 |
|||||||||||||||||||||||||||||||||||||||||||
|
|
Book Reviews This page was started at the beginning of September 2005. The reviews, with dates when they were put up on this web site, are as follows
“The rapid growth of human populations 1750–2000: histories, consequences, issues” gives a comprehensive account of the growth of national populations and the implications of this growth. “Scientific American and the Silent Lie” details how writers in a special issue of the Scientific American magazine put their faith in technological change for solving our climate problems, neglecting the significance of human population growth'. “Limits to growth” uses computer modelling to study the question: how may the expanding global population and material economy interact with and adapt to the earth's limited carrying capacity over the coming decades? “Collapse” explores what are the unsustainable practices that cause societies to collapse, and is based on a series of case studies. “Millennium Ecosystem Assessment” and “Sparing Nature” focus on ecosystem and biodiversity decline. We are particularly interested in how these publications regard human population growth. In our view, the first publication (which is in fact a whole series of publications) while being an extremely useful and carefully researched source of information, is seriously flawed in this respect. In contrast the second publication has what we regard as a much more balanced approach to human population growth. “The revenge of Gaia” is a study of the self-regulating system consisting of the atmosphere, living things and the ecosystems that contain them, the oceans and the underlying rocks, the system being named 'Gaia'. It shows that through the growth and activities of the human population, with the resulting increase in greenhouse gas emissions, the system is in IMMINENT danger of being destabilised. If that happens, Gaia will have one objective only - to re-stabilise, and in doing so, the needs of the human species will not be considered: if a new stable state is attained, it will be so hot that most of mankind will not survive. A very challenging book which we hope everyone will read. The review of articles in the 'Scientific American' September 2006 issue, comes not from us, but from the physicist Albert A. Bartlett. He draws attention to the fact that the articles virtually ignore the underlying cause of mankind's global warming problems, namely, human population growth. He argues that the editors and writers of the Scientific American realise the importance of population growth, so by not making this point strongly in this collection of articles, they are guilty of what Mark Twain termed the 'silent lie' — not sharing information that would help others. The reviews are arranged in the following order (from the top):
To go straight to the reviews after the first one, click on the appropriate button:
Review by Peter Salonius of the book by William Stanton (2003) “The Rapid Growth of Human Populations 1750–2000. Histories, Consequences, Issues Nation by nation.”. Multi-Science Publishing Company Ltd.William Stanton states that 'All human history is of populations expanding when resources are available and shrinking when they are not', and he predicts that 'population reduction will begin as soon as foreign aid dries up' and when basic 'carrying capacity will become critical'. If it is necessary to read the history of collective human reproductive mistakes in order not to repeat them, or to avoid continuing to make them, then this is the book that should be read by all policy makers who have anything to do with famine relief, foreign aid, fertility control education as well as immigration/greenhouse gas emission. It offers a graphical record of recent population growth as well as a brief verbal summary of the political history for every nation. Stanton's panoramic history takes us back to the transition from hunter–gathering to agriculture about 10,000 years ago when he supposes that world population may have been double the 2 million of 100,000 years ago. The Agricultural and Industrial revolutions in the mid 18th century, and the Green revolution in the mid 20th century increased the ability of society to feed greater and greater numbers. He points out that before 1750 most of the world's half billion people lived on the edge of starvation, confronted with repeated famines, and 250 years later almost five times as many survive in similar conditions. The increased food produced by the Genetic revolution in the 21st century is expected to be similarly unsuccessful in raising living standards, because the response of our species has been to produce more babies to meet the increased carrying capacity that these revolutions have facilitated. 'Darwinian' reality, with only the fittest surviving the scarcity that results when births exceed deaths, has been suspended for the last 250 years. Until the mid 18th century there was a very slowly rising population ceiling as deaths approximately equalled births. With population growth currently exceeding 80 million per year, Stanton says that 'most of the world's people are entirely unaware that they are living in an anomalous [period of ever increasing food production], which, after 250 years is approaching its end.' Historical carrying capacity, absent the temporary increase made possible by exhaustible fossil fuels, is dealt with early in the book using England as an example; from 300 BC, until coal and then oil made vastly more food production possible starting around 1750, the population approached five million several times but it repeatedly collapsed to much lower levels due to poor crop yields, tribal warfare and disease. The “Death Control (DC)” in the intervening two centuries, that has produced a ten fold population increase, has been dependent upon the increased agricultural carrying capacity and improved health care that are supported by finite exogenous geological energy stores. Stanton and a growing number of others foresee future energy scarcity orchestrating a population collapse, back to historically, solar–energy supported levels, during the next 100 years. Estimates of human numbers after the collapse vary from the 600 million that solar energy supported in 1750, to perhaps 4 billion, depending on whether global energy depletion or local factors such as water shortage, desertification, sea level rise, climate change or the overcrowding and land hunger that produce 'Violent Cutback Level (VCL)' drive the collapse. Stanton appears to define the population densities (persons per square kilometre) that result in 'VCL' by hindsight according to when and where tribal conflict, genocide and ethnic cleansing have taken place. Although population percentage growth rates are decreasing worldwide, Stanton drums home the fact that population numbers continue their inexorable and uninterrupted exponential increase due to the ever larger numbers these percentages are based upon. Relief from population pressure is provided by emigration from areas where numbers grow faster than their economies, to areas where the economy is still growing faster than the population, and by longstanding foreign aid programs and famine relief that mask the fact that the land will no longer feed the increased number of mouths. The continuing acceptance of massive numbers of immigrants and provision of food aid, by countries that are still able to produce agricultural surpluses, are seen to allow inappropriate fertility patterns to be irresponsibly maintained. Stanton is very critical of the willingness of aid agencies to take the easier course of 'saving lives' with food aid that artificially maintains reproductive strength as human populations continue to further overshoot the carrying capacity of their lands, while most of these aid providers refuse to address the more difficult issue of assistance with the birth control programs that many women are clamouring for in recipient countries. The book illuminates the concept of competitive breeding, wherein certain ethnic groups openly admit that they have a policy of maintaining irresponsibly high birth rates ('We will beat you in the beds'), designed to produce long-term political and militarily dominance, at great cost to the natural ecosystems that must support them long after current conflicts are forgotten. The author designates the last 250 years as an historically unprecedented, one–time phenomenon with 'Weak Restraints On Growth (WROG)' as escalating human numbers rapidly draw down the Earth's resources (especially non–renewable energy). He attributes much of the reluctance to deal with the 'delicate subject' of population control to the now obviously failed 'Demographic Transition Theory' of Adolphe Landry (1934), that assumed increased prosperity and food supplies would result in people having fewer children. This idea 'has persuaded decision takers and their advisors that population growth is not a serious problem because financial aid will sort it out'. If Stanton had written the book in 1960 and policy makers had taken remedial action, there might be several billion less people contributing to the global carrying capacity overshoot than there are today. He suggests that donor nations must finally realize that population control must precede attempts at poverty reduction because the other way around does not raise living standards. Stanton sees multiculturalism and massive immigration policies being feasible only when conflict to control resources is unnecessary, in countries whose populations still are growing slower than their economies. He anticipates violent 'religious', 'ethnic' and 'class' conflict to control shrinking resources as the legacy of such policies when the temporary (200 year long) 'Petroleum Interval' begins to wind down. At the end of the book, Stanton speculates that 'political correctness', 'civilized standards', current ideas about 'human rights', and the concept of 'the sanctity of human life' will disintegrate in the face of resource conflicts and massive movements of refugees from lands whose carrying capacity has been reduced by combinations of soil depletion/erosion, desertification, sea level rise and the lack of continued access to non renewable energy stores. Among grim alternatives, he foresees a return to 'quick and inexpensive corporal punishment for lesser crimes' (corporal punishment being defined as whipping, the death penalty and imprisonment), the general encouragement and legalization of 'euthanasia, abortion, and infanticide for handicapped babies' as well as the enforcement of severe restrictions on family size. Stanton hopefully speculates, as have others, that the population collapse that is expected during the 21st century will produce a smaller human society that will have 'the wit' to restrain its numbers so as to allow 'a sustainable high quality of life', at a level that is in balance with the Earth's long–term carrying capacity, and a level that may even allow some repair of an Earth that has been considerably damaged by the open–ended expansionism of the last 250 years. Reprinted from Futures, vol 38 no. 5, Salonius, P. “The Rapid Growth of Human Populations 1750–2000: Histories, Consequences, Issues” pp 630-632, copyright 2006 with permission from Elsevier. You may purchase this book at Amazon
