Environmental Problems in Perspective
Broadcast ABC Radio National                
6 November  2005 

Duncan Brown 

Every animal species has functional characteristics, behavioural as well as physiological, which contribute to its identification as a species. As well as unique manual dexterity, there are two behavioural characteristics of homo sapiens that, in my opinion, have underpinned just about every impact we have had, and are having, on the planet’s ecology and general environment. The first is a remarkable ability to focus on details while overlooking or not understanding the functioning of complex dynamic systems, or what Paul Keating called ‘the big picture’. This detailed focus lies at the heart of the extraordinary achievements in virtually all fields of science and technology, but it can have its problems in an ecological context.

The second human characteristic is a widespread tendency to accept conventional wisdoms, be they religious, economic or scientific. History is studded with examples of the penalties imposed on those with unorthodox opinions, such as suggesting that the earth is round and, as well as rotating on its own axis, might actually circle the sun.

In this talk I shall try to put the environmental problems that we face into some sort of perspective. Serious environmental problems are widely acknowledged. They are mostly identified as specific challenges, such as deforestation, soil and water degradation, loss of biodiversity, and of course, global warming. The essence of my argument is that all of these challenges, while very serious, are actually symptoms of a much more dangerous predicament, a human population that is too large and too dependent on technology to be sustainable.

But let me begin with some comments on global warming, the symptom that currently seems to receive most attention and is discussed almost entirely in the context of the ‘greenhouse effect’. This is an interesting example of widespread acceptance of a conventional wisdom while other more significant factors are largely overlooked or ignored.

To simplify: the earth’s average atmospheric temperature is estimated to have risen by about 0.6 degrees Celsius over the past century. This heating is attributed predominantly to absorption by carbon dioxide of infrared radiation. The current average atmospheric concentration of carbon dioxide is estimated to be 372 parts per million, thought to be the highest for at least 420,000 years. But water also absorbs infrared radiation, and there is much more of that in the atmosphere than there is of carbon dioxide.

Many factors have contributed to heating the atmosphere since the advent of agriculture. They include major changes to the earth’s surface, especially deforestation with its associated loss of cooling by ‘evapotranspiration’; the growth of cities, which are recognised as ‘urban heat islands’; an increase in the total biomass of mammals; and most significantly, the heat produced by enormous increases in rates of combustion.

The quantity of so-called ‘fossil’ carbon burnt in 2003 amounted to some 6 Giga tonnes. Fossil carbon occurs in a wide range of substances which are not identified in that statistic; but to oversimplify and assume for example that it was distributed equally among anthracite coal and three significant components of motor fuel: pentane, hexane and decane, the heat produced amounted to 74 billion Giga calories for the year. Ignoring a range of atmospheric variables which are virtually impossible to quantify, that amount of heat has the capacity to raise atmospheric temperature by 0.06 degrees Celsius annually. Variables or not, that would seem to be enough to make a very substantial contribution to an increase of 0.6 degrees Celsius over a century. And that takes no account of other significant types of combustion, such as bushfires.

One of the curious aspects of the overwhelming focus on carbon dioxide and the ‘greenhouse effect’ is that it attributes the heating process entirely to radiation and ignores direct heating by contact and conduction. Of course primary solar heating occurs by radiation and heat is lost from the planet by radiation. But much, and indeed probably most of the heat transfer within the planet’s boundaries involves conduction. Carbon dioxide at its present concentration is irrelevant to direct heating of the atmosphere in that way.

The focus on greenhouse gases would not matter at a practical level if it led to a reduction in overall combustion. But if it provokes chemical binding of carbon dioxide, or its geosequestration, which amounts to burying it underground, or the use of alternative fuels such as hydrogen, the primary heating problem will not be addressed and there will certainly be a range of disturbing, unintended consequences.

If global warming and the other challenges mentioned earlier are symptoms, what is the primary cause of our environmental predicament? It began 10,000 years ago with the advent of agriculture. Before farming, the human biomass, like that of any other animal species, was ultimately limited by the rate of food production, basically of green plants. In other words, the relation between the human population and its food supply was one of negative feedback. What is negative feedback? A simple example is the process that regulates the temperature of a thermostatically controlled oven. When the temperature reaches the preset limit, the input of energy is either reduced or cut off.

