Other Literature. Precis and comments on publications relevant to population growth and migration

Introduction

On this page we will, from time to time, draw the attention of readers to important publications. Prior to June 2004, the only publication mentioned on this page was by N. Myers (our presentation on that publication is retained at the end of this page). Publications are arranged in the order in which the accounts of them were placed on the page, the most recent at the top. Beginning in April 2007, the date of posting of items onto the web will be given.

Contents

Harte, J. (2007). 'Human population as a dynamic factor in environmental degradation'. Posted 14th August 2007.
Carr, D. L, Suter, L & Barbieri, A. (2005). 'Population dynamics and tropical deforestation: State of the debate and conceptual challenges'. Posted 15th May 2007.
'Return of the Population Growth Factor. Its impact upon the Millennium Development Goals' (Report of Hearings by the All Party Parliamentary Group on Population, Development and Reproductive Health). Posted beginning of April, 2007.
'Driving the human ecological footprint' (a 2007 paper by Dietz, Rosa and York).
'Immigration and Ethnic Change in Low-Fertility Countries: A Third Demographic Transition' (a 2006 paper by D. Coleman).
'Imagine earth without people'. Article in The New Scientist (2006).
'The Tragedy of the Commons - and Human Population Growth' (papers by Hardin, 1968, and Soroos, 2005).
'Climate science and famine early warning' (A paper by Verdin 2005).
Amy Chua (2003) 'World on fire', and N.C. Vaca (2004) 'The presumed alliance. The unspoken conflict between Latinos and Blacks and what it means for America'.
N.Myers (2001). 'Environmental refugees: a growing phenomenon of the 21st century'.

Harte, J. (2007). Human population as a dynamic factor in environmental degradation.
Population and Environment 28: 223-236.

This paper provides a comprehensive analysis of the linkages between human activity and environmental degradation. Harte begins with a brief summary of the effect of mankind on the environment:
“For the past several centuries, humanity has been increasingly polluting air and water, altering Earth's climate, eroding the soil, fragmenting and eliminating the habitat of plants and animals, and depleting the natural bank account of non–renewable resources. Of especially great long–term concern, we are as a consequence simultaneously degrading the capacity of natural ecosystems to regenerate or maintain renewable resources and ecosystem services, such as the provision of clean air and water, the control of flooding, the maintenance of a tolerable climate, the conservation and regeneration of fertile soil, and the preservation of genetic and other forms of biological diversity”.

The stage is set by the famous 'IPAT EQUATION', I=PAT:
“Environmental impact = (Population size) × (per–capita Affluence level) × (impact from the Technologies used to achieve that level of per–capita affluence)”.

But Harte points out — and this is central to his analysis — that we must not take the equation too literally: Population is not a 'linear multiplier'. That is, we must not think that if we hold A and T constant, environmental impact (henceforth EI) grows in simple proportion to population size, because it does not do so. There are several reasons for this.

First, with increasing population size, the EI of some human activity may apparently remain constant or increase only at a slow rate until at some point a threshold is reached and EI rapidly increases.
One example Harte considers is an effect of the combustion of fossil fuels. This causes acidification of the lower atmosphere with resultant acid rain, which harms or destroys plant and animal life in lakes. Below a certain level of acidification, the alkalinity in the water buffers the pH, but above a certain level of added acid, the buffering fails and the pH falls rapidly with disastrous consequences for wild life. Now the increased combustion of fossil fuels is of course related to the increased affluence of parts of the human population, but more particularly to the massive increase in that population.

The second reason for the non–linear relationship is the synergic effect of two different factors. “Synergy occurs when the combined effect of two causes is greater than the sum of the effects of the two causes acting in isolation of each other”.

For example, climate warming and deforestation, both related to human population growth, stress biodiversity in forested areas of the world. Harte does not give actual examples of the effect of either factor. But as regards climate warming, one example is the harmful effect of warming on boreal forests containing cold loving trees (see Earth Observatory Nasa). And one notable way deforestation stresses biodiversity arises from the fact that deforestation reduces the size of the area available to plant and animal species and since many species occupy relatively small total geographical areas, this leads to species loss in forest ecosystems.

But climate warming is also projected to cause forest dieback (effectively, deforestation) because drought conditions are predicted to become more frequent. And at the same time, deforestation releases the greenhouse gas carbon dioxide to the atmosphere, exacerbating global warming. “Thus the sum of the effects of each of these two stresses, climate warming and deforestation, generates additional stresses that reinforce the total response”.

The third reason concerns 'positive feedback'. This refers to the situation where some factor X alters some feature P in such a way that the change in P magnifies the effect of X. An often quoted example, and Hart gives it, concerns global warming. As greenhouse gases (X above) build up in the atmosphere, the Earth's surface temperature (P) rises. But one consequence of this is that the area of the Earth covered in ice or snow decreases. Since ice and snow are white, they reflect much more light than darker bare ground or ocean. So as the former decreases and the latter increases, more sunlight is absorbed at the earth's surface and there is additional warming of the Earth. Now Harte and a colleague Torn have worked out a mathematical equation that encompasses the feedback effect. This is ΔT =ΔT_O/(1—g). g is called the 'feedback factor'. Here if g is positive but less than one, the feedback result is ΔT >ΔT_O, the positive feedback situation.

Harte then asks the question, “are there feedback processes in which the feedback factor, g, grows with the size of the population?” He notes that not all feedback processes are dependent on population size. Thus with the snow/ice melt just mentioned “the direct temperature change that triggers the feedback will depend on population (because people emit greenhouse gases) but the feedback factor, g, depends only on the physical properties of ice and snow, and on the relative response of temperature to a unit change in surface reflectance; it will not depend on population size”.

However, an example where g increases with population size comes with people's reaction to climate warming: in a warmer climate, many people will respond by making more use of air–conditioning, so increasing the burning of fossil fuel, leading in turn to increased emissions of the greenhouse gas Carbon Dioxide and consequently increased global warming.

Harte goes on to point to what he considers is a more significant positive feedback to global warming that is affected by population size, one that is associated with agriculture. Carbon Dioxide is produced by the decomposition of soil organic matter. Now climate warming is likely to increase this decomposition, particularly, Harte says, in tilled, fertilized and irrigated soils. He comments:“Because the total area of such lands depends on population size, the gain factor, g, associated with this positive feedback is dependent on population size”.

Harte then goes on in his paper to consider some other relationships between population size and EI. He draws attention to the importance of what are called pollutant 'sinks'. In relation to global warming, the effect of man on the atmosphere is mitigated by the fact that roughly a third of the carbon dioxide produced by human activity and liberated into the atmosphere is removed by the oceans and forests, which then are pollutant sinks. But just like kitchen sinks, “they can partially clog if too much is put down them”. Harte concludes “thus the rate at which carbon dioxide can be removed from the atmosphere is a declining function of the amount that has already been removed, and so, in effect, is a declining function of population size at a fixed per capita affluence level and fixed technology”.

Harte notes that the ocean and forest carbon sinks can be thought of as non-renewable resources. Environmental problems become more severe when we use up these sinks. And the faster the human population grows, the quicker we use up these resources. Now natural gas is a cleaner alternative to coal, but the trouble is, we are rapidly exhausting the supply of this energy source.

The supply of clean fresh water poses a similar problem. Supplies in aquifers and rivers are of course renewable, but man has been removing water faster than it is naturally replenished; “then for substitutes we have to turn to new technologies to provide water, and many of these, such as dams and desalination, bring about environmental costs”. Global warming with more severe droughts in some major food producing areas will exacerbate the problem and the general solution will be to turn increasingly to more energy–intensive means of obtaining water to sustain a fixed level of per–capita affluence and this will accelerate global warming.

Harte concludes: “Hence we can think of the term T in IPAT, the impacts from the technologies needed to sustain a given per capita level of affluence, as inevitably a function of population, P”.

Up to this point in his paper, Harte has stuck to the environmental implications of population growth. But he then goes on briefly to comment on the social implications:
He notes that attempts to resolve social problems such as growing disparities between income, cultural and racial groups are made more difficult by rapid population growth because institutions cannot keep up with the provision of services. And there is a harmful feed back here to environmental problems. Harte takes as his example, the desirable objective of introducing a carbon tax to discourage fossil fuel consumption. In a society with only small income disparities, as a sales tax, the burden would not fall disproportionately on any group. But where there is a wide income disparity between groups the burden falls disproportionately on the poor by reason of the fact that they have to spend a larger fraction of their income on necessities like fuel than the rich. And this reduces the feasibility of introducing such a tax.

In the last section of his paper before the concluding remarks Harte looks at the implications of his analysis for dealing with global warming. He does this in relation to the concept of 'policy wedges' developed by Pacala and Socolow who illustrate their concept by a diagram. The basic idea here is that no single policy (sector or 'wedge' in the diagram) will be adequate to cope with global warming. We need a whole raft of policies (all the wedges of a possible comprehensive climate change policy) if we are to cope. Further, it will not be enough simply to aim to keep emissions at the year 2000 level: global warming would then still intensify in the future because a steady level of emissions at the year 2000 rate would lead to a continuing build up of carbon dioxide in the atmosphere. “To eventually stabilize the human contribution to climate change, we actually have to reduce emissions down to a level at which the removal of carbon dioxide from the atmosphere by natural sinks will result in a constant concentration of this greenhouse gas” (our italics).