Bartlett, A. A. (2006). “Scientific American and the Silent Lie”.The following review by Albert A. Bartlett, Professor Emeritus of Physics at the University of Colorado at Boulder, was published in The Physics Teacher, December 2006, volume 44, pages 623–624. The Physics Teacher may be accessed on line at link. Scientific American and the Silent Lie The September 2006 issue of Scientific American (SA) is a “Special Issue” devoted to “Energy's Future Beyond Carbon” with the subtitle “How to Power the Economy and Still Fight Global Warming”. As I read the issue I thought of Captain Renault, the Chief of Police in the movie “Casablanca” who says to an assistant, “Major Strasser has been shot. Round up the usual suspects”. The implication of the Chief's order is clear. Never mind finding the culprit, just “round up the usual suspects”. The main body of this special issue consists of nine articles relating to global warming, each dealing with one or more of the usual suspects. These are summarized in the first article, “A Climate Repair Manual”. There we read that global warming is a major problem: “Preventing the transformation of the earth's atmosphere from greenhouse to unconstrained hothouse represents arguably the most imposing scientific and technical challenge that humanity has ever faced. Climate change compels a massive restructuring of the world's energy economy. The slim hope for keeping atmospheric carbon below 500 ppm hinges on aggressive programs of energy efficiency instituted by national governments”. The culprit is world population growth, but SA is just rounding up the usual suspects. Some fraction of the observed global warming most certainly is caused by the release of greenhouse gases from the burning of fossil fuels. As the size of the world population increases, the rate of burning of fossil fuels increases and this can be expected to increase the rate of rise of global average temperatures. The authors of these nine articles have to know that the size of the global population is a major factor in determining the rate of release of greenhouse gases. Yet in a special issue devoted to reducing global warming, SA almost completely ignores population size and growth and instead “rounds up the usual suspects”— things we can do to reduce the human contributions to global warming such as the increased use of nuclear power and improving efficiency. The special issue contains no serious evaluation of the problems of peak production of global oil, which could happen any year now.(1, 2) There is even a hint of denial: “Even if oil production peaks soon — a debatable contention given Canada's oil sands ” (emphasis added). When one looks at the facts, one can see that production of gasoline from the oil sands won't have much effect on the peaking of world oil production. There is no serious discussion of the net energy in the production from oil sands, or in the production of ethanol from corn. It is just noted that we will have to be more efficient in these endeavors. Growth remains sacred. “But holding CO2 emissions in 2056 to their present rate, without choking off economic growth, is a desirable outcome within our grasp”. To meet the growing global demand for energy, “thousands of new power plants must be built”. “If the fleet of nuclear power plants were to expand by a factor of five by 2056, displacing conventional coal plants”, what will we do after 2056? None of the authors expresses any recognition of Eric Sevareid's law, “The chief cause of problems is solutions”.(3) Example: Nuclear power is a solution to the problem of CO2 emissions from coal burning, but nuclear power comes with its own new problems. There is a lonely isolated touch of reality in the opening sentence of the article on renewable energy: “No plan to substantially reduce greenhouse gas emissions can succeed through increases in energy efficiency alone”. The reason behind this reality is that continuing population growth, even at the level of approximately 1% per year, will likely overwhelm the annual savings that can be achieved nationally or globally through improved efficiencies. The article on hydrogen notes, “it could be decades before it [hydrogen] starts to reduce greenhouse gas emissions and oil use on a global scale”. We don't have decades. There is blithe talk about the billions and trillions of dollars that it will cost to rebuild our energy infrastructure to enable the deployment of several of the “usual suspects”. There is no serious evaluation of the impact of such costs on people and on economies. For instance, it costs about $1.50 a watt to purchase a new coal-fired electric generating plant and since utilities budget some thing like 1000 watts of generating capacity per person, every new person added to the service area of a utility costs the rate payers about $1500. So every time the population of a utility's service area grows by one percent, every person in the service area has to pay approximately one percent of $1500, or $15, just to purchase new hardware for the generation of electricity to meet the needs of new people added to the service area. The last article, “Plan B for Energy”, is prefaced with a futuristic drawing with the caption “Late 21st Century energy sources might include nuclear fusion reactors, hydrogen generated from ponds of genetically engineered microbes, high altitude wind farms [this is a new suspect], orbiting solar arrays, and wind and tidal generators, all linked to a worldwide superconducting grid”. The large electric distribution grids that span continents are enormously complex and they have the unpleasant habit of failing in massive and spectacular ways. Even more frightening is the fact that these enormous networks will be managed by people, and people will fail. I hope the future does not work out as it is portrayed in Scientific American and I don't think it will. A society that is totally dependent on high tech for the functioning of every aspect of the lives of its people is vulnerable to disruption by acts of God and acts of people. The complexities of our present infrastructure predictably lead to unpredictable failures. More complex infrastructures anticipated for the future will probably experience larger unpredictable failures. In a short essay before the main energy articles (“Lower Fertility: A Wise Investment” by Jeffrey Sachs,(4)), there is a brief mention of population. This does address population growth but in a way I found contradictory and objectionable. “Rapid population growth is not the main driver today of these [environmental] threats”. Attention should be given to “high and rising rates of resource use per person rather than to the rise in the sheer number of people”. The world's rate of consumption of fossil fuels is the product of the population size and the average per capita annual consumption. Both have to be reduced. A few sentences later Sachs writes, “Yet the continued rapid population growth in many poor countries will markedly exacerbate the environmental stresses”. So population growth is not a problem and then is a problem. But shifting the blame to the people of poor countries is the “them, not us” response that is so often encountered when population problems are discussed.(5) Sachs then presents the arguments for working to lower the fertility rates of people in “poor countries”, pointing out our funding programs to help with this would be “among the smartest investments that the rich countries could make for their own future well–being”. The idea is good. The reason given is selfish and destructive. He seems to be saying that if we reduce “their” numbers, it will be a good investment for us because there will be more resources and better lives for us. If we want to help poor people, we will be helping them increase their per capita rate of resource consumption, which, for the foreseeable future, will increase the rate of global production of greenhouse gases. Only by reducing the size of the world population can we hope to be able to give significant help to poor people. Only by reducing the sizes of populations can we have a reduction in the overall global rate of consumption of fossil fuels and the consequent reduction in the rate of production of greenhouse gases. We must lead by example by addressing overpopulation in the United States. Scientific American has rounded up the usual suspects but has ignored the perpetrator of the crime. The editors and writers at Scientific American know that population growth is the underlying source of the problems, but it is politically incorrect to state this obvious fact. Mark Twain wrote that if one has information that would help others, but does not share that information, then one is telling a “Silent Lie”.( 6 ) Because it does not address population size and growth as the main underlying cause of global warming, this issue of Scientific American is a serious “silent lie”.( 7 ) References 1. Kenneth S. Defeyes, Hubbert's Peak (Princeton University Press, 2001). 2. A.A. Bartlett, “An analysis of U.S. and world oil production patterns using Hubbert–style curves”, Math. Geology 32 , 1–17 (Jan. 2000). 3. E. Sevareid, “CBS News” (Dec. 29, 1970), quoted in T.L. Martin , Malice in Blunderland (McGraw–Hill Book Co., New York, 1973). 4. Jeffrey Sachs, Director of the Earth Institute at Columbia University and of the U.N. Millennium Project. 5. A.A. Bartlett, “Malthus marginalized”, The Social Contract 8 (3), 239–251 (Spring 1998). 6. Mark Twain, The Man That Corrupted Hadleyburg and other Short Works (Prometheus Books, Amherst, NY, 2002), p. 159. 7. A.A. Bartlett, “Thoughts on long–term energy supplies: Scientists and the silent lie”, Phys. Today 57, 53–55 (July 2004). See letters and responses, Phys. Today 54, 12–18 (Nov. 2004) and 58, 12–17 (April 2005). Reviewer: Albert A. Bartlett, Department of Physics University of Colorado at Boulder Boulder, CO 80309–0390. Copyright 2006, American Association of Physics Teachers. This article may be downloaded for personal use only. Any other use requires the permission of the author and the American Association of Physics Teachers.
