The Party's Over Part 1

The Party's Over.

Oil, War and the Fate of Industrial Societies.

Richard Heinberg.

Acknowledgments.

I am deeply indebted to three geologists who read parts of the ma.n.u.script and offered invaluable corrections, additions, and advice: C. J. Campbell, who read the entire ma.n.u.script and offered editorial as well as technical suggestions; Jean Laherrere, who read Chapter 3 and offered detailed criticisms and suggestions; and Walter Youngquist, who read an early version of Chapter 3 and supplied helpful resource materials.

I am also indebted to Ron Swenson, an expert on renewable energies, who offered immensely valuable insights and suggestions for Chapter 4.

For the past several years my students at New College of California have heard me develop the ideas for this book in lectures; during the same period my colleagues on staff and faculty have engaged me in frequent conversations about issues related to the book. I would like to thank all of these wonderful people, both for their comments and for their patience with me as I doggedly pursued this topic.

Readers of my monthly MuseLetter read early drafts of chapters and also offered helpful suggestions. I thank them for their loyalty and interest.

Thanks to Chris Plant and the rest of the staff at New Society Publishers for taking on a controversial topic.

I must mention my debt of grat.i.tude to Jay Hanson, whose research and doc.u.mentation of this topic on his web site provided much of the original inspiration for this book.

For their kind permission to quote from their work, my appreciation goes out to Michael C. Lynch, Bjrn Lomborg, C. J. Campbell, and Richard C. Duncan.

Finally, I would like to thank my wife, Janet Barocco, for her constant support and encouragement.

Introduction.

The skylines lit up at dead of night, the air-conditioning systems cooling empty hotels in the desert, and artificial light in the middle of the day all have something both demented and admirable about them: the mindless luxury of a rich civilization, and yet of a civilization perhaps as scared to see the lights go out as was the hunter in his primitive night.

- Jean Baudrillard (1989).

It is evident that the fortunes of the world's human population, for better or for worse, are inextricably interrelated with the use that is made of energy resources.

- M. King Hubbert (1969).

There is no subst.i.tute for energy. The whole edifice of modern society is built upon it .... It is not "just another commodity" but the precondition of all commodities, a basic factor equal with air, water, and earth.

- E. F. Schumacher (1973).

The world is changing before our eyes - dramatically, inevitably, and irreversibly. The change we are seeing is affecting more people, and more profoundly, than any that human beings have ever witnessed. I am not referring to a war or terrorist incident, a stock market crash, or global warming, but to a more fundamental reality that is driving terrorism, war, economic swings, climate change, and more: the discovery and exhaustion of fossil energy resources.

The core message of this book is that industrial civilization is based on the consumption of energy resources that are inherently limited in quant.i.ty, and that are about to become scarce. When they do, compet.i.tion for what remains will trigger dramatic economic and geopolitical events; in the end, it may be impossible for even a single nation to sustain industrialism as we have known it during the twentieth century.

What comes after industrialism? It could be a world of lower consumption, lower population, and reduced stress on ecosystems. But the process of getting there from here will not be easy, even if the world's leaders adopt intelligent and cooperative strategies - which they have so far shown little willingness to do. Nevertheless, the end of industrial civilization need not be the end of the world.

This is a message with such vast implications - and one that so contradicts the rea.s.surances we receive daily from politicians and other cultural authorities - that it appears, on first hearing, to be absurd. However, in the chapters that follow I hope to show * the complete and utter dependency of modern industrial societies on fossil fuel energy resources as well as the inability of alternatives to fully subst.i.tute for the concentrated, convenient energy source that fossil fuels provide; * the vulnerability of industrial societies to economic and political disruption as a result of even minor reductions in energy resource availability; * the inevitability of fossil fuel depletion; * the immediacy of a peak in fossil fuel production, meaning that soon less will be available with each pa.s.sing year regardless of how many wild lands are explored or how many wells are drilled; * the role of oil in US foreign policy, terrorism and war, and the geopolitics of the 21st century; * and hence the necessity of our responding to the coming oil production peak cooperatively, with compa.s.sion and intelligence, in a way that minimizes human suffering over the short term and, over the long term, enabling future generations to develop sustainable, materially modest societies that affirm the highest and best qualities of human nature.

I came to the subject of energy resources out of a pa.s.sion for ecology and a decades-long effort to understand what makes human cultures change - an attempt, that is, to answer the question, What causes one group of people to live in air-conditioned skysc.r.a.pers and shop at supermarkets, while another genetically similar group lives in bark huts and gathers wild foods?

