Human Social Metabolism

The focus of this workshop was the immense impact of human activities on the global environment. This impact is driven by the emergence over the past two centuries of urban industrial society, powered by fossil fuel derived energy sources. The unprecedented scale of this planetary change was the core issue of the workshop, which used the metaphor of metabolism at the scale of an organism to describe changes at the scale of civilization. For example, cities acquire materials, energy, people, and ideas as an input to produce heat, waste material flows, products, and new ideas all while interacting with other urban centers. Also considered was how this “urban metabolism” can be viewed as a fundamental topic of global change research and the implications of this metaphor for sustainability planning.

keywords: urban ecology, industrial ecology, energy, global change, population

Disciplines:
Archeology, economics, sociology, urban planning, atmospheric chemistry, climatology, and geochemistry
Overview & Relevance:
We live in a world where human activities are having an immense impact on the global environment. This impact is driven by the emergence over the past two centuries of urban industrial society based on fossil fuels. Human activities are now driving global change in ways that are both unprecedented and potentially destructive. In this workshop we were concerned primarily with the manner in which human activities affect and are affected by global environmental change. For this we begin with a metaphor, then discussed a series of issues, including the problems of scale, metabolic processes themselves, our organization of information, and observations about sociopolitical systems and the policy implications of some of our understandings about global change.
Content:
I. The Metabolic Metaphor

To gain a better understanding of this human dimension of global environmental change, we explored the use of the metabolic metaphor. We conceived of human activities under the broad rubric of human social metabolism. Human social systems can be viewed as living systems. They take in resources, energy and people, transform these into a distinctive quality of life and emit wastes, energy, people, and products. There are both advantages and disadvantages of this use of the metaphor, and it is important at the out set to recognize both.
The advantages of the metaphor are two. One derives from the fact that living systems are driven by metabolic processes, which can be seen to vary in their health or vigor. That is, the metaphor implies some variance in the health or efficiency of the metabolic process. Societies at the same level of wealth or energy consumption can vary greatly in the quality of life they give to their people. It needs little documentation to recognize, for example, that some human systems produce a high quality of life for many with relatively little energy and waste, while others use massive amounts of energy and produce immense wastes while giving their people a relatively low quality of life. It is generally accepted that eastern Europe and Russia represent the latter, where the advance of urban industrial society over the past half century has used great amount of energy, produced massive and highly toxic wastes, and has given their burgeoning populations relatively low levels of living. In many more developed countries, on the other hand, we have seen an increase in energy efficiency, a rising quality of life, and n increase in effective waste treatment. Viewing metabolic systems as varying in health or vigor gives us an important set of scientific and policy questions to ask. If we can better understand how metabolic processes work, and what drives them to become more or less efficient or healthy, we may be able to design policies and patterns of living that can increase metabolic efficiency and thus to aid in producing a sustainable human society.
In addition, the use of the metabolic metaphor leads us towards a more interdisciplinary science. Any living system is immensely complex and cannot be treated in full by any of the scientific disciplines that have emerged over the past two centuries. The promotion of interdisciplinary science is necessary because all disciplines have important limitations built into them, which are in fact a product of their great strengths. Disciplined develop great powers of observation and analysis, with both refines theories and research tools emerging out of the deep pursuit of specific knowledge. Disciplines also necessarily develop important political capacities, since they must mobilize resources for their pursuit of knowledge. Specific theories, specialized research tools, and political characteristics lead disciplines to neglect or be blind to conditions outside of their immediate purview. They create conceptual, technical, and political walls that separate them from other disciplines and this also render them incapable of seeing how an entire living system works.
The advance of global environmental science today requires some opening of disciplinary walls. This does not imply the destruction of disciplines, but it does imply that they must develop capacities to talk with one another and to work with one another. Our disciplines develop powerful tools for observation, and it is natural that those tools will at times define the operation and outcome of an entire living system, thus permitting the problem, rather than the tools of observation, to drive the enquiry.
There are also disadvantages, however, in using the metabolic metaphor. These derive primarily from the distinctive quality of human life and the immense variability of human social systems. All living organisms have identifiable techniques for absorbing and using energy, and for eliminating wastes. Individual organisms are also arranged into collectives or populations in identifiable ways. For most species, however, these technologies and forms of organization are genetically programmed and built directly into the chemical structure of the organism. For humans, what is genetically programmed is also an immense capacity for a variety in both technology and collective organization. While many conditions account for this variability (such as upright posture, a large and highly convoluted brain, bifocal vision, etc.), probably the most important is the human capacity for symbolic communication.
All of this implies that the metabolic metaphor should be used as no more than that, a metaphor. It should not be used as a procrustean bed in which we attempt to find direct and exact analogues for such things as enzymes, or chemical changes, diffusions and transformation. We do not find in biological or medical perspectives on metabolic processes, for example, such things as the racial, ethnic, linguistic, or religious identities that are powerful determinants of human actions. These are important limitations of the metabolic metaphor that must be born in mind as we attempt to use it for the enlightenment that it can provide.
II. Scale