Lovelock, J. (2003). “The revenge of Gaia. Why the earth is fighting back - and how we can still save humanity”. Allen Lane. | |||||||||||||||||||||||||||||||||||||||||
|
|  |
|
Millennium Ecosystem Assessment (2005). “Ecosystems and Human Well-being: Synthesis” ISBN 1-59726-040-1 & “Ecosystems and Human Well-being: Biodiversity Synthesis” ISBN 1-56973-588-3. World Resources Institute.
The Millennium Ecosystem Assessment (henceforth MEA) was conducted under the auspices of the United Nations, with the United Nations Environment Programme playing a coordinating role. The objective was “to assess the consequences of ecosystem change for human well-being and to establish the scientific basis for actions needed to enhance the conservation and sustainable use of ecosystems and their contributions to human well-being”.
The work involved took place between 2001 and 2005, and was carried out by roughly 1360 experts from 95 countries, in four working groups. It resulted in numerous reports being produced, including five 'synthesis' reports: an overall 'Synthesis' Report covering the entire work of the four working groups, and synthesis reports on biodiversity, desertification, wetlands, business and health.
This massive MEA contains a wealth of information about the nature and present state of ecosystems, how they have changed over time including the ways in which mankind has altered ecosystems, the benefits of ecosystems to mankind, and present options for maintaining ecosystems. This is a very wide field of enquiry and I will not attempt a comprehensive review. Rather, bearing in mind the focus of Gaia Watch on population growth, I will focus on the decline of ecosystems and biodiversity, and the role the MEA perceives human population growth has had as a causal agent of this decline and may have for policies designed to mitigate this decline in the future. I will further restrict my review by only dealing with the main Synthesis report and the Biodiversity Synthesis report, apart from referring very briefly at the end to the report of one of the four working groups. This review should be read in conjunction with the review of McKee's book which follows the present review.
Before we get down to the analysis of what the reports say, there are three preliminary matters to mention.
(1) The term 'drivers of change' is used in the reports, where it is defined as follows:
“Natural or human-induced factors that directly or indirectly cause a change in an ecosystem are referred to as 'drivers'. A direct driver unequivocally influences ecosystem processes. An indirect driver operates more diffusely, by altering one or more direct drivers”.
(2) Words used in the reports to indicate judgmental estimates of certainty are:
very certain (98% or greater probability)
high certainty (85-98% probability )
medium certainty (65-85% probability)
low certainty (52-65% probability)
very uncertain (50-52% probability).
(3)The MEA includes four scenarios which were produced to explore possible future changes in ecosystems and human well-being, depending on sets of assumptions about driving forces. So they are not predictions of what will happen in the future.
And now to begin the review.
A figure in the Preface of the Synthesis report (which is given again in the Preface of the Biodiversity Synthesis report) gives the conceptual framework for the whole MEA. It is reproduced here by kind permission of the World Resources Institute.
To enlarge the small (thumb-nail) image, click on MEA immediately beneath it. To complete the enlargement you may have to click again on the partly expanded image or on the little box icon that appears in the image. To then toggle back to this page right-click with your mouse.
|
This diagram is a useful typology (classification of factors). Now our central concern in Gaia Watch in regard to ecosystems, is the influence of human population growth on deterioration of these ecosystems and the concomitant loss of biodiversity; and in this diagram, population growth is subsumed in 'Demographic', one of the Indirect Driver of Change (top right box). So we are particularly interested in the way that the MEA traces out the influence of demographic factors in the total analysis, and we return to this later.
The MEA has 'four main findings', stated in the Synthesis Report as follows:
- Over the past 50 years, humans have changed ecosystems more rapidly and extensively than in any comparable period of time in human history, largely to meet rapidly growing demands for food, fresh water, timber, fibre, and fuel. This has resulted in a substantial and largely irreversible loss in the diversity of life on Earth.
- The changes that have been made to ecosystems have contributed to substantial net gains in human well-being and economic development, but these gains have been achieved at growing costs in the form of the degradation of many ecosystem services, increased risks of nonlinear changes, and the exacerbation of poverty for some groups of people. These problems, unless addressed, will substantially diminish the benefits that future generations obtain from ecosystems.
- The degradation of ecosystem services could grow significantly worse during the first half of this century and is a barrier to achieving the Millennium Development Goals.
- The challenge of reversing the degradation of ecosystems while meeting increasing demands for their services can be partially met under some scenarios that the MEA has considered, but these involve significant changes in policies, institutions, and practices that are not currently under way. Many options exist to conserve or enhance specific ecosystem services in ways that reduce negative trade-offs or that provide positive synergies with other ecosystem services.
The changes that have taken place make dismal reading. Virtually all of the ecosystems of the globe have now been dramatically transformed by human activity. As the first mentioned 'main finding' indicates, most changes have been made to meet what has been a dramatic growth in the demand of food, water, timber, fibre and fuel. Thus we find:
“Between 1960 and 2000, the demand for ecosystem services grew significantly as world population doubled to 6 billion people and the global economy increased more than six fold. To meet this demand, food production increased by roughly two-and-a-half times, water use doubled, wood harvests for pulp and paper production tripled, installed hydropower capacity doubled, and timber production increased by more than a half”. For example, more land was converted to cropland in the thirty years since 1950 than had been converted in the whole of the period 1700 to 1850. Increased hydropower involved the flooding of vast areas of vegetated land - the amount of water impounded behind dams quadrupled since 1960.
At least one quarter of important commercial fish stocks are over-harvested (category 'high certainty'). From 5% to 20% of global freshwater use now exceeds long-term accessible supplies and is now being met by either engineered water transfers or “overdraft of groundwater supplies” (low to medium certainty).
As for the future, it is thought that about 10 to 20% of current grassland and forestland will be converted to other uses, mainly agriculture and expansion of cities and infrastructure, between the present and 2050. And more generally, as the Biodiversity Synthesis Report page 5 euphemistically puts it in relation to the scenarios of possible future change “all scenarios explored in the Millennium Ecosystem Assessment project continuing rapid conversion of ecosystems in the first half of the twenty first century”. Further (finding 6 page 14), “unprecedented additional efforts would be needed to achieve, by 2010, a significant reduction in the rate of biodiversity loss at all levels”.