None of the basic ideas here are new; in fact they have been asserted again and again by various experts and organisations. But the diagram helps us to visualize the situation in an effective way. And Harte adds a modification to the diagram - he introduces 'destabilizing' wedges such as feedbacks and the clogging of the carbon sinks that work against policies of rectification. These will be magnified by continued human population growth.

We end by mentioning two of the points that Harte makes in his concluding remarks.
First, he argues that the general structure of the population–EI relationship that he has expounded warrants “considerably greater concern over population growth...than has generally been shown by public policy makers”: the 'traditional' viewpoint is that population growth has a simple linear relationship with EI, whereas synergies, feedbacks and thresholds considerably magnify the effect of population growth.

Second. Present day global inequalities between peoples like the distribution of resources, will pale in comparison with the inequality in quality of life between us today and people born tomorrow if present environmental trends continue. “As the stewards of our descendents, it is our moral obligation to better understand that landscape and seek pathways to the future that avoid such rapidly escalating damages. Implementation of family planning policies throughout the world that give people greater control over reproduction, in under–developed and over–developed nations alike, is a critical step toward that end”.

Carr, D. L, Suter, L & Barbieri, A. (2005). Population dynamics and tropical deforestation: State of the debate and conceptual challenges.
Population and environment 27, 1: 89-113.

In Gaia Watch, we consider that “at the global level, human population growth is one significant cause of environmental problems - destruction of natural ecosystems, increased rate of species extinction, soil erosion, falling water tables and depletion of aquifers, pollution of rivers, seas and coastal waters, increase of harmful emissions to the atmosphere” (see our Home Page). But we have never asserted that the relationship of population growth to environmental problems is a simple one, and some of the items already on our web site indicate the relationship is complex. The paper by Carr et al. illustates the complexity of the relationship for one of the most important ecosystems, namely tropical rainforests.

This paper is the outcome of work promoted by the Population Environment Research network (PERN) including a cyberseminar, and claims to draw together the conclusions of the various strands of research that cover or impinge on the field of the relationship between human demographic variables and tropical deforestation.

It seems widely agreed that the relationship between population and deforestation in general, i.e. not just in the tropics, is complex. As two authors (Geist and Lambin) put it “demographic drivers of deforestation nearly always operate in tandem with political, economic and ecological processes at various scales” (page 91).

The spacial scale of investigations is important. For example, global or national level analyses may show a correlation between population growth and level of deforestation. Yet at the more local level there maybe, for example “the seeming paradox of rural population decline in many Latin American nations coinciding with continued high rates of forest clearing” (page 93). This particular apparent paradox is explained by the fact that while national populations are growing, and the total national demand on forest services is increasing (both for home use and for the export of tropical timber as a steady source of wealth), at the same time, in some areas, many people are migrating to the cities with the hope of employment and a higher standard of living, thus reducing rural population density.

Despite the growing size of urban populations, the impact on forest area of this growth may be less than one might expect, indeed there may be “favourable forest trends" (page 96). For example, there may be a reduced dependence on fuel wood, fuel needs being met by fossil fuels rather than wood and charcoal. Forest regrowth may take place as marginal agricultural land (originally established by cutting down forest areas) is abandoned because of a dearth of rural labour, or there may be government sponsored replanting programmes. However, while such planted forests do provide some environmental services like reducing soil erosion, they are frequently “only an impovershed replacement of the original forest” and as one commentator put it “reforestation is now as great a threat to bio-diversity as deforestation”.

Although the adverse impact of local land users on forests may sometimes wane, as mentioned above, nevertheless deforestation resulting from local users remains a common feature of many regions. For example, the demand for fuelwood for household consumption in the arid and populous regions of East Africa and South Asia “is perhaps the primary proximate driver of deforestation in these regions” (page 98).

Much discussion on environmental impact has centred on the famous Impact equation I=PAT, where I = environmental impact, P= population and T =technology (page 100). Now the authors of this paper write that in virtually all studies, “ policy and institutional factors (absent in the I=PAT formulation) were implicated as driving factors”. Further, they conclude that “economic factors appear to exert a stronger influence on deforestation than does population”. The effects of increased technological efficiency however are mixed. Use now of technology like chain saws and heavy equipment may increase the rate of deforestation.
At the same time, improved technology may reduce environmental impact. For example, agricultural intensification may be through “technological substitution to raise yields on a given area of land as opposed to raising yields by investing in more labour or by expanding cultivation to encompass a larger area” as in deforestation (page 101).

Considering policy and institutional effects, the authors note the literature shows various factors that contribute to deforestation. Thus in the Amazon, there have been official schemes of land colonisation and induced immigration, and “subsidies and tax incentives for investment in cattle ranching, which demand large extensions of land in the Amazon and triggered land speculation”. “ Institutional failure, especially due to inefficiency, mismanagement and corruption in the government sector, has also hindered the effective use of natural resources (e.g. logging in Indonesia) and induced deforestation...”. On the other hand, cooperation between local communities and international institutions, transnational corporations and NGOs have in some places enhanced resource conservation (page 103).

The authors end their paper by a section that looks at policies and possible future research that may lead to reduced adverse impact of human populations on forests. Policy suggestions range from extending family planning with the aim of achieving a “long–run balance and stabilisation between consumption and supply of naturall resources, particularly forests”, to creating new forest reserves where the focus is not just on forest cover but rather on the preservation of areas of high biodiversity.

For another analysis of the impact of human population growth on deforestation see our review of J. K. McKee's book “Sparing nature” on our Book Reviews page.

Report of Hearings by the All Party Parliamentary Group on Population, Development and Reproductive Health (January 2007). Return of the Population Growth Factor. Its impact upon the Millennium Development Goals. House of Commons.

This report is an exploration of how to reach the 'Millennium Development Goals' that were set by the United Nations. These goals concern ways to transform poverty stricken countries, largely countries with agricultural–based economies in the 'third' or non–industrialized world, into countries with modern, healthy economies.

The first four paragraphs of the report's Foreword succinctly both identify the problem and indicate the solution:
“In 2000, 189 governments committed themselves to achieving the Millennium Development Goals (MDGs) by 2015. At current rates of progress however, we will not meet these Goals unless governments and their partners turn words and promises into resources and action”.
“A lack of access to Sexual and Reproductive Health (SRH) information and services leading to high fertility and subsequent population growth, particularly in the poorest countries, continues to pose significant challenges to development and the attainment of the MDGs. And high levels of fertility and population growth make it far more difficult for families and societies to overcome poverty”.
“The pace of growth of the world's population increased markedly throughout the last century and we can anticipate a further 50% increase in the world's population by 2050. Many experts agree that world population growth poses serious threats to human health, socioeconomic development, and the environment”.
“Population issues have lost priority, compared to other concerns of civil society and economic development. Funding has stagnated or decreased at a time when unmet need for family planning information and services is increasing” (our italics).

So population growth and government failure to adequately fund sexual and reproductive health information and services programmes are the causes of failure to meet the Millennium Development Goals. But why have Population issues lost priority? The report traces the beginning of this loss back to the 1994 United Nations conference in Cairo. This conference focused on the reproductive rights of individual women, improved education and healthcare services. It deliberately turned away from the issue of population growth because this topic had become inextricably associated with coercive population policies and coercion was condemned. The authors of the present report however, consider that something can be done to slow population growth without any coercion.

The report spells out the harmful effects of population growth:

• Most of current population growth is taking place in the world's poorest countries (page 18). The rapid pace of this growth means that “we are not even succeeding in keeping the numbers living in extreme poverty stable” (page 20). In fact the number of people living in extreme poverty has grown from 231 million in 1990 to 318 million in 2001 (page 20), countervailling the positive effects of economic growth (page 22).
• Rapid population growth and so increase in population density in rural areas leads to within–country migration to urban areas and the growth of densely populated slums; in fact urban slums will absorb most of future population growth (page 25). Overcrowding creates the conditions most favourable to the spread of diseases including HIV (page 43).
• Population growth has outstripped the ability of governments to provide services, for example health services (pages 36 and 44), and education so that “universal primary education becomes an illusion” (page 29).
  This shortage of services is partly caused by a shortage of professional workers and this is exacerbated by the emigration of such workers from areas of low opportunity and deteriorating economic circumstances including decreasing educational and job opportunities, to developed countries (pages 25 and 44).
• Rapid population growth is often one cause of civil conflict (pages 24 and 56, and in relation to shrinking water supplies page 53). And the report notes that “countries in which young adults comprise more than 40% of the adult population, are more than twice as likely as countries with lower proportions, to experience an outbreak of civil conflict” (page 24); this applies to some of the poorest countries. Women in situations of conflict and migration are more vulnerable to sexual violence, and maternal mortality rates may be increased (page 42). Conflict exacerbates poverty (page 22).
• Underlying all these effects of population growth are the consequences of this growth for the very environment that sustains all human populations — “ environmental degradation is commonplace in many parts of the world, as increased numbers of people struggle to feed themselves” (page 48).

