste: the goal of greater equity is approached but, with the predicted population growth in both, the benefits to the earth are negated. In sum, even worldwide technological efficiencies and much reduced per capita consumption in developed countries will not be enough to give everyone a much better quality of life. Overall population numbers have to be reduced as well. We must not forget, while striving for greater equity for people alive now, to think of the equity for future generations, and for other life forms - biological equity.
Predicting numbers: The demographic transition theory is fraught with uncertainty, especially as we and the earth try to cope with increasingly severe economic, environmental and societal problems. Will fertility rates fall to replacement level at some point or will they stabilise at levels that just keep population increasing? It will be even more difficult predicting what will be 'sustainable' or 'optimal' as earth's ability or inability to cope with abuse manifests itself in unpredicted ways.
Measures: Smail stresses that at no point does he advocate 'top down' or target-orientated measures for population reduction, but voluntary, flexible, educational and locally focussed measures, co-ordinated internationally to deliver accurate, scientific information. He acknowledges that by concentrating on global population he has sidestepped the un-discussable area of immigration. At the global level all (!) one needs to discuss is fertility rates - mortality rates being also un-discussable at any level.
Finally he describes population in the C20th as 'out of control' and our task as being to bring it 'under control'. Yet 'control' is a word, he admits, with very negative connotations, although what he means is the voluntary exercise of restraint. He notes that in the main those who agree with his thesis are ecologists and/or evolutionary biologists, and older, even retired public policy officials. His view is reinforced that population issues are imensely complex and connected with a great number of other problems currently faced by humanity, in mutually reinforcing ways. Indeed he holds unchecked population growth responsible for a great deal.
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This page last updated: 3-September-2001