We are warned that some changes in ecosystems are nonlinear: “once a threshold is crossed, the system changes to a very different state. And these nonlinear changes are sometimes abrupt; they can also be large in magnitude and difficult, expensive, or impossible to reverse”. One of the examples given concerns regional climate change. The report notes how deforestation generally leads to a decrease in rainfall. And “since forest existence crucially depends on rainfall, the relationship between forest loss and precipitation decrease can form a positive feedback, which, under certain conditions, can lead to a nonlinear change in forest cover”. And to climate change I now turn.
The Biodiversity Synthesis Report notes that recent climate change, has already had significant impacts on ecosystems and biodiversity. And Climate change is projected to have various adverse effects in the future:
- Exacerbation of biodiversity loss (medium to high certainty)
- Reduction of water availability in arid and semi-arid regions (high certainty)
- In some regions reduction of reliability of hydropower and biomass production (high certainty
- Increased incidence of some vector-borne diseases in many regions (medium to high certainty), increased heat stress mortality (high certainty) etc.
- Reduction of agricultural productivity in the tropics and sub-tropics (low to medium certainty)
- Combined with land use change and spread of alien species, limitation of species to migrate and ability to persist in fragmented habitats (no 'certainty' stated)
The Biodiversity Synthesis Report also tells us that during the last few hundred years man has increased species extinction rate by as much as three orders of magnitude. This assessment is only given a 'medium certainty' status for a variety of reasons - we cannot of course know the extinction rate of species not yet found and described, the status of many species that have been described is poorly known, and it is very difficult to be certain about the final extinction of species that were very rare anyway. But based on recorded extinctions of known species over the past 100 years, extinction rates are about 100 times greater than rates characteristic of fossil record species, although some estimates put extinction rates 1,000 to 10,000 times higher than in fossil record lineages. Considering well studied 'higher' taxonomic groups, between 10% and 50% of mammals, birds, amphibians, confers and cycads are currently threatened with extinction.
Among a range of 'higher' groups of organisms, most species are currently declining. This applies to amphibians globally, African mammals, birds in agricultural lands, British butterflies, Caribbean corals, water birds and fishery species. But one needs to consider more than just the decline in the numbers of a species. The many species that human activities have caused to decline tend to be replaced with a much smaller number of expanding species which thrive in environments altered by man. The global outcome is a more 'homogenized' biosphere with lower species diversity.
Decline and extinction is not evenly spread over all ecological or taxonomic groups. Thus species facing a high rate of extinction tend to be at higher trophic levels, have low population density, long life span, low reproductive rate and small geographical range. Also, the degree of extinction risk tends to be similar for related species, which means that whole evolutionary radiations (genera, families) can and have been lost.
All these changes have great significance for genetic diversity, which has declined globally; with domesticated plants and animals there has been a 'substantial' reduction in diversity.
Thinking in terms of 'human benefit', there have been large benefits from actions that have caused homogenization and loss of biodiversity. Thus agriculture, fisheries and forestry “have often been the mainstay of national development strategies, providing revenues that have enabled investments in industrialization and economic growth”. However, such national benefits have not been distributed in an equitable way amongst people:
“Even where the net economic benefits of changes leading to the loss of biodiversity (such as ecosystem simplification) have been positive, many people have often been harmed by such changes. In particular, poor people, particularly those in rural areas in developing countries are more directly dependent on biodiversity and ecosystem services and more vulnerable to their degradation”. And there are trade-offs between ecosystem services. For example, aquaculture farmers may prosper, but by practices which increase soil salinization and thus reduce the rice yield of other farmers and threaten food security for subsistence farmers in the area.
Now how is human population growth regarded in the MEA?
To make an assessment we will first of all consider the Synthesis report. In several places the MEA does recognise harmful effects of human population growth. For example, the report at one point notes how both economic growth and population growth lead to increased consumption of ecosystem services, although actual adverse environmental impacts “depend on the efficiency of the technologies used in the production of the service” (page 64). Here the authors seem to have in mind the famous impact equation I=PAT: Environmental Impact equals Population times Affluence or Consumption times Technology, although they do not mention this equation. They go on “Driving forces are almost always multiple and interactive, so that a one-to-one linkage between particular driving forces and particular changes in ecosystems rarely exist. Even so, changes in any one of these indirect drivers generally result in changes in ecosystems”.
Now this last quotation comes from a section entitled: “What are the most critical factors causing ecosystem changes?” and a subsection on the indirect drivers. The authors re-iterate that there are five major sets of indirect drivers: demographic, economic, sociopolitical, cultural and religious, science and technology. Now one might expect that for each driver set they would say something about the drivers, but then go on to say something about how these drivers affect the direct drivers. Now this is what we find for the last four mentioned indirect driver sets. For example, with economic drivers we read that taxes and subsidies are important indirect drivers of ecosystem change, and an example given concerns fertilizer taxes that “provide an incentive to increase the efficiency of the use of fertilizer applied to crops and therefore reduce negative externalities”. And in the bit on cultural and religious drivers, we read cultural differences clearly have important impacts on direct drivers: “Cultural factors, for example, can influence consumption behaviour...and they may be particularly important drivers of environmental change”. But with the first mentioned indirect driver set, demographic drivers, all we are given are some facts about population growth and migration. There is nothing at all said about the effects of these drivers!
As mentioned earlier, four Global Scenarios to explore possible future changes are developed in the MEA. These vary from each other in matters like the extent of promotion of global trade and economic liberalisation, the extent that global treaties (e.g. on climate change) are implemented and the extent that ecosystem management is proactive as distinct from mainly reacting only to problems once they have become obvious.
In developing these scenarios, human population growth seems to be recognised as a significant factor since demographic assumptions are made for each scenario (fertility, mortality and migration); and in one scenario ('Global Orchestration') we read “The expansion of abrupt, unpredictable changes in ecosystems, many with harmful effects on increasingly large numbers of people, is the key challenge facing managers of ecosystem services”. However, not one scenario includes the situation where any policy is developed directed at reducing population growth through the spread of contraceptive services or the adoption of measures of coercion (e.g. using taxes to promote lower fertility). Yet in our view, such policies aimed at reducing population growth would make a very massive difference to any attempt to conserve ecosystems and improve human well being. Indeed we agree with McKee (in his book which is dealt with below), that we need to take steps to curb population growth. And we believe that unless this is done, no amount of other action will effectively halt the decline in ecosystems, the extinction of species, and the improvement of human well being.
There is one more major section in the Synthesis Report where we might reasonably expect something to be said about the need to take steps to reduce population growth, and this is section 8 of “Key Questions in the Millennium Ecosystem Assessment”, a section entitled “What options exist to manage ecosystems sustainably?”
This is a large section (nine pages) which gives many options (referred to as 'promising interventions'). These options are grouped under headings such as Institutions and Governance, and Economics and Incentives. None of the specific interventions mention population policy or population control. In fact the only statement which does so in the whole section is in the introductory paragraph of the Social and Behavioural Responses sub-section:
“Social and behavioural responses - including population policy; public education; empowerment of communities, women and youth; and civil society actions - can be instrumental in responding to ecosystem degradation”. But nowhere is 'population policy' enlarged on.