The report details this environmental deterioration:

• Extensive deforestation to obtain wood for fuel and construction and land for growing crops exacerbates climate change which in turn has harmful effects on the environment (page 48). Soil exhaustion occurs from attempting to increase food yields in existing agricultural land and extending cultivation onto unsuitable land like hill slopes, to feed the growing population. This with overgrazing leads to soil erosion and so further environmental deterioration (page 27) (see our 'Royal Society Warning to the G8 on Climate Change, but there is another warning that should also be given' in the Comment section of our Comment and Analysis page).
• Coastal and marine ecosystems are also “facing increasing pressure. Forty percent of Africans already rely upon coastal and marine ecosystems, but if current patterns of migration continue, this figure is set to continue increasing, further degrading resources and leaving whole communities vulnerable to disaster” (page 48). Ocean fisheries are being over–fished (page 49).
• A vital part of the environment for man is its supplies of fresh water. And the report notes: “Consumption of fresh water for agriculture, industrial and domestic uses increased six–fold in the 20th century” (page 51). Part of this increase has of course been caused by increased per capita consumption in industrialized countries, but rapid global population growth is a major causal factor. “Ground water supplies are falling in large parts of Asia, with little indication they could easily be replenished while population grows... groundwater supplies are facing serious depletion and contamination from intensive agriculture” and so on (page 52).

In view of all these facts about the environment, it is not surprising that the report is cautious about the ability of the planet to sustain adequate food production. The report notes that global food production has kept pace with population growth during the second half of the twentieth century, but there is no guarantee that this production will keep pace with future population growth, indeed “the rate of increase in food production worldwide appears to be slowing down” (pages 26 and 27).

At the centre of the population problem is the fact that while fertility has generally been declining in developing countries, there has been a considerable variation in the time of onset, rate, and extent of this fertility decline. And the decline has stalled in some countries. Figure 8 of the report (page 19) shows clearly where this problem is greatest. Country fertility rates (births per woman) are shown here by colour, ranging from dark green (less than 1.5, through pale green, pale yellow (2.5-3.5), orange, to red (4.5. or more). What stands out is that most countries in Africa south of the Sahara, i.e. Black Africa, are red.

The report also draws attention to Egypt. Here fertility decline has stalled at 3.5 children and the population is projected to nearly double by 2050. Now the water in the Nile river is severely depleted by the time it reaches the Mediterranean region and there is a real possibility that the amount of water available to Egypt may decline in coming years; meanwhile the demand for water in Egypt continues to increase.

And the report notes that “with the exception of a few oilrich states, no country has risen from poverty while still maintaining high average fertility. Conversely, many countries that lowered their birth rates, such as South Korea, have eradicated or greatly reduced poverty. Continued rapid population growth in today's poorest countries presents a serious barrier to meeting the MDG of poverty reduction”.

What then needs to be done to enable the Millennium Development Goals to be reached?

Globally, the report sees the solution first and foremost as reducing population growth by making contraception devices, health care services and education more widely available. It claims that most people in developing countries would reduce their family sizes if they were given the means to attain this goal (“125 to 200 million people would like to be able to control their fertility, but are not using contraception” (page 14). The report cites as evidence that in most sub-Saharan countries the fertility of the richest 20% of people declined by more than 1.5 in the last decade, but the fertility of the poorest 20% either remained unchanged or increased by more than one child. This suggests, the report argues, that “the high fertility of the poor may be largely unplanned or unwanted” (page 15).

The authors of the report tackle the question of coercion that so bedevilled the Cairo conference, and make it clear they wish to avoid such coercion. We read about the “human right of couples to make voluntary decisions on when to have a child” (page 9, our italics). They quote S. Sinding “I think the taboo (about population at the Cairo conference) was the result of a mythology that equated population policies with coercion. I think this was a misrepresentation of the reality of population policies and population programmes around the world, not withstanding the fact that the two largest countries, India and China, were both guilty of coercion in their programmes” (page 11).

Yet the report admits that “The People's Republic of China, through a combination of lowered birth rates and economic reform, has lifted 150 million people out of abject poverty and are meeting the MDG for poverty reduction a decade earlier than the target date of 2015” (page 21). What the report does not explore is — what would have happened to China's population if the coercive one child policy had not been adopted? The population growth would in our opinion have rocketed, making it impossible to achieve the economic growth that has been achieved, and environmental degradation would have been far more severe than it actually has been.

Perhaps coercion is not such a bad thing after all. Which is better — to insist on individual human rights and avoid any coercive measures, resulting in further descent into poverty, increased conflict, breakdown of social order, and massive increase in mortality, or alternatively, put the good of the whole population above the rights of individuals, and thus secure a reduction of population growth with all its concomitant benefits?

Furthermore, the report sees just two situations, individual rights supreme with no coercion, and coercion. But this leaves out a middle way of 'sticks and carrots', aimed at persuading without threatening, people to limit their reproduction. After all, in east Asia — so lauded for its economic success — some governments adopted incentives and disincentives to encourage small rather than large families. As Mason noted “Singapore adopted a comprehensive set of incentives and disincentives..., and similar efforts were pursued elsewhere in the region” (Mason, A. (2003). Population change and economic development: what have we learned from the East Asia experience?. Applied population and policy 1, 1: 3–14. See page 11).

As we have already noted, the report does acknowledge the relationship between population growth and increase in conflict. And it mentions, almost in passing, 'poor government' (in Nigeria — page 22). But it does not draw attention to the massive corruption amongst leaders and governing elites in some Black African countries that has characterised the last half century. It does not mention the scant regard for human rights shown by many African countries, exemplified now with the conference of southern African leaders — just coming to an end as this paragraph was being drafted — where Mugabe's atrocious record on human rights seems to have been ignored! (link)

This 'poor governance' is, in our view, an underlying cause of the problems of Black Africa. And we note that Asian countries generally, during the last half century, experienced more political stability than in most of Latin America and sub-Saharan Africa. Consequently, their governments could realistically pursue long-term goals (Mason, ibid. See our essay 'The demographic dividend' accessed from the Analysis section of our Comment and Analysis page).

One thing that positively hits one in the eye as one reads through this publication, is the extent that Africa stands out. We have already referred to the map of the world showing fertility rates (figure 8). But in the map showing low primary school completion rates (figure 11 page 31), 'middle Africa' also stands out, as it does also in the map of worldwide maternal mortality (figure 16 page 40). And there are numerous references to the serious situation in African countries in the text. We cannot help asking - “why Africa?” Is Africa the only region of the world to suffer from exploitation by First or Industrialised countries (a beloved topic of the politically correct)? But the authors of this report don't ask that question, and in our view, that is a question that needs asking by any persons who want to rectify the global situation.

We think that without facing up more squarely to the issue of 'poor governance' in many poor countries, it will not be possible to work out a strategy that has a reasonable chance of achieving the Millennium Development Goals. Even if poor governance was properly taken into account, the dire situation, economically and politically, in many of these countries, viewed against the background of the severe environmental degradation that has already taken place, the likely future conflict over water resources and the likely adverse future environmental changes caused by global warming, it is unlikely, in our view, that the MDGs will ever be reached.

This well produced document provides concise summaries in numbers and graphics of population and other MGD matters.

Dietz, T., Rosa, E. A. & York, R. (2007). Driving the human ecological footprint.
Frontiers in Ecology and the Environment 5, 1: 13-18.

This important paper makes an analysis of 'anthropogenic' (stemming from human activity) environmental degradation, with the purpose of identifying the 'primary drivers' of this degradation. And the authors state at the beginning that there is growing evidence supporting the hypothesis that population and affluence are the primary drivers.

However, does increasing affluence invariably lead to increasing adverse environmental impact? And how significant are other postulated drivers, other 'anthropogenic stressors' for example, age structure: persons under the age of 15 consume less and are less involved with production activities than adults, so we might expect greater environmental impacts from populations with a higher proportion of adults than populations with a younger age structure.

To answer these questions the authors make use of a model derived from the famous impact identity I=PAT: impact = population × affluence × technology (see the essay “I=PAT. An Introduction” accessed from the Analysis section of our Comment and Analysis page). This is the 'STIRPAT MODEL' (“stochastic impacts by regression on population, affluence and technology”), a model developed earlier by Dietz and Rosa. The measure of anthropogenic stressors they use is the ecological footprint and a brief overview of the footprint method is given in the paper. But briefly, the method involves converting all forms of consumption into land areas, for example crop land, or forest land for absorbing carbon dioxide emissions from energy production, at current consumption levels. And the 'global footprint' is the footprint of all humanity. The method is described in more detail in our essay “How many people can the earth support? (part 2 - Ecological Footprints)”, accessed from the Comment and Analysis page of our web site, Analysis section).

What were the results? As might be expected, population comes out as a very significant driver. “...a 1% change in population induces a nearly equal percentage change in impacts”.

What about affluence? Now in the early part of their paper, the authors note that evidence had previously been found that with some particular impact agents, notably some air and water pollutants, during economic growth, environmental impact initially increases, but later decreases. Economic growth was here usually represented by some indicator of increased affluence, normally increase of GDP per capita. So the relationship found was that the (per capita) impact of the population initially increases as GDP per capita increases, then steadies and later decreases. This is known as the Environmental Kuznets Curve relationship which is examined in detail in the essay “Is Economic Growth good for the Environment? An approach to this question using the Environmental Kuznets Curve Hypothesis” also accessed from the Analysis section of the Comment and Analysis page of our web site. The main point is, however, that this relationship suggests that economic growth is good for the environment.

In their investigation, Dietz et al found that not only are higher levels of affluence (GDP per capita) not correlated with reduced impact (smaller footprints) rather “higher levels of affluence produce larger footprints than would be expected from a strictly proportional relationship”.

Three other postulated drivers, namely age distribution, urbanization and economic structure (the extent that economic activity is in the environmentally relatively benign service sector) were not significant drivers.

Two other factors were significant. First, the more land per capita, the greater the impact. This suggests to the authors that “patterns of more wasteful resource use have emerged in large nations”. Second, the impact of countries in temperate and arctic latitudes tends to be greater than the impact of countries in the tropics, suggesting that cold climates lead to increased energy consumption that in turn increases the ecological footprint.