This is a complex problem. There is no single explanation for the process of cultural change; reasons vary considerably from situation to situation. However, as many students of the subject eventually conclude, there is one element in the process that is surprisingly consistent - and that is the role of energy.

Life itself requires energy. Food is stored energy. Ecosystems organize themselves to use energy as efficiently as possible. And human societies expand or contract, invent new technologies or remain static, in response to available energy supplies. Pay attention to energy, and you can go a long way toward understanding both ecological systems and human social systems, including many of the complexities of economic and political history.

Once I realized this, I began to focus my attention on our society's current energy situation. Clearly, over the past century or so we have created a way of life based on mining and consuming fossil energy resources in vast and increasing quant.i.ties. Our food and transportation systems have become utterly dependent on growing supplies of oil, natural gas, and coal. Control of those supplies can therefore determine the economic health and even the survival of nations. Then I tried to find answers to the following questions: How much petroleum is left? How much coal, natural gas, and uranium? Will we ever run out? When? What will happen when we do? How can we best prepare? Will renewable subst.i.tutes - such as wind and solar power - enable industrialism to continue in a recognizable form indefinitely?

Important questions, these. But a quick initial survey of available answers proved to be confusing and frustrating. There are at least four sets of voices spouting mutually contradictory opinions: * The loudest and most confident voice belongs to conventional free-market economists, who view energy as merely one priced commodity among many. Like other commodities, energy resources are subject to market forces: temporary shortages serve to raise prices, which in turn stimulates more production or the discovery of subst.i.tutes. Thus the more energy we use, the more we'll have! Economics n.o.bel laureate Robert Solow has gone so far as to say that, ultimately, " ... the world can, in effect, get along without natural resources."1 Economists like him have a happy, cornucopian view of our energy future. If an energy crisis appears, it will be a temporary one caused by "market imperfections" resulting from government regulation. Solutions will come from the market's natural response to price signals if those signals are not obscured by price caps and other forms of regulatory interference.

* A more strident voice issues from environmental activists, who are worried about the buildup of greenhouse gases in the atmosphere and about various forms of hydrocarbon-based pollution in air, water, and soil. For the most part, ecologists and eco-activists are relatively unconcerned with high energy prices and petroleum resource depletion - which, they a.s.sume, will occur too late to prevent serious environmental damage from global warming. Their message: Conserve and switch to renewables for the sake of the environment and our children's and grandchildren's welfare.

* A third and even more sobering collective voice belongs to an informal group of retired and independent petroleum geologists. This is a voice that is so attenuated in the public debate about energy that I was completely unaware of its existence until I began systematically to research the issues. The petroleum geologists have nothing but contempt for economists who, by reducing all resources to dollar prices, effectively obscure real and important physical distinctions. According to the petroleum geologists, this is arrant and dangerous nonsense. Petroleum will run out. Moreover, it will do so much sooner than the economists a.s.sume - and subst.i.tutes will not be easy to find. The environmentalists, who for the most part accept economists' estimates of petroleum reserves, are, according to the geologists, both right and wrong: we should indeed be switching to renewable alternatives, but because the renewables cannot fully replicate the energy characteristics of fossil fuels and because decades will be required for their full development, a Golden Age of plentiful energy from renewable sources is simply not in the cards. Society must engage in a crash program of truly radical conservation if we are to avoid economic and humanitarian catastrophe as industrialism comes to its inevitable end.

* Finally, there is the voice that really matters: that of politicians, who actually set energy policy. Most politicians tend to believe the economists because the latter's cornucopian message is the most agreeable one - after all, no politician wants to be the bearer of the awful news that our energy-guzzling way of life is waning. However, unlike economists, politicians cannot simply explain immediate or projected energy constraints away as a temporary inconvenience. They have to deal with const.i.tuents - voters - who want good news and quick solutions. When office holders are forced to acknowledge the reality of an impending energy crisis, they naturally tend to propose solutions appropriate to their const.i.tuency and their political philosophy, and they predictably tend to blame on their political opponents whatever symptoms of the crisis cannot be ignored. Those on the political Left usually favor price caps on energy and subsidies to low-income rate payers; they blame price-gouging corporations for blackouts and high prices. Those on the political Right favor "free-market" solutions (which often entail subsidies to oil companies and privately owned utilities) and say that shortages are due to environmental regulations that prevent companies from further exploration and drilling.