Overall, we can see that the MEA, as summarised in the main Synthesis report, treats population growth as a given, something that has harmful effects, effects we should try to ameliorate, but they do not go on, in this summary report, to specifically advocate action to control and reduce population growth. They nearest they get to this is on p.19 where we read:
“Ecosystem degradation can rarely be reversed without actions that address the negative effects or enhance the positive effects of one or more of the five indirect drivers of change: population change (including growth and migration), change in economic activity (including economic growth, disparities in wealth, and trade patterns), sociopolitical factors (including factors ranging from the presence of conflict to public participation in decision-making), cultural factors, and technological change”. Then once again the authors point out the interaction between population growth, consumption and technology and go on “too often, actions to slow ecosystem degradation do not address these indirect drivers”. Then they give an example. Will they involve population growth in their example? Well here is the example:
“For example, forest management is influenced more strongly by actions outside the forest sector, such as trade policies and institutions, macroeconomic policies, and policies in other sectors such as agriculture, infrastructure, energy, and mining, than by those within it”. No, the example does not mention population growth. One gets the impression the authors shy from suggesting any need to develop population policies.
I now turn to the Biosynthesis Report to see how human population growth is regarded there.
Again, human population growth is acknowledged as a cause of biodiversity change. On page 8, in the section entitled “What are the causes of biodiversity loss, and how are they changing?” and the opening paragraph on indirect drivers, we read “in particular, growing consumption of ecosystem services (as well as the growing use of fossil fuels), which results from growing populations and growing per capita consumption, leads to increased pressure on ecosystems and biodiversity”. So we see human population growth linked with growing consumption. And on page 13 we find this expanded to the full I=PAT formulation by including technology:
“Consumption of ecosystem services and nonrenewable resources affects biodiversity and ecosystems directly and indirectly. Total consumption is a factor of per capita consumption, population, and efficiency of resource use. Slowing biodiversity loss requires that the combined effect of these factors be reduced”.
Note how population is shifted from its first position in I=PAT, to second position. But at the same time, this statement could be interpreted as hinting there is a need to slow population growth. But I do not think the authors actually have this in mind. And I note that this statement is in a major section of the report “What action can be taken?” This consists mainly of a long bullet point list in which the above statement comes in a bullet point “Addressing unsustainable consumption patterns” which is only item 15 out of the total of 20 items. Later in the report is the major section 3 “What are the current trends and drivers of biodiversity loss?” and a subsection “drivers of biodiversity change and their trends” where we read (page 47):
“Changes in biodiversity and in ecosystems are almost always caused by multiple, interacting drivers. Changes are driven by combinations of drivers that work over time (such as population and income growth interacting with technological advances that lead to climate change) or level of organization...”. And on page 49, at the beginning of a subsection on indirect drivers, we see population growth being given a significance greater than in any of the other sections I have so far quoted from or mentioned:
“Biodiversity change is most clearly a consequence of the direct drivers. However, these reflect changes in indirect drivers - the root causes of changes in ecosystems. These can be classified into the following broad categories: change in economic activity, demographic change, sociopolitical factors, cultural and religious factors, and scientific and technological change” (my italics), although I note again demographic factors (which is where human population growth fits in) are given second place (to economic factors).
But now lets put this in the perspective of the amount of space this section gives to indirect drivers and direct drivers. The former gets less than half a page, while direct drivers get several pages before the section drifts into discussing indirect and direct drivers together!
There is one more major section in the Biosynthesis Report where it could have been proposed that efforts should be made to curb human population growth, and that is section 5 “What response options can conserve biodiversity and promote human well-being?” of the “key questions” part of the report. This section corresponds to section 8 in the Synthesis Report I have already referred to.
Again the significance of indirect drivers is stated, right at the beginning of the section (page 69), where after briefly writing on direct drivers we find “However, these drivers are better seen as symptoms of the indirect drivers, such as unsustainable patterns of consumption, demographic change, and globalisation”. But why did they not be more specific and state “such as unsustainable population growth”!
On page 73 we read “indirect drivers like globalisation and international decisions on trade and economics often have a negative effect on biodiversity and should be addressed at the international level...”. But the authors do not mention the indirect driver human population growth. Then on page 81 we read:
“Addressing the indirect drivers of change may also require somewhat longer time horizons given political, socioeconomic, and demographic inertias. Population is projected to stabilize around the middle of the century and then decrease. Attention also needs to be given to addressing unsustainable consumption patterns”
This is clear evidence of my contention that the MEA regards human population growth as a given, not as something requiring intervention. “Attention also needs to be given to addressing” - but they have not 'addressed' population growth, they have simply stated it! And note that even if the population does stabilize around the middle of the century, it will probably have increased by roughly a third - an increase of roughly 2.5 billion.
My overall conclusion on the attitude of the MEA to human population growth is then, that this growth is regarded only as a fact, a 'given' to which mankind must adapt its strategies. It is not something that requires active intervention to mitigate ecosystem and biodiversity loss successfully. And in my view, this is a fundamental flaw in the MEA. Bearing in mind that governments around the world no doubt regard the MEA as authoritative, and if human population growth has the significance I believe it has, the MEA may do more harm than good by failing to point out, by distracting attention away from, the need to control the human population. I agree with the conclusion of McKee (next review below) that there are twin requirements for a strategy to effectively mitigate ecosystem decline. One is active conservation of the natural world; the other is to practice human population control.
Nevertheless the MEA project was a herculean task which, as far as I can tell from my limited investigation, and with my additional qualification about the role of human population growth, was well carried out. The MEA reports are clearly a very valuable source of information for ecologists and policy makers; a brief perusal of the main working group reports shows that just the many references at the end of the chapters justify that conclusion. And although I have criticisms of the policy responses, the report of the working group on policies mentioned in the footnote below, with its analyses of constraints to policy making, will be invaluable for policy makers.
Footnote
There is one report highly relevant to an evaluation of the approach of the MEA to population growth that I have not mentioned, although it must be pointed out that the overall Synthesis Report does take this report into account. This is the report of one of the four working groups, the Responses working group, with the title “Ecosystems and Human Well-being: Policy Responses”.
This is an extremely long (636 pages!) discussion of types of response, responses at different levels (local, national, international) how responses interact, what are the 'enabling' factors, and the 'binding constraints' that make policies feasible or infeasible, past policy responses and the potential for new responses. However as I expected having studied the main Synthesis Report, I could not find any clear advocacy of population policies in this report.
John Barker
You may download the synthesis reports at no cost. Bear in mind that downloading large reports takes quite a long time.
Download the overall Synthesis Report * Download the Biodiversity Synthesis Report * You can buy the Synthesis Report (paperback) from Amazon. *
You can buy the Biodiversity Synthesis Report (hardcover) from Amazon.
The other reports of the MEA may be purchased from Island Press * or they may be downloaded by chapter, clicking on "View chapters".
To return to the top of this page click this button:
|
| |
|
McKee, J.K. (2003). "Sparing nature. The conflict between human population growth and earth's biodiversity". Rutgers University Press.
ISBN 0-8135-3141-1
This is an important book on an important subject, and I think it is appropriate to attempt to summarise the author's argument in detail. I put my critical comments at the end in a separate section. So this review has two sections, content and critical comments.
Contents
McKee starts in Chapter one with two propositions. The First is that "there is a very close relationship between biodiversity loss and human population growth". He immediately goes on to assert a causal connection between these two phenomena: "Quite simply, the more people there are, the more we push aside wild plants and animals. As our population has grown, other species have had to adapt to living in confined reserves or enclaves, lest they go extinct. But over the planet as a whole, there are fewer chances for species to survive as we continue to increase our numbers so dramatically, with a net gain of over 200,000 people every day". The second proposition is "the most important conservation measure we can take is to slow or halt the growth of the human population".
In chapter two McKee introduces, and in chapter three develops, an idea that Charles Darwin used to illustrate natural selection: nature may be thought of as a yielding surface into which very many sharp wedges are driven in close together. Sometimes as one wedge is struck, another one falls off. Normally the wedges are conceived as being variant races within a species. But the idea can be extended to think in terms of more and less successful species. And to McKee, the human species is the most successful wedge of all. And he applies the idea straight away to the evolution and spread of the genus Homo.