Further analysis broadened the investigation to look at indicators of human well being, making use of United Nations indices for educational achievement and life expectancy. The authors found that if one controls for other variables, neither indicator was related to environmental impact, suggesting that “while increasing affluence does drive impacts, it is possible to improve other aspects of human well-being without adverse environmental effects”.

The authors went on to make a projection of the global footprint in 2015, making use of United Nations medium population projections and assuming moderate economic growth. The 2001 footprint of 13.5 billion hectares is projected to rise by 34% to 18.1 billion hectares. Ecological footprints are often compared with the total size of productive hectares on earth. Such comparisons make current human demand equivalent to 1.2 planets, so we are already, at current consumption levels, overshooting the long-term capacity of the earth to sustain the human population. By 2015, the figure is projected to rise to 1.6 planets. The countries with the greatest absolute increase in footprint will be China and India. This is no surprise: these are the two countries with the largest populations, and there is continuing massive population growth and rapidly increasing economic growth.

What conclusions do the authors reach about human prospects? They discuss this in terms of improving technology, noting that it has frequently been suggested technological progress can redress environmental problems. They say technological improvements would need to exceed 2 % per year. They argue that this is feasible, since at least as far as energy efficiency is concerned, some nations have improved this efficiency by as much as 5 % per year. However, “...this goal may be technologically feasible, although difficult in the face of economic and institutional obstacles....We also do not know whether the production efficiencies of non-energy resources can be improved so rapidly”. And the authors warn against “complacency about global environmental impacts”.

What should we make of this point of view? “Economic and institutional obstacles”. The authors do not elaborate, although they say elsewhere in their paper that the evolving environmental policies of India and China “will undoubtedly be critical in the move towards global sustainability”. We imagine these obstacles may be both numerous and serious. Think only of power supply. A BBC report 14th February 2007 (“coal blackens outlook in China”), paints a sombre picture. Shanxi province is said to be the worst province for pollution. “When you are driving you often can't see clearly in front of you. A lot of accidents happen because people can't see”. And according to this BBC report China is expected to go on opening new coal fired power stations at the rate of about one a week for years to come”!

We also note that this article by Dietz et al says nothing at all about the possibility of doing something about human population growth, growth that even from their analysis alone, is a highly significant cause of increasing global environmental degradation. In this, the authors fall in line with the majority of environmentalists and economists, who put their faith in decreasing per capita consumption in the industrialised world and improving technology, the 'A' and 'T' of the Impact equation I=P×A×T. But we argue intervention is also needed with 'P'. So in the terms the authors themselves use and narrowing our focus on India and China, rather than saying the evolving economic policies of these nations will be critical, we say population policies will also be critical.

Coleman, D. (2006). Immigration and Ethnic Change in Low-Fertility Countries: A Third Demographic Transition.
Population and Development Review 32, 3: 401-446.

David Coleman is Professor of Demography at Oxford University, with over 90 papers and eight books to his credit, so when he writes about a demographic matter of considerable public concern, we should consider carefully what he has to say.

He frames his analysis in terms of past changes in fertility, mortality and behaviour in industrial societies, as they have gone through what are termed the first and second demographic transitions. These are described at the beginning of our Population Trends page so there is no need to rehearse their features here. David Coleman thinks that some of these countries are now experiencing a set of population processes that amount to a Third Demographic Transition. The key features of the situation are first, persistent low fertility and second, high immigration.

European countries have been experiencing below replacement level fertility rates – for several decades in Western Europe, for a shorter time in Southern and Eastern Europe. At the same time, Western European countries and the United States have in recent times been experiencing high levels of net immigration, where immigration streams have included significant numbers of “persons from remote geographic origins or with distinctive ethnic and racial ancestry” (parts of Eastern Europe have had only modest migration flows).

Consequently the compositions of country populations are changing, with an increase in the proportion of persons of foreign descent and non-native ethnic groups: “The processes...resulting from low fertility combined with high immigration, are significant because they are changing the composition of national populations and thereby the culture, physical appearance, social experiences, and self-perceived identity of the inhabitants of European nations”. If these processes persist, resulting in permanent changes, we may, Coleman says, regard the whole transformation as a Third Demographic Transition.

What of long term consequences if these processes continue? According to theory, any population with below replacement level fertility where, through net immigration, the size of the population is either maintained at a constant level or increases, will eventually be transformed until that population is predominantly and eventually entirely of immigrant origin. The original population has been displaced. Furthermore, even if the fertility of immigrant populations, initially high, falls to the level of the host population, this will not ultimately prevent this replacement.

In practical terms, future changes are investigated by making projections, and Coleman discusses projections that have been made for Western European countries, after providing for Europe (and the United States) details of fertility and immigration and the growth of foreign-origin populations in the past. For such projections, investigators in different countries have classified their populations in different ways, depending on availability of data. The Austrian projections, for example, only have people classified as 'citizens' and 'foreigners'. In contrast, with projections for Germany, the population is divided into five categories: Germans, Turks, Yugoslavs, Other European Union, and Other Foreign.

The projections are based on assumptions made about fertility, mortality and migration. Coleman makes the generalisation that projections assume the fertility of populations of Western origin will converge to the native average, the fertility of non-European populations to around replacement level or slightly above it. With mortality, existing foreign-origin populations have mortality rate similar to the national-origin populations, and apart from Sweden, all the projections assume death rates to be similar across the board.

Migration assumptions “are the most troublesome of the three. Statistics on current levels of migration are unsatisfactory”. But Coleman gives compelling reasons for supposing levels of migration will continue at their present levels, or more likely increase, in the foreseeable future: Gross and net immigration, despite fluctuations, have been growing in recent decades. And underlying these trends are the twenty-fold differentials in per capita earnings and large differences in population growth rates between countries of origin and Western European countries. Further, economic disparities have widened in African and other countries that also have the highest levels of population growth. Not surprisingly then, most of the projections that Coleman details assume much of future immigration will come from what he describes as 'non-traditional' sources.

Coleman also notes that future immigration from poor countries is supported by chain migration (migration such as that for arranged marriages facilitated by earlier migrants who have established communities in the host countries), and by the rights of immigrants currently accepted by host countries, notably post–World War Two human rights conventions. Immigration is also facilitated by “the transformation of the host societies' institutions, culture, language, and politics into forms more conducive to continued migration, so that in some respects they come to resemble more closely those of the sending countries”.

A summary of population projection assumptions and results for Western European countries where researchers have in some way separately recorded foreign-origin populations in their analyses, are given in table 1 of Coleman's paper. Further details are given in the appendices. These countries are Austria, England and Wales, Denmark, Germany, Netherlands, Norway and Sweden. Between 2000/2001 and 2050/2051, in all these countries, there is projected to be a large increase in the percentage of the population that is 'foreign' (variously defined), ranging from 6 to 25 per cent. For example, with Germany, the percentage foreign (sum of the four foreign groups mentioned earlier) rises from 9.9 in 2000 to 23.6 in 2050. With England and Wales the non-white ethnic minority populations increase from 8.7 to 24.5 per cent in 2051, and the white non-British-origin populations from 2.7 to 11.6 per cent. So the total 'foreign' population rises to a massive 36.1 per cent. We note that the conclusions for England and Wales receive support, for the period 2001 to 2020, by the research of P. Rees (see Salt and Rees 2006, “Globalisation, population mobility and impact of migration on population”, The Economic and Social Research Council).

The changes in population composition will not cease in 2050, so in the long term, there is likely to be a massive transformation of the ethnic or racial composition of Europe. Is there any precedent for such change? Coleman notes that change in population composition through migration has been a feature throughout Europe's history. Major movements of population started BC and continued in the early centuries AD. Coleman thinks the Anglo-Saxon invasions may have contributed up to 20 per cent of English ancestry, the later Danish invasions 2-4 per cent, the Norman 'kleptocracy' not more than 1-2 per cent, but, he notes, all these changes were over a protracted period of time. “...it is certain that nothing remotely like these events has happened since in the British Isles. The effect of migration into England from the eleventh to the twentieth centuries has been undetectable using genetic markers, as would be expected from Britain's political and demographic history...” .

Coleman poses the question: “Should the transformation of the ethnic or racial composition of European countries in the twenty-first century, which is presaged in these projections, be regarded as a third demographic transition in progress?”. He notes that to merit the term demographic transition, the changes must be “fast in historical terms, without precedent, irreversible, and above all of substantial social, cultural, and political significance”.

Coleman thinks the answer is yes: If the projected future changes do take place, the effects on ancestry in the long run may be greater than anything that has occurred previously, in the degree of replacement, in the geographic remoteness of sources of immigrants and in the speed of change, and the changes are likely to be permanent. They will too have profound social, cultural and political consequences (see below). So the term demographic transition will be warranted, a transition now well underway.

There are many uncertainties about the composition of future populations. For example, the projections just discussed assume that population groups remain distinct. This may not turn out to be the case. In the past, many substantial migratory groups such as the Huguenots in seventeenth-century England have become completely absorbed. And at present, the boundaries of some populations such as West Indians in Britain are becoming blurred. On the other hand, future populations are likely to include many people who self-identify as of 'mixed' origin. None of the projections mentioned include mixed categories. They all assume that children of mixed unions will become absorbed into one of the parental groups. But individuals may prefer to explicitly identify with a new identity of mixed origin, which seems to be happening in the US, and over half a million persons in Britain identified themselves as mixed or were so identified by their parents at the 2001 census. At present, some immigrant groups remain as Coleman puts it 'encapsulated', like Muslims in Britain and Turks in Belgium. And we note that this encapsulation is reinforced by a high degree of endogamy in some groups (Penn and Lambert, 2002, Population Trends 108). Later generations may not become more assimilated than the first, or become even more alienated, which seems already to be the case with some groups, for example young North Africans in France.