We have had observations at the level of individual cities and below. Jean Bogener has focused on small units, individual landfills to examine the chemical processes by which methane and carbon dioxide are produced and by which they migrate. Masa Tani focused on one city, Tuscon, showing how garbage, or wastes, can tell us about life cycles and their changes. Toshiko Akayama and Toshio Kuroda have focused on one city, Tokyo, observing the material balance of the city and the movement of people in and out, with the implications for reproduction, age structures and migration. Bill Emery also showed how remote sensing can be used to distinguish urban land use and to throw some light on what are called urban heat islands.
At the level of countries or ecological regions, such as the Pacific Northwest or the Florida everglades, Dr. Way and Jackie Ott have shown how remote sensing and geographic information systems can help us both to see more and to understand better what we are seeing. Jeff Luvall examines tropical rainforest ecosystems to understand their thermal dynamics. In the process he developed a important new measure, the thermal response number, which can indicate levels of efficiency of energy use. Bob Harris examined relative weights of landfill sources of methane emission in different states. Bob Schuhman used remote sensing to examine a distinctive pattern of sea ice formation in the Greenland Sea.

We have many observations at the level of nation states. Jean Bogner has used (OECD) state level comparisons to show that refuse generation is a function of both population size and affluence. Barbara Torrey and Gayl Ness have shown how nations can differ in basic demographic dynamics, especially in reproductive regimes, and in the policy changed that have emerged to confront rapid population growth. Rosamond Naylor has shown how nations differ in rates of primary production. Bob Harris examined methane emissions levels and sources for the entire US, and Serena Schwartz used Iceland as a case of marginal existence to assess the impact of historic climate changes (the little ice age) on human behavior.

Nation states can be aggregated into world regions, with important differences in the first and third worlds in the speed, magnitude and timing of urbanization and population growth (Torrey, Ness and Fox) and agricultural output (Naylor). Jozef Pacyna, Bob Harris, and Bill Chameides all examined forms of industrial and human wastes arising largely from industrial countries.

Finally, world regions and nations can also be aggregated to the global level, where we have had important observations on waste generation, population growth, agricultural output, and industrial pollution (Bogner, Chameides, Fox, Harris, Naylor, Ness, Pacyna, Torrey).

We have also had observations for which the scale of analysis has not been specified. Bill Drake discussed transitions and Bob Marans examined the quality of life, which here emerge as issued that can be applied at any scale. Bill Emery and Bob Schuhman showed how various forms of remote sensing can be used to examine environmental changes associated with human activities.

By way of general observation, we can say that as we scale up we lose variables, and as we scale down we increase the variables being observed. We can also identify two other findings, one on scale and policy, the other on managing problems of scale.

Bob Harris observed that often environmental problems that appear massive and unmanageable at the global or even national level, appear far more manageable at the more local level. One of our major problems lies in linking scales of analysis. This is something to which more attention must me turned if we are to understand how the metabolism of, for example, a city or a nation, affects and is affected by the entire human metabolic process.

III. Metabolic processes and outcomes

A general theme can be identified, which emerged in the discussion of many of the processes. The human species has been immensely effective in carving out a niche for itself on the planet. But these very successes produce great environmental and social stresses. The successes may therefore not be sustainable.
A. Primary Production
We have been highly successful, especially over the past half century in increasing agricultural output at rates substantially above rates of population growth. Food supplies at the global and most lower levels have increased rapidly and prices have fallen. For the world as a whole, and for many societies, even in the less developed countries, obtaining sufficient food is no longer the single most important part of daily activities. Indonesia, for example, has steadily reduced the proportion of people living below the poverty level in both rural and urban areas. This has come as increases in food output have become driven less by increases in agricultural area, which was the case until about 1950, and are now driven primarily by yield increases. But Ros Naylor has shown that these yield increases may have critical limits, and that future increase may demand costs too high to be sustainable. Jackie Ott has also shown that great increases in timber production in the Pacific Northwest have come at the cost of a level of deforestation that is not sustainable, and is arrested only by national policy that can clearly protect forests.
B. Population Dynamics
Barbara Torrey, Gayl Ness, and Bob Fox have shown that the growth of urban industrial society has brought great reductions in mortality and consequent increases in human population. They have also shown that fertility declines have come in many societies, at times far more rapidly than previously considered possible. These have constituted effective adjustments to rapid population growth. The adjustments have come at both individual and collective levels, as individual families have reduced their fertility, and nations have adopted effective policies to reduce fertility through the diffusion of the new contraceptive technology.