With agriculture, that relation changed to positive feedback. That is to say when the population reached the limit of what could be supported by existing rates of food production, the response was to produce more food. In my bok, ‘Feed or Feedback’ I have proposed nine ‘Laws of Ecological Bloody-mindedness’, the second of which says, ‘Any system in a state of positive feedback will destroy itself unless a limit is placed on the flow of energy through that system’. To revert to the previous comparison, it does not take much imagination to recognise what would happen if the hotter the oven became, the more heat was applied to it.

In a social context, systems in a state of positive feedback are usually called ‘vicious circles’. They are typified by communal relations, such as war and vendettas, by drug addictions, by building freeways and parking lots to deal with traffic congestion.

Agriculture however, produced a range of side effects with their own vicious circles. With practice and experience, farming techniques improved and the farm surplus increased. This enabled or obliged some of the population to go somewhere else, and do something else for a living. That something else included making tools, some of which further increased the farm surplus and generated another vicious circle. It also led to the genesis and growth of cities, a process with a wide range of unintended consequences. Those consequences included severe deterioration of hygiene and public health, leading to increases in death rates and a substantial fall in population, especially in urban Europe. Dealing with these problems included, among other things, sewers, which in turn had their own unintended consequences.

Improvements in urban sanitation eventually led to a resumption of population growth, one results of which was an increase in the area of farmland. Food now had to be transported over greater distances from farms to cities. That, together with the development of sewers, meant that food wastes and human excrement, which formerly had been returned to farmland, were no longer recycled but, for the most part, at least in the case of sewage, were discharged ultimately into the sea. As a result, some essential nutrient elements came to be used in a way that was, and is, irreversible. The most vulnerable of these elements is phosphorus, reserves of which, allowing for the inevitable uncertainties, will probably last somewhere between 85 and 190 years.

Responses to this type of problem, and indeed to most environmental challenges, all too often amount to treating the symptoms, usually by invoking technology. Some years ago, after mentioning the phosphorus situation in a talk to engineers, I was asked if a substitute for phosphorus was available. The problem there is that the element whose chemical properties are closest to those of phosphorus is arsenic. More recently, a physicist commented that if we could develop hydrogen fusion, there would be no problem in meeting the energy requirements of recovering phosphorus from the sea. Such arguments take little or no account of the dynamics of these processes. The concentration of phosphorus in the sea is such that, to meet current rates of fertiliser application, sea water would have to be processed at a daily rate of 646 cubic kilometres. That is more than 50 times the global rate of consumption of fresh water. Not only would it require enormous amounts of energy, it would effectively destroy the marine ecosystems.

The present global human population has passed 6 billion. It is expected to reach about 9 billion by mid-century. But let us look briefly at some of the basic implications of sustaining 6 billion people. The environmental impact of any population of animals is fundamentally a result of the combined effects of many different types of process operating at different rates. All of those rates are functions of the number of individuals. Citing rates in isolation cannot lead to any firm conclusions, but it can give some feeling for the dimensions of a problem. For example, if a human population of 6 billion eats on average, 50 grammes of protein per capita daily, that amounts to a total of 208 tonnes a minute. If it were all eaten as steak the total rate of consumption would be 1040 tonnes a minute. If it were all wheat, the gross rate would be 2080 a minute. Production of food at such rates makes huge demands on a range of factors, including fertilisers and energy, the latter both in producing the food and transporting it to where it is eaten.

The basic problem of feeding a large and growing population is widely recognised, but not usually in the way I have just mentioned. A question commonly asked however is How are we to feed a population x billion? The answer usually expected is, Another Green Revolution. Recent statistics shed some light on that approach. Over a 40 year period, global grain production increased almost threefold, from 631 million tons in 1950 to 1780 million tons in 1990. But in the later stages of that period and beyond, production per capita decreased progressively from 356 kilograms in 1984 t5o 308 kilograms in 2000.

The most fundamental environmental problem, however, is a progressive simplification of the global ecosystems. In other words, we are destroying our own habitat. If that should lead to human extinction, which is possible, it would be an impressive achievement. Over the ages, many species have become extinct for various reasons, including human activities. For a species to bring out its own extinction by its own deliberate activities would be a world first and would have the essential ingredients of a particularly diabolical joke. We need to acknowledge our biology. We are a species of animal, which despite our sophistication and technological achievements, depends for survival on the same fundamental principles as all other species. Economics and technological sophistication can affect the quantitative details of that dependence, but not the basic principle.

Duncan Brown
Emeritus Professor
Department of Biological Sciences
University of Wollongong 


Publications:
Feed or Feedback
Author: Duncan Brown
Publisher: International Books
 

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