Despite such uncertainties, it seems clear that the demographic changes taking place have serious consequences for the cohesion and values of future societies. As Coleman puts it “when democratic societies acquire multiple cultures, new wedges may be driven into the social structure”. Perceptions of identity, in the past focused on the nation state, are changing. The current emphasis, for example with welfare concerns, is not on a “universal secular citizenship in a broader society” but on kin, community and religion.

In this situation, native populations have been put at a disadvantage. Thus concerns for human rights focus almost entirely on the rights of immigrant populations, not on the rights of native peoples to conserve there own way of life, with their own language, laws and communities. “Principles of cultural conservation, nowadays recognized and defended on behalf of the Yanomamö and Tapirapé of the Amazon forest..., find little parallel on behalf the native inhabitants of Tower Hamlets or Toulouse, although their complaints would meet most of the criteria proposed for such protection...In Europe, local nativist protests tend to be denounced as racist, xenophobic, and deluded...”.

With larger numbers, foreign origin populations may feel less need to adapt to local norms, rather they may become more confident in attempting to extend their own values, language and laws in the wider society. Already in Britain, Muslim organisations, noting the increased numbers of Muslims shown by recent censuses, have been pressing for the introduction of shari'a law in parts of Britain where Muslims already predominate. This ties in with what we have written elsewhere on our web site, especially in the essay “The Muhammad cartoons controversy - the context”. We note there some Muslim leaders who seek to transform Britain and indeed the whole of Europe into part of a world wide Islamic state. We believe that a far greater proportion of the present Muslim population of Europe have this aim than is currently acknowledged by officialdom.

Coleman ends his paper by noting that the changes in European populations described are proceeding despite widespread opposition from the public to the levels of migration that are causing them. “In ignoring the long-term consequences the countries of the West are facilitating a radical transformation of the composition of their societies and the cessation of a specific heritage... democratic approval might have been thought necessary for so notable and permanent a change...” (our bold text).

Imagine earth without people.

In the New Scientist magazine, issue 2573, 12th October 2006, an intriguing article appeared: “Imagine Earth without people”.

The article examines what the effect would be on the world's environment, ecosystems and biodiversity, if the entire human population of the world (6.5 billion people) was spirited away from the planet.

The opening paragraph is important in its own right, as it succinctly summarises mankind's impact on the planet:
“Humans are undoubtedly the most dominant species the Earth has ever known. In just a few thousand years we have swallowed up more than a third of the planet's land for our cities, farmland and pastures. By some estimates, we now commandeer 40 percent of all its productivity. And we're leaving quite a mess behind: ploughed-up prairies, razed forests, drained aquifers, nuclear waste, chemical pollution, invasive species, mass extinctions and now the looming spectre of climate change. If they could, the other species we share Earth with would surely vote us off the planet”.
Here we see just what human population growth has done to our wonderful planet, what it has done to the whole Gaian system (see our reviews of books by Lovelock, Diamond and McKee, and of the Millennium Ecosystem Assessment).

The article tells us that if the human population was suddenly removed and the planet was viewed from orbit, some change would be almost immediately apparent: The blaze of artificial light that brightens the night sky, causing 85 per cent of the night sky over the European Union to be light-polluted, would quickly begin to disappear, through lack of supply of fuel to power stations.

More gradually, the other signs of man's activity would disappear and nature would re-assert itself. The best illustration of this, we are told, is the city of Pripyat near Chernobyl in Ukraine, which was abandoned after the nuclear disaster 20 years ago and remains deserted to this day. The buildings are slowly decaying. Plant root systems penetrate into the buildings, initiating the collapse of man made structures. More generally in the world, with no one to make repairs, buildings will crumble. But as archaeology shows us, we can expect signs of man–made structures to persist for thousands of years.

Most ecosystems may be expected to recover once people disappear, although recovery rates will vary. “Warmer, moister regions, where ecosystem processes tend to run more quickly in any case, will bounce back more quickly than cooler, more arid ones. Not surprisingly, areas still rich in native species will recover faster than more severely altered systems”. “In contrast, places where native forests have been replaced by plantations of a single tree species may take several generations of trees - several centuries - to work their way back to a natural state. The vast expanses of rice, wheat and maize that cover the world's grain belts may also take quite some time to revert to mostly native species”.

In the oceans, fish populations would gradually recover from over–fishing. And lakes and rivers will gradually recover from the excess of nitrate and phosphate pollutants. In the atmosphere, most of the man generated greenhouse gas carbon dioxide will disappear.

However, the recovery of ecosystems and the return to the state they were in before the advent of man will be incomplete, for various reasons. For example, the activities of man have in some areas produced new 'stable states' the properties of which will resist the return. Thus in Hawaii, introduced species of grass cause frequent wildfires and such fires in the future would prevent native forest regeneration.

Then again, some plants and animal species and strains introduced by man into ecosystems may remain as permanent members of those ecosystems, even if they undergo further evolution in the course of time – horses, cattle, pigs, wheat strains. Genetically modified (GM) crops are less likely to survive. For example, “GM bent grass is engineered to be resistant to a pesticide, which comes at a metabolic cost to the organism, so in the absence of spraying it will be at a disadvantage and will probably die out too”.

Furthermore, the removal of man would not restore all the species that have already become extinct. And it would not save all those species that are presently close to extinction: Some species have probably already past some “critical threshold below which they lack the genetic diversity or the ecological critical mass they need to recover”. Invasive introduced predatory or competitive species may also cause further species extinction.

Even where one might expect fairly rapid recovery of ecosystems, that recovery may in fact be delayed. Consider for example, ocean stocks of fish like cod, which have slumped. “The problem is that there are now so few cod and other large predatory fish that they can no longer keep populations of smaller fish such as gurnards in check. Instead, the smaller fish turn the tables and out–compete or eat tiny juvenile cod, thus keeping their erstwhile predators in check. The problem will only get worse in the first few years after fishing ceases, as populations of smaller, faster-breeding fish flourish like weeds in an abandoned field. Eventually, though, in the absence of fishing, enough large predators will reach maturity to restore the normal balance. Such a transition might take anywhere from a few years to a few decades”.

Amelioration of climate change effects will not be a simple matter, despite loss of most of the man-made carbon dioxide in a few decades, so global warming – with all its adverse effects on ecosystems – will continue for another century. About 15 per cent of the CO₂ from burning fossil fuels will remain in the atmosphere, leaving its concentration at about 300 parts per million compared with pre-industrial levels of 280 ppm. “There will be CO₂ left in the atmosphere, continuing to influence the climate, more than 1000 years after humans stop emitting it”.

There is uncertainty too about another important greenhouse gas that produces about 20% of current global warming, namely methane. The chemical lifetime of methane in the atmosphere is only about 10 years, so its concentration could rapidly fall to pre-industrial levels if emissions were to cease. “The wild card, though, is that there are massive reserves of methane in the form of methane hydrates on the sea floor and frozen into permafrost. Further temperature rises may destabilise these reserves and dump much of the methane into the atmosphere”. “We may stop emitting methane ourselves, but we may already have triggered climate change to the point where methane may be released through other processes that we have no control over”.

However, eventually, after at most “a few tens of thousands of years”, almost every trace of mankind's dominance on the planet will have vanished. And “alien visitors coming to Earth 100,000 years hence will find no obvious signs that an advanced civilisation ever lived here”.

The New Scientist article may be accessed by the following link:
http://www.newscientist.com/channel/life/mg19225731.100

The Tragedy of the Commons - and Human Population Growth.

A very important paper which dealt with the relationship of human population growth to mankind's impact on the environment appeared in 1968: Hardin, G. The tragedy of the commons. Science 162: 1243-1248. Now a new paper provides an assessment of how this commons idea has fared since Hardin wrote his paper: Soroos, M. S. (2005). Garrett Hardin and tragedies of global commons. Chapter 3 in P. Dauvergne (Ed.) Handbook of global environmental politics. Edward Elgar. We deal here with these two papers, starting with Hardin's.

Hardin asks us to consider a pasture, shared by all the local herdsmen. He writes that it is expected that each herdsman will attempt to keep as many cattle as possible on the commons. For a long time this arrangement may work alright because the numbers of both people and cattle are kept below the carrying capacity of the land by poaching, tribal wars and disease. However, in the end, the land does become so seriously overgrazed that all the herdsmen begin to see “the remorseless working of things”.

Expanding on this line of thought Hardin argues as follows.

Each herdsman, will seek to maximise his gain. “Explicitly or implicitly, more or less consciously, he asks, 'What is the utility to me of adding one more animal to my herd?' This utility has one negative and one positive component”.
The positive component is a function of the increment of one animal. All proceeds from the sale of an additional animal go to the herdsman, so “the positive utility is nearly 1”.
“The negative component is a function of the additional overgrazing created by one more animal”. But the effects of overgrazing are shared by all the herdsmen. Therefore “the negative utility for any particular decision-making herdsman is only a fraction of -1”.