Personally, I have long supported the program of developing renewable energy alternatives that eco-activists advocate. I still believe in that program, now more than ever. However, after studying the data and interviewing experts, I have concluded that, of the four groups described above, the retired and independent petroleum geologists are probably giving us the most useful factual information. Theirs is a long-range view based on physical reality. But their voice is the hardest to hear because, while they have undeniable expertise, there are no powerful inst.i.tutions helping them spread their message. In this book, the reader will find the geologists' voices prominently represented.

As should be obvious from the t.i.tle of this book, I am choosing to emphasize the bad news that we are approaching the first stages of an energy crisis that will not easily be solved and that will have a profound and permanent impact on our way of life. There is also good news to be conveyed: it is possible that, in the post-petroleum world, humankind will discover a way of living that is more psychologically fulfilling as well as more ecologically sustainable than the one we have known during the industrial age. However, unless we are willing to hear and accept the bad news first, the good news may never materialize.

Many books published during the past few decades have pleaded with us to reduce our non-renewable energy usage for a variety of reasons - to lessen the greenhouse effect and environmental pollution, to halt the destruction of local communities and cultures, or to preserve human health and sanity. Though I agree with those prescriptions, this is not another such book. Until now, humankind has at least theoretically had a choice regarding the use of fossil fuels - whether to use constantly more and suffer the long-term consequences or to conserve and thus forgo immediate profits and industrial growth. The message here is that we are about to enter a new era in which, each year, less net energy will be available to humankind, regardless of our efforts or choices. The only significant choice we will have will be how to adjust to this new regime. That choice - not whether, but how to reduce energy usage and make a transition to renewable alternatives - will have profound ethical and political implications. But we will not be in a position to navigate wisely through these rapids of cultural change if we are still living with the mistaken belief that we are somehow ent.i.tled to endless energy and that, if there is suddenly less to go around, it must be because "they" (the Arabs, the Venezuelans, the Canadians, the environmentalists, the oil companies, the politicians, take your pick) are keeping it from us.

Industrial societies have been flouris.h.i.+ng for roughly 150 years now, using fossil energy resources to build far-flung trade empires, to fuel the invention of spectacular new technologies, and to fund a way of life that is opulent and fast-paced. It is as if part of the human race has been given a sudden windfall of wealth and decided to spend that wealth by throwing an extravagant party. The party has not been without its discontents or costs. From time to time, a lone voice issuing from here or there has called for the party to quiet down or cease altogether. The partiers have paid no attention. But soon the party itself will be a fading memory - not because anyone decided to heed the voice of moderation, but because the wine and food are gone and the harsh light of morning has come.

Here is a brief tour of the book's contents: Chapter 1 is a general discussion of energy in nature and human societies. In it we see just how central a role energy has played in the past and why it will shape the fates of nations in the decades ahead. This chapter is a brief guided trip through the fields of ecology, cultural anthropology, and history, with energy as our tour guide.

Chapter 2 traces the history of the industrial era - the historic interval of cheap energy - from the Europeans' first use of coal in the 12th century to the 20th-century miracles of petroleum and electricity with their cascading streams of inventions and conveniences.

Chapter 3 is in many respects the informational core of the book. In it we will learn to a.s.sess oil resources and review estimates of current reserves and extraction rates. Many readers may find the information in this chapter unfamiliar and disturbing since it conflicts with what we frequently hear from economists and politicians. Among other things, we will explore the question, Why do the petroleum-reserve estimates of independent geologists diverge so far from those of governmental agencies like the US Geological Survey?

Chapter 4 explores the available alternatives to oil: from coal and natural gas to solar power, wind, and hydrogen, including cold fusion and "fringe" free-energy devices.

Chapter 5 discusses the meaning and the implications of the approaching peak in fossil-fuel production. We will explore the connections between petroleum dependence, world food systems, and the global economy. We will also examine the global strategic compet.i.tion for dwindling petroleum resources and attempt to predict the flashpoints for possible resource wars.

Finally, Chapter 6 addresses the vital question: What can we do? - individually, as communities, as a nation, and globally. In this chapter we will explore solutions, from the simple practical steps any of us can take to policy recommendations for world leaders. As we will see, humankind now must decide whether to respond to resource shortages with bitter compet.i.tion or with a spirit of cooperation. We will face this decision at all levels of society - from the family and neighborhood to the global arena of nations and cultures.