McKee argues that the evolution of man in Africa and spread to other parts of the world is correlated at each stage with mass extinctions of other mammal species. In Africa itself, after the appearance of Homo erectus, other African mammals started to go extinct at an unprecedented rate. Outside of Africa, the spread of H. erectus and later Homo sapiens to and in the different continents was associated with mass extinctions of large mammals. McKee provides evidence to support his contention that the spread of Homo was the primary cause of the mass extinctions, although he accepts that climate change played a part.
In Chapter four McKee discusses the possible relationships between the spread of agriculture and biodiversity decline. But first he addresses the issue - what was the relationship between human population growth and the development and spread of agriculture?
Based on an estimate of global population growth rate in the thousands of years before the industrial revolution, McKee constructs a graph of population growth from 100,000 years ago to the present. This graph shows the familiar exponential growth curve.
Now he places the origins of agriculture at around 10,000 years ago in the Middle East, around 8,500 to 4,000 years ago in other regions of the world. "In terms of geological time, it all happened in a blink of an eye". And it is around 10,000 years ago that "the population numbers start to take off dramatically". McKee argues that this accelerated take off was basically just a consequence of the nature of exponential growth rather than being caused by the development and spread of agriculture. Nevertheless while not accepting the simplistic notion that it was the introduction of agriculture that caused the accelerated upswing in the population growth curve, this introduction was part of a feed back loop which caused the accelerated population growth: Population growth spurred the origins of agriculture, and agriculture fuelled population growth.
McKee argues that the development of agriculture inevitably led to loss of biodiversity:
The development of agriculture is the story of the more efficient capture/concentration of energy for food production. Take for example clearing forests to create agricultural land. A forest is much better at assimilating energy from the sun than is a field of corn. A basic reason for this is the much greater biodiversity in forests compared with fields of crops:
"Tall trees gather most of the sunlight, but plants in other levels of the forest are adapted to produce with less sunlight. The ecological interactions of many plants and animals maximize the assimilation of energy from the sun and nutrients from the soil". The trouble is that the forest is not as good as a field of corn "at producing concentrated foods for human consumption". In more general terms, agriculture necessarily reduces biodiversity - a large field with a single crop has little diversity of either species or genes; soil fauna is also less diverse.
McKee goes on briefly to consider ancient civilisations. Agricultural activities led so often to a reduction of the productive capacity of soils through soil erosion and soil salinization. While the collapse of some ancient civilisations seemed to occur at times of 'climate downturns', McKee argues that it was a combination of population pressure and climate change which brought about collapse.
McKee ends his chapter by noting that "further increases in agricultural land must necessarily result in habitat destruction, just as has been the case since the origins of agriculture ten thousand years ago". Based on the work of Tilman and colleagues, if past trends continue, by 2050 the amount of agricultural land needed will be 18 percent more than it was in 2000. This represents the world-wide loss of natural ecosystems of an area larger than the United States.
Chapter five begins, in effect, with a short very elementary course on the processes controlling population growth (demography). Fertility and mortality are the prime determinants of population size change, but for any region of the globe, migration is also a determinant. McKee goes on to explain the importance of the age structure of populations and also gives an account of the 'demographic transition'. He enlarges on exponential growth and uses saving for retirement to illustrate the basic principle. People put in the same amount of money each year at the same interest rate, to build up their retirement funds. "More money makes more money as each year you add to the principal; likewise, people produce more people, regardless of the growth rate. It is compound interest".
Exponential growth produced the accelerated increase of the human population, which he then details. Most fundamentally, he notes that it took 100,000 years for the human population to grow to three billion - the 1960 population size, although nearly half that number had been added only very recently - since 1900. But then it only took 39 years to double the population to six billion - sometime in 1999. And to help us to understand just how massive population growth currently is, he writes that it takes only 38 days for total world population to increase by a number equal to the present population of New York City!
Global population growth continues. And United Nations projections suggest growth will continue until population size reaches eleven billion people around AD 2200, by which time the point of zero population growth would have been reached. That is a massive further increase. But long term projections, both in terms of the largest population size that will be reached and the timing of that event are very unreliable. Much depends on the extent that the 'demographic transition' takes place across the world.
McKee explains, as we also explain in the global section of our Population Trends page, in presently industrialised countries, the population growth rate increased over many recent decades (McKee says from 1850 but we would put the start much earlier). McKee discusses this in terms of the demographic transition and the timing in that transition of mortality and fertility decline. Now while mortality rate in 'developing countries' has generally declined, and fertility rate has declined considerably in some of these countries, in others there has been little reduction in fertility rate. Further, it is uncertain whether or not the demographic transition will be completed in developing countries, yet it is in these countries where most of the present population growth is taking place.
McKee comments on the significance of continued population growth for other species on the planet. His concern is that species not already 'squeezed out' by our large population, will be driven to extinction by the massive wedge of eleven billion people. Certainly, a human wedge of this proportion "can only have negative consequences for biodiversity".
He explains his concerns by considering the global allocation of land for various purposes, based on an analysis by J. Cohen. He lumps together marginal environments such as the arctic, and land already covered over in buildings or used for reservoirs and recreation, as 'nonarable' land, land useless for agriculture, which he says takes up 72% of the world's surface. The remaining land can be divided into three categories - 'food' (12%) 'wood' (land needed for wood used in cooking or in building)(4%) and 'fallow' (the remaining land, which is where most species live) 12%. This does not look too bad as far as biodiversity is concerned. But if the world population grows to eleven billion, much more land will be needed for food (22%) and for wood (7%) and there will be no 'fallow' land left. And "we need fallow land for nature to conduct all its tasks of regeneration. We need other species to conduct those services - decompose wastes, recycle carbon, build soil, produce the oxygen we breathe, and so on". So McKee writes that the really important question is not 'how many people can the earth support?', but, rather, 'how many people can the earth sustain?'.
McKee then goes on in this chapter to get to the heart of the matter - the relationship between human population growth and biodiversity loss. He prefaces this section with information about recent extinctions and estimates of future extinction rates. And he also notes that out of all known plant species on the planet, at least one in eight is threatened with extinction or near extinction.
McKee's account of the attempt to find out if and to what extent human population growth correlates with and may cause biodiversity loss reads like a detective story. The work was done primarily on mammals and birds since we know more about the species of these groups than in most other groups.
It seemed obvious at the start that countries with relatively high human population growth rates would have more threatened species. But no such correlation was found by investigators. However it was then found that another factor besides just growth rate must be taken into account.
For there may be countries included in the analyses which have high growth rates, but there were few people there to begin with so that the high growth rate, at least for some time, may have little effect on species diversity. So investigators then decided population density might be a better variable to investigate. Sure enough, the new analyses, still working with the two most comprehensively studied groups, mammals and birds, did show a statistically significant correlation between human population densities and the number of threatened species.
However, further analysis showed that the strength of the correlation relied heavily on data from island countries. "Islands tend to quickly acquire dense populations, and animal diversity is quickly squeezed out by the 'weed mammal' humans". Restricting the analyses to continental countries, the correlation was weakened.
Further examination of available data introduced other complexities into the story. For example, investigators found that there was some correlation between the number of threatened animal species and average country temperatures. And human densities and fertility rates were correlated with other climatic variables. Nevertheless, when all the various complicating factors were taken into account in the statistical analyses, the conclusion was that "there is an undeniable relationship between human population density and the number of animal species threatened". And country population densities were found to be able to account for about 40 percent of the variability in the number of threatened animal species.