“Adding together the component partial utilities, the rational herdsman concludes that the only sensible course for him to pursue is to add another animal to his herd. And another; and another...”. But, Hardin goes on, all the other herdsmen reason in the same way, each one feels compelled to increase his herd without limit, and all this in a world that is limited. “Therein is the tragedy”. So “ Freedom in a commons brings ruin to all”.

The tragedy of the commons is not confined to taking things out of the commons; it applies also to putting things in, that is pollution. The calculations of utility here are similar to those mentioned above. "The rational man finds that his share of the cost of the wastes he discharges into the commons is less than the cost of purifying his wastes before releasing them". But this is true for everybody. So the commons is increasingly degraded.

Hardin gives interesting examples of changes in the world consistent with this idea of the tragedy of the commons, one of which is the development of maritime fisheries. “Maritime nations still respond automatically to the shibboleth of the 'freedom of the seas'. Professing to believe in the 'inexhaustible resources of the oceans', they bring species after species of fish and whales closer to extinction”.

The author goes on to discuss ways to avoid the tragedy of the commons. He concludes that this will require coercive laws, but the coercion should be “mutual coercion”, that is agreed by the majority of people. That does not mean we are required to enjoy the coercion. After all, we don't enjoy current taxes, but we accept that voluntary taxes would favour conscienceless people, so we need compulsory taxes.

Hardin argues that, most importantly, we need coercion over procreation - We must abandon the freedom of unlimited reproduction: “The most important aspect of necessity that we must now recognise, is the necessity of abandoning the commons in breeding. No technical solution can rescue us from the misery of overpopulation. Freedom to breed will bring ruin to all”. Further "to couple the concept of freedom to breed with equal right to the commons is to lock the world into a tragic course of action”. And “unfortunately this is just the course of action that is being pursued by the United Nations”. For, he notes the Universal Declaration of Human Rights makes the family the natural and fundamental unit of society. From this it follows that family size decisions “must irrevocably rest with the family itself, and cannot be made by anyone else”. It is painful but necessary, Hardin writes, to deny the validity of this right. And “if we love the truth we must openly deny the validity of the Universal Declaration of Human Rights, even though it is promoted by the United Nations”.

Actually Hardin frames the argument of his paper in terms of the concepts of individual human freedoms, and the optimum population. The chapter on human freedoms and education in the book “England in the New Millennium. Are we prepared to save our countryside?” Barker, 2000 (book details on the 'Our Publications' page), gives details as follows:

“G.Hardin ...discusses the whole question of human freedom in relation to sustainable development, with special reference to the population problem (although he did not use the term 'sustainable development'). He starts from the situation at the time of early man when all people regarded the whole world as 'common' for all functions (common in the sense for example, of common grazing rights on commons in England). The history of man has partly been the history of the restriction of rights over this commons. For example, early man could deposit his waste products anywhere. Later it became necessary to develop sewage systems which limited disposal to specific sites. Morality, a codification of good conduct, changes over time. He referred here to a paper by J. Fletcher who argued that the morality of an act is a function of the state of a system at the time it is performed. However, morality is conservative, and Hardin goes on to assert that the laws of society really follow ancient ethics that are often poorly suited to the governing of the modern world.

“Every restriction on commons rights ('enclosure of the commons') involves the infringement of somebody's personal liberty. But infringements made in the distant past are accepted today almost without comment. The underlying problem is that if we continue to insist on all present-day freedoms we will bring universal ruin. Hardin develops his argument in relation to the growth of the human population, in a way that is very relevant to the sustainable development concept. The world has finite space, consequently population growth must eventually equal zero. When that happens, has the population reached its optimum for mankind, in the sense of 'the greatest good for the greatest number'? Hardin answers -no. He adduces two arguments.

“First, a theoretical point. We are concerned with two variables - population size and human good. We are enquiring if it is possible to maximise the latter when the former is maximised (i.e. at the size where population growth is forced to be zero by the finite state of the earth). Hardin asserts that it has been demonstrated mathematically that it is not possible to maximise for two (or more) variables at the same time. Second, an argument rooted in biological facts. To live, an organism must have a source of energy. This is needed for two purposes. The first is maintenance of the organism, energy to merely stay alive - 'maintenance calories'. The second (which he terms 'work') is for work in common speech, together with all forms of enjoyment, from swimming to automobile racing, to writing poetry or playing music - 'work calories'. To maximise population size we must ensure that work calories per person approach as close to zero as possible. We can attain the maximum population but only at the cost of severe restrictions.

“Hardin concludes that the optimum population, from the point of view of human good, is less than the maximum sized population. To maintain the common good into the future requires a deliberate limitation of population size. This in turn requires coercive action, which overrides personal liberty”.
Hardin's paper may be read on the internet courtesy of “Die Off” .

Soroos in his paper discusses the nature and extent of global commons, and ways to avoid the tragedy of the commons. He begins with a brief review of “Hardin's theory”. Here he considers two of Hardin's papers -the 1968 one discussed above and a later (1974) paper. But his review of the 1968 paper gives a distorted and partial account of what Hardin wrote. Soroos ignores the concept of an optimum population, and does not even mention Hardin's main conclusion, namely that avoiding the tragedy of the commons requires abandonment of the idea of freedom of unlimited reproduction, the abandonment of the commons in breeding.

In the rest of his paper, Soroos agrees with Hardin that the concept of the tragedy of the commons is applicable to some impacts of man on the environment, and like Hardin mentions overharvesting of marine fisheries as one example. But he writes that not all environmental problems conform to the concept - not all global commons are treated as being unowned. He notes for example that the oceans may be commons, but the seabed has a different legal status from the oceans above it; and the status of the continent of Antactica remains ambiguous in terms of ownership and jurisdiction.

Soroos notes that the atmosphere is a resource domain commonly referred to as a global commons, and he agrees: Most of the gases of the atmosphere are found in the lower troposphere region of the atmosphere. Here they circulate, flowing through national air spaces just as some rivers flow through national territories. But it is not possible for nations to take possession of the gases in their air spaces, so the atmosphere can indeed be regarded as “a commons that is beyond the jurisdiction of nations”. Soroos concludes that Hardin's model of the tragedy of the commons does apply to this commons.

There are, according to Soroos, five basic approaches to avert overuse or misuse of a commons:
1). Voluntary restraint.
2). Restrictions or rules placed on the use of the commons.
3). Market incentives such as taxes and fines.
4). Division of some domains into sections assigned to individual countries for their exclusive use.
5).Socialization of the commons with use limited to a community enterprise that would distribute the resulting income to the members of the community.

But Soroos does not include relinquishing freedom of reproduction in his list of approaches!

Soroos considers that each of the approaches he mentions has the potential to avert environmental tragedy. And there have been some successes, for example, with restrictions and regulations, he sites the reduction of chlorofluorocarbon (CFC) emissions to the atmosphere. Indeed the widespread agreement achieved on a response to deal with ozone layer depletion shows that the international community can work together to avert a global tragedy of the commons.

However, he notes that there were several factors working to produce the international response to the ozone problem: There was a general consensus that it would be disastrous if there was a significant ozone loss. Also the number of producers of the relevant harmful chemicals (CFCs etc) was rather small. Then it was likely that affordable substitutes for the harmful chemicals would be found, and using these the companies then producing the harmful chemicals would be able to make yet greater profits. Finally, the USA provided leadership in the international efforts. But Soroos's overall conclusion on the approaches mentioned is that they “have not been especially successful in averting the overuse or misuse of international commons". And Soroos thinks that compared with dealing with the ozone problem, dealing with climate change “poses a far more daunting challenge for international regime builders because of the continued dependence of the world's population on fossil fuels for the energy needed to achieve and maintain modern life styles”.

(Written and added to the page early January 2006)

Climate science and early warning.

There is growing concern about the harmful effects of climate change, including disruption of food production. A paper published in late October 2005 dealing with this problem, which we report on here, was referred to in the Letter that the President of the Royal Society sent to G8 leaders on the 24th of October (see our comments on this letter)

Verdin, J. et al. (2005). “Climate science and famine early warning”. Philosophical Transactions of the Royal Society Series B. doi: 10.1098/rstb.2005.1754 (published online).

“In the future, many African countries are likely to see negative impacts on subsistence agriculture due to the effects of global warming: increased temperatures and enhanced evapotranspiration, without offsetting precipitation increases. Increased climate variability is forecast, with more frequent extreme events (IPCC 2001)”. So say the authors in the introduction of their paper, where they also say: “Food security monitoring in sub-Saharan Africa is vital because the early identification of populations at risk can enable the timely and appropriate actions needed to avert widespread hunger, destitution or even famine”.

The paper explains that food security has three elements, availability, access and utilization. Availability concerns the amount and location of food in the country. However, when food is available, this does not mean that households will be able to get it. Various factors such as prices and employment opportunities (hence wages for food purchase) will together determine whether or not households obtain access to it. And food obtained may give but little benefit when people are suffering from diarrhoea or diseases like malaria; factors like availability of clean water are very important here, so the third element is utilization.

The paper states that climate monitoring and forecasting play a vital part in the attempt to achieve food security. However, both modelling and forecasting do depend on the existence of basic climatic records, and these are comparatively scarce in sub-Saharan Africa. For example, there are only about 400 rainfall stations across the African continent that report on a daily basis. And in many African countries, there is a dearth of things like data management systems and modelling capacity. Despite these problems, there have been major advances in monitoring systems and forecasting methodologies. In addition to climate monitoring in the narrow sense, satellite imagery enables assessments of the state of vegetation making use of the reflectance of plant canopies. The paper gives an overview of the techniques used in modelling and forecasting.