But both Fox and Torrey have reminded us, however, that even with fertility reductions, there is a massive demographic momentum set in motion by mortality reductions. Regardless of the declining rate of population growth, we shall continue to have large and totally unprecedented increases in the sheer number of people. We shall also have great increases in the levels of resource consumption, and both of these raise frightening specter of unsustainable levels of people on earth.
C. Energy and Waste
Both Jean Bogner and Masa Tani have noted that human populations produce massive amounts of waste. These have come to be fairly well managed in many parts of the world, especially in landfills, but they still have major environmental impacts and both local and global levels. In examining the basic chemical processes by which wastes are broken down, Jean Bogner notes that landfills are now possible the major source of US Methane emission, which is a critical source of potential increases in global temperature through the greenhouse phenomenon. Methane has also experiences some successful management through policies that protect landfills to prevent the migration of methane to potentially explosive locations, and policies to extract methane for productive uses. These are growing and are successful, but they do not capture all methane, and even when they do, the combustion of methane increases the emission of carbon dioxide.

Bob Harris strikes a more optimistic note, even suggesting it is possible to have a high quality of life in a global sustainable society of 10 billion. This comes in large part from recognizing that human wastes can also be important resources. He argues for methane exploitation, and the greater use of natural gas to build a bridge to the use of some thing like a more hydrogen energy base.

Both Jozef Pacyna and Bill Chameides call attention to the more toxic wastes produced by urban industrial society. Traces of extensive heavy metal depositions can be found even in pristine artic environments. And the tropospheric ozone produced by combustion is growing and has negative impacts on human health and agricultural production.
D. Outcome: the quality of life
All discussion either explicitly or implicitly acknowledge the increase in the quality of life of large numbers and proportions of the burgeoning population. Bob Marans is part of a growing body of social scientists who attempt to measure and model the quality of life. It is known to have both objective and subjective dimensions. While much progress has been achieved in measuring and modelling this quality, it is recognized that this is only a beginning, that much more work needs to be done, and that there may be important limits to both objective and subjective levels of this quality. Objective indicators include such things as mortality and morbidity measures, which have shown a general downward trend in the world as a whole, but now show increases in come especially heavily polluted urban environments. There is also a rise in education and information distribution, which also contributed to the stock of human capital.
E. Transitions
Bill Drake has drawn a number of transition in human social metabolism under one conceptual framework. The demographic transition provides a model of movement from slow population growth through a transition of rapid growth, to a new semi equilibrium state of slow growth. We can see something of the same transition in urbanization, agricultural output, toxic production, deforestation, and other land use changes. This raises a series of questions about the causes and consequences of the speed and simultaneity of such transition. It can be hypothesized that rapid transitions, and the simultaneous occurrence of many transitions, increases the stress on a social system and may reduce the capacity to respond in productive ways to the transitions. Drake also provided data from an Indonesian study with counter intuitive findings. These showed that villages in transition experienced greater human stress and lower life qualities than did villages before or after the transition. These findings support the proposition that the transition itself is a period of considerable stress in the human social metabolic process.
IV. Scientific Tools: new instruments for seeing, organizing observations and generating action

There is a major technological breakthrough in our generation in electronic remote sensing and in the plethora of sensitive instruments to measure environmental conditions. Chemical compositions, weight, distance, and humidity can now all be measured ad analyzed with high precision. Some of these tools have led to startling new knowledge, as a variety of instruments identified ozone depletion as an unprecedented impact of urban industrial society. Others, such as report sensing and geographic information systems offer new ways to bring the social and natural science into closer interaction, and even presage a major revolution in the social sciences. Together these instruments have given us the capacity to see our planet as a single, complex, dynamic system.

Bill emery, Jackie Ott and Bob Schuhman exposed some of the powers of remote sensing, but also noted its limitations. Remote sensing can view very large areas with a wide variety of electromagnetic wavelengths and can repeat observations with regular frequencies and short intervals. This permits identification of a wide variety of land uses, and even the observation of things that are unseen by human eyes alone. New developments in synthetic aperture radar permits observations independent of reflected energy (i.e. at night and through clouds), where resolution is also independent of distance. Remote sensing cannot do everything, however. It requires ground observation for validation and interpretation, and cannot distinguish most individual elements or provide budgets of the earth’s surface. It is a powerful tool, but must be used together with extensive direct observation of whatever is being studied.