The question then arises, how to account for the remaining 60 percent? Investigators then tried out various statistical models to see which had the greatest explanatory value. They finally found that a model which just used human population density and number of species in a given area (species richness) accounted for 88 percent of the variability "in the relative frequency of threatened species across continental countries".
What then does this tell us about future changes? McKee suggests the average country will have a 14 per cent increase in threatened species by 2050. This is equivalent to four species per year. And McKee points out that in terms of evolutionary time, 50 years is just a brief moment in time.
McKee goes on to discuss what are known as global "hot spots". These are defined as "areas featuring exceptional concentrations of endemic species and experiencing exceptional loss of habitat". There are 25 of these hot spots, where 44 percent of all known plant species and 35 percent of known vertebrate animals are found.
But these hot spot areas are threatened. Taken together, only 12 percent of the hot spots' original areas remain relatively undisturbed. Further, with hot spots, human population growth rates are on average 1.8 percent annually, compared with a global average of 1.25 percent. Many of the hot spots are in tropical, warm, wet regions, and such conditions seem to promote human fertility.
Growing human populations may adversely affect biodiversity in hot spots and other areas in a variety of ways. It may be that an important oil field is discovered in a hot spot area and politicians wish to see it exploited. The Wolong Nature Reserve in China is meant to protect the giant panda. But since the reserve was established in 1975, the human population increased by 70 percent, and the number of households more than doubled. Unfortunately, the best terrain for the panda is a popular source of firewood for the human population, so the panda's habitat is being degraded.
McKee sees the only solution to the problem of global conservation is to stem the growth of the human population.
In chapter 6 McKee goes on to consider habitat loss throughout the world and its consequences for biodiversity. The gradual reduction of total habitat sizes leads to reduction in biodiversity. But it is not just the reduction of total area of given types of habitat that is the problem. The problem is also habitat fragmentation.
Habitat fragmentation leads to reduction of biodiversity in a number of different ways:
- Many animals cannot find enough food, let alone mating partners in remnant patches of their former environment. This is particularly true of large carnivores like the wolves and jaguars. They need meat, and need to range quite widely to get enough of it.
- Habitat fragmentation tends to lead to populations of species getting packed into tighter quarters, making it easier for disease to spread.
- Dividing up habitats into fragments increases habitat edges. Such edges have a distinctive floral and faunal composition. In general they tend to harbour fewer species, so there is usually a loss of biodiversity within these areas. But not only that. Secondary growth of less diverse weedy vegetation takes over on disturbed edges. But these species are often invasive, and this secondary growth often gradually leads to the forest edge receding.
There is a corollary from the effects of habitat fragmentation for conservation:
"Whereas saving small patches of land is a noble endeavour, it is thus not a sufficiently promising strategy for maintaining biodiversity, particularly for species who need lots of space. More propitious results would come by keeping the human population from spreading into those lands in the first place".
Chapter seven focuses on water, and the many ways that human populations have reduced species biodiversity by water-related activities. For me, this is one of the most telling chapters in the whole book.
He starts with an impressive example of the effects of overpopulation, by turning to one of the world's major rivers, the Yellow River in China. Each year since 1985, the river has run dry for part of the year. And in 1997 it failed to reach the sea for 226 days. The main reason is that on its way to the sea, the river's waters are diverted into fields for agriculture and into the growing cities for consumption, sanitation and industry.
He details the adverse effects of building dams. The most basic effect is simply that if you divert water for human needs, you reduce the amount of water available for other purposes such as the support of wildlife. Also, dams involve the flooding of large land areas. Since dams are not built in densely populated areas, this means that what is lost is areas where other species can live.
Building dams, and increased withdrawals of water from rivers, has had a devastating effect on biodiversity. More than 20 percent of all freshwater fish species are now endangered because dams and water withdrawals have destroyed the free-flowing river systems where they thrive. Worldwide, 26 kinds of salmon are threatened with extinction, with further threats to their genetic biodiversity.
Man's pollution of lakes and rivers has increased as human populations have increased. Many years ago with many lakes, one might safely drink the water, but this is no longer so. More and more people swimming in the lakes and doing other things as well have increased the lakes' bacteria populations. Runoffs of fertilisers from agricultural lands also make the water unsafe to drink, and combined with the run off of soils, lead to the eutrophication of lakes (and rivers). Trees are cut down by lakes, for camp sites, scenic highway, etc. This reduces leaf fall that feeds micro-organisms which form the base of lake ecosystems. But this also removes shade which minimises temperature variation, so important for those plants and animals that live close inshore. And industrial pollution causes increase in temperatures - thermal pollution.
Increased use of waterways for transport and pleasure has led to the spread of many species which hitchhike on vessels. This not only leads to the increasing 'homogenization' (loss of between area species diversity) of the world's water fauna, but allows the spread of species which, proliferating in the new environments, disrupt local ecosystems.
Oceans have suffered from increased fishing to provide food for the ever growing human population. McKee thinks over fishing has been more destructive of ecosystems than pollution and habitat destruction. He notes that large mammals that rely on fish are in competition with humans for food and have now largely abandoned coastal regions world wide. The effects of over-fishing, carry on down the food chain. People tend to take the larger fishes at the top of the food chain, "so the initial effect is a decline in their populations, sometimes past the level of survivability. Once one species is gone, other similar predators become the target of over fishing. The big fish eat the little fish, so a decline in the number of aquatic predators leads to a burgeoning of the populations at lower trophic levels. These populations then become more dense and are more subject to outbreaks and the rapid spread of disease".
Fish farming has increased greatly. Some people hope that we may get sufficient protein from such farming to successfully feed the growing human population. But as McKee observes, "there ain't no such thing as a free lunch": the farmed fish need food. And ultimately this comes from the phytoplankton of the ocean, thus reducing the food available for wild coastal animal populations. Some farmed fish are fed smaller fish. But where do they come from? Largely from wild populations. And "many intensive and semi-intensive aquaculture systems use 2-5 times more fish protein, in the form of fish meal, to feed the farmed species than is supplied by the farmed product".
McKee turns to the issue of total human water consumption and available supplies. He believes that as human populations continue to grow, there will not be enough to go round. Already man uses about half of the earth's usable fresh water. And by 1995 a third of the human population was living under conditions of relative water scarcity.
McKee concludes there is only one "sustainable solution" - stop the growth of the world's human population.
In chapter 8 McKee turns to conservation and tries to show why conservation is important for the future of mankind. And he attempts to show that "our pension plan for nature must include a diverse portfolio".
He focuses first on tropical forests. These have high species diversity and make up the majority of the world's hot spots. But "the value of tropical forests is not just the high species diversity that characterizes such parts of the world, but the vital services such ecosystems perform, which are necessary for preserving the way of life of people like us, living thousands of miles away".
Tropical forests, together with boreal (and other) forests, extract carbon dioxide from the atmosphere, converting it into the materials of their bodies - they are 'carbon sinks', mitigating global warming. And when we burn down forests to make way for agriculture, we release most of the stored carbon back into the atmosphere as carbon dioxide.
Whereas forests absorb heat, denuded patches of earth heat up, causing localized areas of dry heat that can disrupt regional weather patterns. But forest trees also pull up water from the soil and transpire it back into the atmosphere, making rain clouds. Without trees and other plants to recycle water, areas like the Amazon basin would lose significant amounts of rainfall, as would other parts of Brazil where crops are grown.
Natural grasslands also act as a carbon sink, but unlike forests, most of the carbon is stored in the soil. And natural grasslands are more effective than farmed fields at absorbing rather than reflecting solar energy. And the extensive root systems reach deep down into the soil reaching water that is then transpired into the atmosphere. "Thus the world's climatic regime is held in check, at least in part, by the natural services of grassland ecosystems".