Now in introducing their own work, the authors draw attention to general features of climate change. Rising concentrations of atmospheric carbon dioxide (CO₂) are already observed to be correlated with increased global mean surface temperatures and the prospect is further increases in the future. This global warming threatens to undermine the stability of the whole earth's climate system, disrupting the dependent human populations and ecosystems. And Africa is no exception to this general picture. The continent has warmed during the last hundred years, and seems likely to continue to do so. And in terms of various possible future scenarios, “ Africa seems to be consistently among the regions with high to very high projected damages”.

In their own study of climate change the authors focused on Ethiopia which faces the same problems as sub-Saharan Africa. Here, as in sub-Saharan Africa, widely dispersed populations depend on rainfed agriculture (more in the highlands) and pastoralism (more in the lowlands). Both crop and pasture production are highly dependent on climate stability and especially, an adequate rainfall during the plant growing season. Most of the rains in Ethiopia come in the period March to September, with a pause in many parts of the country around the end of May - beginning of June. The rains before and after this pause period are known as the Belg and Kiremt rains respectively. As far as crops are concerned, short-cycle crops, typically wheat, teff and barley, are grown during the two rainy seasons while long-cycle crops, mainly maize and sorghum are grown throughout the whole March to September period.

The authors found that for the period 1960 to 2004, Kiremt rains have been consistent with 7-year trends staying within 50 millimetres of the long-term mean rainfall. In contrast, Belg rains have fallen off consistently since 1996, so that total Rainfall for Ethiopia also shows a downward trend in rainfall.

Now “reduced Belg rains in Ethiopia appear to be part of a larger set of climate changes in the Indian Ocean basin”. Ocean sea surface temperatures (SSTs) in the central Indian Ocean are amongst the highest in the world. Together with the summer heating of the Eurasian land mass, they help set up wind patterns that each year bring moisture to the Greater Horn of Africa (GHA), the Middle East and India. However, when the authors carried out analyses of March to May SSTs and precipitation for 1997-2004, they found “new areas of very warm water and increased convection across the southeastern Indian ocean. And they postulate that the changes in SSTs produce an anomalous circulation, which they describe and illustrate, that reduces rainfall over parts of the GHA.

This decrease in rainfall in Ethiopia since 1996 varies between regions. The northwest seems to have largely escaped the down turn. In the southwest, there has been a steady decrease in rainfall throughout the entire 1960-2004 period, not just since 1996. Rainfall is however still adequate in this region for crop production. It is the northeast and southeast regions that give cause for concern, and the southeast has actually been relatively dry since 1980.

The changes in rainfall have serious food security implications. Since 1996, there is a correlation between numbers of people needing food aid and national rainfall changes.
However, the actual impacts of rainfall change vary between areas. For the future, the largest impacts are likely to be in the northeastern and southeastern parts of the country. For these regions already have very high rural population densities, more than 100 persons per km², and relatively low water availability.

Various other factors that have contributed to the worsening food situation in Ethiopia are detailed by the authors. There have been market problems. The decline in world coffee price led to fewer people being able to cope with crop and livestock losses by working in the coffee industry. There was a bumper agricultural crop in 2000, but poor market infrastructure and lack of effective demand in food deficit areas led to a market crash in 2001; the result was that farmers responded by reducing planted area in 2002 and then the worst drought in 40 years struck. The El Nino of 1997/1998 caused floods and crop losses and an outbreak of rift valley fever. The latter caused livestock losses and a seven year livestock export ban which meant many pastoral households were unable to sell livestock to pay for cereal foods. Malaria is the biggest health problem in Ethiopia, with over 5 million malaria cases yearly, leading to high morbidity and mortality. And the high incidence of Malaria in potentially productive low-lying parts of the country discourages settlement there.

In their concluding remarks, Verdin et al say what they think needs to be done. Improved natural resources management techniques are needed to enable adaptation to new conditions. High-yielding short-cycle crops should be introduced to compensate for the poor Belg rains; this will require more research and better extension work. And the developed countries must take action now to transfer advanced climate science and technology to African counterparts.

We end this account of the paper by drawing attention to demographic factors mentioned or alluded to by the authors. They say “the country confronts a food security emergency, where 8-10 million people cannot meet the annual food needs without external assistance”. On rural resource management they say “stemming the loss of woody biomass while increasing fallow, manure applications and water conservation practices can increase soil organic carbon and lead to positive intensification of agriculture…”. Now we know that trees and shrubs have been cut down to provide fuel for cooking and land for food production, leading to soil erosion, and animal dung, instead of being used as fertiliser has been used as fuel, and fallow periods have been reduced or abandoned to allow more crop planting, all largely because the population has been growing massively – more mouths to feed.

Finally, having pointed out how malaria discourages settlement in potentially productive low-lying parts of the country, the authors go on “while the malaria-free highlands have suffered wide-spread environmental degradation, deforestation and soil erosion as the population continues to grow rapidly ” (our bold text).

Books by A. Chua and N.C. Vaca.

We are familiar with the fact that in countries with one or more ethnic minorities, throughout history, tensions have often arisen, sometimes leading to outbreaks of violence, between these minorities and the indigenous majority ethnic group. In modern times, such tensions and violence add to the difficulties of achieving truly sustainable development and thus reducing the environmental impact of the human population. Two recent books provide a fascinating commentary on aspects of this problem

Amy Chua, 2003. "World on fire". Heinemann

This book provides clear evidence that ethnic composition of a population is one important factor affecting social and economic development. Chua says that her book "is about a phenomenon - pervasive outside the West yet rarely acknowledged, indeed often viewed as taboo - that turns free market democracy into an engine of ethnic conflagration".

Chua's thesis is that the global spread of market capitalism and western style democracy is a principal, aggravating cause of group hatred and ethnic violence throughout the non-Western world. Many countries round the world have a market -dominant minority, usually an ethnic minority, and in this situation markets and democracy are not mutually reinforcing. Markets have disproportionately benefited the dominant minority, creating resentment amongst the indigenous majority. The spread of democracy, or at least the idea of democracy, has empowered the impoverished underprivileged indigenous majority to demand rights in what they regard as their land. Dominant minorities have then sometimes reacted by suppressing democracy to shore up their position, with resultant aggravation of existing tensions.

In South-East Asia, the Chinese are an ethnic minority. Chinese market dominance with corresponding intense resentment from the majority indigenous ethnic populations is, says Chua, characteristic of virtually every country in Southeast Asia. She describes how in Thailand, Malaya, Burma, the Philippines and Indonesia, Chinese dominate business, sometimes in collaboration with small cliques of ruling indigenous people. We add in parenthesis that Chua comes of Chinese stock, and is married to a Jew.

The Philippines provide a good example. Here Filipino Chinese share their market dominance with "Spanish blooded gentry". Filipino Chinese, only 1-2 per cent of the population, control most big department store chains, the McDonald's franchise, most of the major banks, and six out of the 10 English language newspapers in Manila. They are dominant in the Manila Stock Exchange, shipping, textiles, construction, real estate, pharmaceutical, manufacturing and personal computer industries.

After Suharto's rise to power, he pursued raw, globally-orientated free market policies, supported by the USA, and by the World Bank and IMF (which were effectively promoted by the USA). The result was an influx of foreign capital, unprecedented levels of economic growth, and spectacular Chinese success. The indigenous pribumi majority no doubt benefited from this growth at least in terms of average income. But their perception was of a rich group of Sino-Indonesians benefiting at the expense of the native peoples. All Indonesia's billionaires were ethnically Chinese, and almost all the country's largest conglomerates were owned by Sino-Indonesian families. The major exceptions were companies owned by the Suharto family.

By the end of the 1990s the spectacle of Suharto and a handful of Chinese cronies engorging themselves at the nation's expense provoked massive, widespread hostility. After Suharto resigned in 1998, there was an eruption of extensive and intensive anti-Chinese violence - destruction of businesses, the killing of people.

Chinese are however not the only dominant ethnic minority group in Southeast Asia. Other examples are Bengali immigrants in Assam and Tamils in Sri Lanka (formerly Ceylon). The Ceylon Tamils, historically more educated, prosperous and "advanced" than the Sinhalese majority, dominated the economy until a wave of anti-Tamil reprisals in the 1970s, and ethnic strife continues to this day.

According to Chua, Africa is the continent with the greatest abundance and variety of market dominant minorities. In West Africa there are the Ibo of Nigeria, the Bamileke of Cameroon, and other minorities in other countries. More widely in this region, the Lebanese are often a dominant minority. In Central Africa and the tiny state of Rwanda, the Tutsi minority dominated over the Hutu majority for centuries. In Burundi, the Tutsi, about 14 percent of the population, control in the order of 70 percent of the country's wealth. We have all heard of the terrible slaughters in this part of Africa. Thus in 1994 Hutus killed about 800,000 Tutsis during a three month period.

Southern African countries have been dominated by White minorities. Serious conflict broke out in each country, with the exception of Botswana. Chua writes: "In country after country, a handful of Whites engorged themselves on natural resources and human labour, creating enclaves of spectacular wealth and modernization, surrounded by mounting, justifiable hatred among the indigenous black majority". Typically, the result was "horrific violence".