We can now portray information in both pictorial and statistical form, and we have as yet little understanding of how the two forms play upon the generation of the knowledge and understanding.

Jeff Luvall has used remote thermal sensing to develop a new measure, the thermal response number, which can help us understand how natural ecosystems work. It may also be possible to use the measure to asses the efficiency of natural and human metabolic systems.

Doug Way and Bill Emery began to expose the powers of Geographic Information Systems (GIS) both to organize our observations and data, and to develop questions and new patterns of analysis from this tool of data organization. Data from small, local levels can be entered into a geographically referenced database, permitting aggregation at higher levels and pictorial representation of a number of conditions simultaneously. More important, a GIS allows data relations to be queried in ways that are impossible or impractical without a GIS. For example we can ask about the density of an activity within specific distances, or in distinctive areal configurations, which could not be seen by statistical representations alone.

The electronic, digital character of remote sensing tools opens possibilities for knowledge generation in ways that are only beginning to be understood. Digital data from remote sensing can be integrated into a GIS, providing both statistical and pictorial representations of areal distributions. Science has far more often worked with statistical representations, but both can advance understanding though we know little about the relationship between such representations and human understanding. We can now directly see such things as urban land use expansion, desert movements, or deforestation, as well as produce accurate detailed statistics on such land use changes. In cases such as crop stressed, we can also sometimes observe conditions through electronic sensing before they are visible to the human eye on ground.

Serena Schwartz shows how interdisciplinary modelling of interactive processes can help advance understanding of the relationships between human populations and climate change. She also takes us further back in history than is common in global environmental change analysis, to examine Icelandic society coming out of the Little Ice Age.

Bob Fox has shown how computerization makes it possible to render GIS and remotely sensed data in dramatic graphic form, which can capture the attention of both individual and political decision-makers. This makes it possible to provide new and sometimes effective tool to turn scientific observations of global environmental change into policies aimed at mitigating destructive change and enhancing the more productive or sustainable changes.

We have all recognized both the difficulties and the benefits to be gained from increasing communication and collaboration between the social and natural sciences. Richard Rockwell identified some of the sources of the difficulties and suggested remedies. The social sciences often fail to undertake basic systematic measurement of the subjects they study. Theoretical and conceptual developments often appear more important, and are usually accorded greater value in academic advancement. Thus there is little systematic cumulative knowledge that social scientists can provide to natural scientists. To provide or more effective collaboration, social scientists must pay greater measurement, and especially to the geographic referencing of observations. They should also work to build more cumulative data bases to track changes in human behavior.

V. Socio-Political Systems and Policy Implications

Although we did not directly consider public policy and the socio-political systems that drive policy, many of our observations drew attention to political systems and environmentally relevant policies.

1. Population policy in the less developed countries has undergone revolutionary changes, from pro to antinatalism, in the past four decades. These changes have often been necessary for rapid fertility decline. As important have been policies toward women in particular, and toward social services in general. When women are accorded more importance in both societal arrangements and in public policy, fertility declines can come more rapidly than when they are more neglected or subjugated. Moreover, when a government develops effective local level social services, especially primary education and primary health care, fertility reduction can come more quickly than when such services are neglected. These are also policies and social arrangements that affect the quality of life in general.

On the other hand, population policies to address migration have not been effective, and have often been themselves oppressive. Migration policies, or practices towards migrants, have often sprung from deep seated ethnic identities and have been associated with extensive human violence. This is especially important, since rapid growth of numbers of people, and the great income disparities that exist between different part of the world signal great increases in migratory pressures in the near future. Moreover, migratory pressured often bring about violent confrontations based on ethnic or racial identities.
2. Waste management policies in developed counties have been effective in controlling the migration and explosion of methane, and also in encouraging the extraction of methane for productive purposes.
3. Energy policies can be designed to promote production or to promote conservation and the development of alternative environmentally more benign sources of energy.
4. Policies to reduce tropospheric ozone appear to have been fully ineffective. One suggestion is that this is due to the focus on VOC rather than on the NOX components of ozone creation.
5. Agricultural policies can promote increases in food production. Of special importance are support for research and development, for agricultural extension, and for production, especially in the third world.
6. While we are wary of uncritical liberal biases, there seems to be mounting evidence that open social and political systems, which permit or encourage difference and change, and which accord human dignity to broader ranges of people may offer greater possibilities for adaptive innovations than systems that are oppressive.