There has been much soil erosion on farmlands across the world, caused by tilling, planting monocultures, overgrazing and trampling by cattle. "Not so in natural grasslands, which have perennial root systems that nurture the soil and prevent its erosion. Indeed, the wild grazing animals such as bison help to maintain the system by stimulating the growth of new shoots, and by leaving deposits of natural fertilizer".
But perhaps the greatest value of natural grasslands concerns genetic diversity. Our crop plants evolved from plants in natural grasslands. But while these plants have been adapted to human needs, this adaptation has been achieved at the price of loss of genetic variability. So natural grasslands are needed because they hold a 'genetic library' for the development of future crop strains.
Later in the chapter McKee enlarges on genetic diversity, not just in grasslands but other ecosystems as well. He claims that more than half of all prescription drugs are modelled on natural compounds, and about a quarter are taken directly from plants or are modified versions of plant substances. So wild plants have a vast potential for providing man with cures for many diseases.
But McKee notes that most wild species vary considerably in their genetic makeup. Not all the individuals on the species may produce the particular compound that could help to cure a disease. The implication is that we need to maintain large natural populations.
Turning to rivers and marshes, McKee observes that they are more than home to many species of plants and animals and other organisms, so their importance is not confined to the fact that a significant portion of total world biodiversity lies within them. First of all, they provide us with food. Second, they also supply water to the natural ecosystems on land which are valuable for mankind. But marshlands have been drained worldwide.
Rivers, lakes and oceans contain the organisms which transform our waste products into nutrients for the food chain. Swamps may stink, but they absorb flood waters and thus can save cities downstream from flooding. Plants round the ocean shore and in estuaries hold the land together, preventing loss of coastal land and mitigating the effects of hurricanes.
McKee turns to the complex interrelationships between species in ecosystems
In natural ecosystems, of particular importance are what are termed 'keystone species'. These are species that play a disproportionately important role in the ecosystem - "the metaphorical heart of the ecosystem". If such a species dies, then the whole ecosystem may decay and die.
Keystone species are often predators, which help to keep in check numbers of other species and maintain a balance between species. But nor all keystone species are predators. In fact the problem is that keystone species are often difficult to identity. They could be anything from a bacterium upwards. But for keystone species that can be identified, "conservation programs can gain focus and relatively quick success".
In the final, ninth chapter McKee invites us to consider the speed of human population growth and the speed of extinction of other species. In the time between when we get up in the morning and go out to work, 22,530 babies are born. Meanwhile, 9,418 people die. So there is a net gain of 13,112 people in such a short time. But this same short time also sees the end of at least one entire species. And, McKee asserts, the gain in the number of people and the loss of other species are related.
Looking ahead, there are two main things we must do to ensure the long-term sustainability of both the human population and biodiversity. One is active conservation of the natural world; the other is to practice human population control.
As far as conservation is concerned, he divides possible measures into 'simple' and 'complex'. Simple measures include things like turning down the thermostat in winter. Complex measures are more problematical. We still have insufficient understanding of how ecosystems work, despite considerable progress made. This makes conservation difficult. Consequently, while some past conservation efforts have succeeded, others have failed. Hopefully we are learning from our mistakes, but time is not on our side. And if we can instill an understanding of the values of biodiversity in the minds of people, this might lead to more urgent conservation action.
McKee considers however, that the "most effective conservation tactic we have" is to extend family planning. But we have to consider "...social freedom of choice. We cannot take away someone's right to have many children". And he goes on "And that brings us back to Garrett Hardin's tragedy of the commons: freedom in the commons brings ruin to all. Can we afford reproductive freedom, or should we impose a limit? A limit of one child per couple was imposed by China, and since abandoned. Dare we repeat the mistake?".
Actually it is not entirely clear what McKee thinks was the mistake, imposing the limit or abandoning it, but I suspect the former.
McKee notes that Hardin thought the answer was "mutual coercion, mutually agreed upon", but he thinks this is difficult to achieve. Nevertheless he does think that "we can craft subtle coercion" and he writes of using appropriate tax breaks.
Criticism
I have the following critical observations to make about this book.
By looking at biodiversity from many different angles, McKee enables non-specialists to understand both the nature of biodiversity, and the nature of the threats to that Biodiversity. He manages to avoid oversimplifying what is a very complex subject and brings out clearly the various interactions between the various processes operating within and upon ecosystems.
This is no dry-as-dust academic book. Rather it is full of interesting examples at local levels which challenge the reader to think through mechanisms of biodiversity change. Here is an example.
If you go to Beijing one notices two things. First, "an almost deafening buzz, loud enough to nearly drown out the din of constantly ringing bicycle bells". Where does the noise come from? It comes from cicadas in the trees, cicadas that far outnumber people. Second, "the lack of birds in the air". Why are there so many cicadas, and why are there no birds? The two phenomena are related.
McKee explains it this way. In the 1950s, the Chinese government realised the crisis cause by population growth, as the ability of people to feed themselves was diminishing. Later they would adopt the one child policy. But at the time they decided on another solution: Sparrows were eating people's grain, out competing people. So they had to go.
The citizens of China shot them, destroyed their eggs and nests and went out everyday to bang pots and pans "to scare away the birds when they tried to land; eventually the birds died of exhaustion and starvation".
However, birds do not just eat grain. They also eat insects. In the absence of birds insect populations grew rapidly and too late the Chinese realised "the ecological devastation they had wrought by their policy of taking over nature". The large numbers of cicadas in Beijing are one consequence of this policy.
The fact that there are numerous interesting examples in the book may perhaps have contributed to what I think is one fault of the book - it is sometimes discursive. This is particularly so in chapters five and six, and as I read these chapters I felt the thread of the argument was being obscured.
While some features of human population growth are mentioned in earlier chapters, especially chapter four, it is not until chapter five that we get a full exposition of the basic demographic features of that growth. Since human population growth is a central preoccupation of the book, and is for McKee one of the main causes, perhaps the main cause of biodiversity decline, it would have been better if it had been dealt with fully near the beginning.
Turning to the relationship between population growth and the development of agriculture (chapter four), the agricultural revolution increased food supply. But was it increased rate of population growth that caused the development of agriculture and the resultant increase in food supply, or was the causal relationship the other way round? McKee calls this the classic chicken and egg conundrum - which came first. McKee's conclusion, as I wrote earlier, is that during the period when agriculture first developed, increased rate of population growth was not caused by the development of agriculture, it took place simply because of the inherent nature of exponential growth:
He writes in relation to the graph of human population growth “I've seen similar graphs from archaeologists who use what little evidence we have to show that the human population grew after the origins of agriculture. Indeed it did! But the point is this: it did not grow because of agriculture but grew anyway, in some respects despite agriculture. There were more humans because there were more humans making more humans - that is simply the nature of population growth, even at the slow rate of 0.02033 percent per year. It is simply the product of more and more people having children, and reaching a critical mass that had not been reached in earlier interglacial ages” (my italics).
But a little later he also writes "What ensued was a positive feedback loop, or autocatalytic process: population growth spurred the origins of agriculture; agriculture fuelled population growth".
One is left rather in the air. But more fundamentally, McKee seems to confuse mechanism with cause. The mechanism of this exponential growth is as McKee explains - "there were more humans because there were more humans making more humans", like a bank account with fixed-rate compound interest. But there has to be a cause of the exponential growth. And in animal populations, the cause of exponential growth is an unlimited food supply. And McKee himself acknowledges "it is true that without agriculture the population may have stopped growing. There were simply not enough resources on earth to allow foraging populations to conti