In East Africa the Kikuyu, making up 22 per cent of the population dominate over the other tribes; yet here (and in some other parts of East Africa), the most significant dominating minority is the Indians. Kenya's roughly seventy thousand Indians, less than 2 per cent of the population, are dramatically more affluent than the black Kenyans around them. "A tiny handful of Asians control the entire economy" is the bitter, but not completely accurate view among black Kenyans. After the failed military coup of 1982, rioting broke out, targeting Indian shops and businesses. And subsequently further ethnic riots sometimes broke out. However, the Indian community has continued to prosper; but, says Chua, this minority finds itself uncomfortably dependent on the corrupt and increasingly authoritarian President Moi. Zimbabwe is given by Chua as an example of what he terms an ethnically targeted anti-market backlash- he refers to Mugabe's campaign against white owners of commercial farmland.

The situation in African countries however, is rarely if ever just a matter of the reaction of a majority to an ethnically dominant minority. The situation is complicated by the power of corrupt indigenous politicians, as was mentioned above for Kenya. It is also complicated by ethnic tensions and violence between indigenous populations in neighbouring regions of a country, as in Zimbabwe.

Latin America presents a slightly different situation in that since the early days of colonisation, interbreeding between White immigrants and the indigenous Amerindians has taken place, so that there has been considerable racial mixing. Generally there is not a really ethnically distinct dominant minority. Nevertheless, in general "Latin American society is fundamentally pigmentocratic: characterized by a social spectrum with taller, lighter-skinned, European-blooded elites at one end; shorter, darker, Indian-blooded masses at the other end". In some countries, the more hybrid population (mestizos) form the majority, in a few the Amerindians are still in the majority. In most Latin American countries, the light skinned, landowning (and increasingly stock owning) minority dominate the economies and have the real political power. For example, in Mexico, the most lucrative corporate sectors - oil, finance, media and telecommunications, "are controlled by a small, clubby, light-skinned market-dominant minority".

Chua concludes, however, that despite differences between Latin America and Southeast Asia, the same striking phenomenon occurs: "Like the indigenous populations of Southeast Asia, the uneducated, disease-ridden, desperately poor but numerically vast Indian- or African-blooded majorities of Latin America experience little or no economic benefit from privatization and global markets while finding themselves suddenly filled with contradictory new materialistic and consumerist desires".

While there has been less open ethnic conflict in Latin America in comparison with Africa or Southeast Asia, there has been considerable resentment against the wealthy dominant light skinned section of the population, and this has sometimes lead to violence. An aspect of this in recent years has been an increasing racial and ethnic consciousness, a spread of a sense of "Indian-ness". Chua ascribes this, at least in part, to globalization together with the demise of Marxism. While Capitalism transcends national boundaries, so does ethnic consciousness, demagoguery and anger.

Venezuela provides one good example. Since the mid 1990s there has been what Chua calls the anti-market backlash. Hugo Chavez spoke out for the 80 percent dark-skinned majority, tapping into the "collective anger and social resentments". His campaign platform was anti-market. He attacked foreign investors and Venezuela's business elite, lashed out at what he called "savage capitalism". He vowed to end the latifundia system (large agricultural estates owned by a handful of the elite). Chavez "deliberately fomented class conflict, lacing it with ethnic resentment". A landslide victory brought him to power in the country.

But Chavez's policies had a devastating effect on the economy: the wealthy Venezuelan whites whisked away more than 8 million dollars out of the country. Foreign investments were withdrawn. A coup overthrew Chavez, but soon he was back in power, to the dismay of the Bush administration.

Chua has a chapter devoted to the Middle East with the subtitle "Israeli Jews as a regional market-dominant minority". Here again the situation is different from South-East Asia in that it is not so much a question of a dominant minority in one country, but rather a dominant minority in a whole region. It is also a very complicated situation. Resentment against a market dominant ethnic minority is complicated by many other factors, as Chua is careful to point out: Religion, land distribution, issues of self-determination, a more global anti-Semitism and antisecular, anti-Western hostility. Then the situation is also complicated by the Sunni- Shi'i Muslim population divide. Nevertheless, Chua says, globalization has very disproportionately benefited the "outsider" market-dominant Jewish minority, "fuelling ethnic resentment and hatred among a massive, demagogue-incited population that considers itself the 'indigenous' 'true owners of the land'". In another chapter, Chua also deal with Jewish dominance elsewhere, this time amongst the most wealthy people in Russia.

Chua's book is a very useful source of information and a timely reminder, of the significance of ethnic composition in world affairs.

N.C. Vaca. 2004. "The presumed alliance. The unspoken conflict between Latinos and Blacks and what it means for America". HarperCollins

Nicolás Vaca makes a series of in-depth historical analyses of events in several districts of the USA, which show the competition between Blacks and Latinos for jobs, social services and education, and between White, Black and Latino candidates for council seats and mayoral office. He records too the often complex relationships between candidates and ethnic organisations, churches and the Republican and Democratic parties. In parenthesis, the book is heavy going for anyone not very familiar with the political processes in the USA, and also because Vaca sometimes uses a rather discursive style which does not always nail down particular actions to particular events/elections.

During recent decades, one might have expected that Latinos and Blacks in the USA, both minorities who had experienced discrimination, would have united to pursue a policy of anti-White domination. This has sometimes happened. However, Vaca shows that just as often such cooperation did not develop, rather there was great antipathy between Latinos and Blacks. Sometimes tensions between Blacks and Latinos boiled over into violence - Vaca discusses riots in Washington D.C., Los Angeles and Miami.

The background to, and one cause of such tensions and conflicts, was the explosive growth of the Latino population, fuelled by immigration, a growth that far exceeded the growth of the Black population. Vaca shows that while the Black population did continue to rise, the Latino population experienced explosive growth. The 1970 Census put the Latino population at 9.6 million, the African American at 22.6 million. The 1980 Census gave the Latino population as 14.6 million, the African American population as 26.5 million. The 1990 census gave the Latino population as 22.3 million, the African American as 29.9 million. The explosive growth of the Latino population continued until in January 2003, Latinos officially became the largest minority in the USA. This explosive growth of the Latino population seems to have surprised even scholars in the field, and the growth continues. As for the present, Vaca quotes Peter Brimelow at the end of his chapter on this "Latino Tsunami": "The current wave of immigration - and therefore America's shifting ethnic balance - is wholly and entirely the result of government policy".

The demographic changes led to many Blacks fearing loss of jobs to Latinos, and erosion of their social and educational amenities because of growing Latino needs for such amenities. The situation was complicated by the fact that in some districts, Blacks having established an appreciable power base in local communities, were unwilling to let Latinos into that power structure. Miami was an exception. Here it was Latinos who came to control the major political, economic and educational institutions, and their leaders appeared to have little sympathy with the plight of Blacks.

Vaca concludes that while some Black-Latino alliances exist in the USA, the presumption that simply because Latinos and Blacks are "peoples of color" they will generally put aside their differences and support each other in all endeavours, is false. The reality, says Vaca, is that a divide does exist between Latinos and Blacks, "that no amount of camouflage can hide", "that in the real world the ostensible moral and philosophical bases for coalition politics have largely fallen apart because of competing self-interests".

What is the relevance of Vaca's book to the situation in the UK? After all, there are big differences, social, political and demographic, between the USA and the UK. And it seems that actual conflicts between ethnic groups in the UK in recent decades has been primarily between poor Whites and ethnic minorities. Yet there are similarities too between the two nations. In both, immigration has played a major part in increasing the total ethnic minority population. And while in the USA in recent decades, the Latino population has grown relative to the Black population, in the UK, both the total Asian population and the total Pakistani and Bangladeshi population have grown relative to the total Black population. UK citizens reading Vaca's book, are consequently entitled to be concerned about the possible adverse social consequences of recent and current demographic changes in the UK.

Our earlier report on a publication by N. Myers.

This is one of three papers published by the Royal Society of Great Britain, originally on-line, but later in Philosophical Transactions: Biological Sciences (The Royal Society) volume 357 number 1420 (2002).

One of the other papers, by David Coleman, is used in our essay on Immigration - see our Comment and Analysis page.

N. Myers (2001) "Environmental Refugees: a Growing Phenomenon of the 21st Century".

(i) Classification of Refugees

Myer's classifies refugees into two categories. Traditional refugees are people fleeing oppression and persecution (at least 27 million in 1995). Environmental refugees are people who can no longer gain a secure livelihood because of environmental deterioration -desertification etc (at least 25 million in 1995).

(ii) The outlook for the year 2010

The population of developing countries is projected to have grown from 1995 by over one billion people - a 24% increase in just 15 years. The number of people in absolute poverty is predicted to rise from 1.3 billion to 1.6 billion. The 135 million people affected by severe desertification could well increase to 180 million. Today, 550 million people live in countries already short of water. This number is expected to swell to more than one billion. In 1985 and years following, crop yields seemed as if they might be plateauing. If they do so, there will be greater, and more widespread, shortfalls in food production; at the same time international tradable stocks will increasingly be unable to keep up with the fast growing demand.

(iii) Effects of global warming

By 2050 or earlier, rising sea levels caused by global warming may cause displacement of large numbers of people. In China, it could be 73 million, Bangladesh 26 million, India 20 million, Egypt 12 million, elsewhere including small islands 31 million, making a total of 162 million. Global warming will also cause drought and disruption of rainfall regimes; at least 50 million people could be at severe risk through such climatic dislocations.

(iv) Political instability

Increase of environmental refugees generates economic, social and political problems and can lead to conflict and violence. There are limits to a host countries' capacity and willingness to accept these people. Perceived threats to social cohesion and national identity could lead to ethnic tensions, civil disorder and even political upheaval.

Our Comment

This paper suggests to us that Europe is going to be put under increasing pressure to accept refugees.