1.

Energy, Nature and Society.

The life contest is primarily a compet.i.tion for available energy.

- Ludwig Boltzman (1886).

Other factors remaining constant, culture evolves as the amount of energy harnessed per capita per year is increased, or as the efficiency of the instrumental means of putting the energy to work is increased. We may now sketch the history of cultural development from this standpoint.

- Leslie White (1949).

[T]he ability to control energy, whether it be making wood fires or building power plants, is a prerequisite for civilization.

- Isaac Asimov (1991).

We live in a universe pulsing with energy; however, only a limited amount of that energy is available for our use. We humans have recently discovered a temporary energy subsidy in the forms of coal, oil, and natural gas, and that momentary energy bonanza has fueled the creation of modern industrial societies. We tend to take that subsidy for granted, but can no longer afford to do so. Emerging circ.u.mstances will require us to think much more clearly, critically, and contextually about energy than we have ever done before.

In this chapter we will first review some basic facts about energy and the ways in which nature and human societies function in relation to it. We will follow this discussion of principles with an exploration of the history of the United States' rise to global power, showing the central role of energy resources in that process.

The first section below includes information that may already be familiar to many readers from high-school or college courses in physics, chemistry, and biology. I begin with this material because it is absolutely essential to the understanding of all that follows throughout the book. Have patience. We will soon arrive in new (and disturbing) intellectual territory.

Energy and Earth: The Rules of the Game.

Few understand exactly what energy is. And yet we know that it exists; indeed, without it, nothing would exist.

We commonly use the word energy in at least two ways. A literary or music critic might say that a particular poem or performance has energy, meaning that it has a dynamic quality. Similarly, we might remark that a puppy or a toddler has a lot of energy. In those cases we would be using the term intuitively, impressionistically, even mystically - though not incorrectly. Physicists and engineers use the word to more practical effect. They have found ways to measure energy quite precisely in terms of ergs, watts, calories, and joules. Still, physicists have no more insight into energy's ultimate essence than do poets or philosophers. They therefore define energy not in terms of what it is, but by what it does: as "the ability to do work" or "the capacity to move or change matter." It is this quantifiable meaning of the term energy that concerns us in this book. Though we are considering something inherently elusive (we cannot, after all, hold a jar of pure energy in our hands or describe its shape or color), energy is nevertheless a demonstrable reality. Without energy, nothing happens.

In the 19th century, physicists formulated two fundamental laws of energy that appear to be true for all times and places. These are commonly known as the First and Second Laws of Thermodynamics. The first, known as the Conservation Law, states that energy cannot be created or destroyed, only transformed. However, energy is never actually "transformed" in the sense that its fundamental nature is changed. It is more accurate to think of energy as a singular reality that manifests itself in various forms - nuclear, mechanical, chemical, thermal, electromagnetic, and gravitational - which can be converted from one to another.

The Second Law of Thermodynamics states that whenever energy is converted from one form to another, at least some of it is dissipated, typically as heat. Though that dissipated energy still exists, it is now diffuse and scattered, and thus less available. If we could gather it up and re-concentrate it, it could still work for us; but the act of re-concentrating it would itself require more energy. Thus, in effect, available energy is always being lost. The Second Law is known as the law of entropy - a term coined by the German physicist Rudolf Clausius in 1868 as a measure of the amount of energy no longer practically capable of conversion into work. The Second Law tells us that the entropy within an isolated system inevitably increases over time. Since it takes work to create and maintain order within a system, the entropy law tells us that, in the battle between order and chaos, it is chaos that ultimately will win.

It is easy to think of examples of entropy. Anyone who makes the effort to keep a house clean or who tries keeping an old car repaired and on the road knows about entropy. It takes work - thus energy - to keep chaos at bay. However, it is also easy to think of examples in which order seems naturally to increase. Living things are incredibly complex, and they manage not only to maintain themselves but to produce offspring as well; technological gadgets (such as computers) are always becoming more sophisticated and capable; and human societies seem to become larger, more complex, and more powerful over time. These phenomena all appear to violate the law of entropy. The key to seeing why they actually don't lies in the study of systems.

The Second Law states that it is the entropy in an isolated system that will always increase. An isolated system is one that exchanges no energy or matter with its environment. The only truly isolated system that we know of is the universe. But there are two other possible types of energy systems: closed systems (they exchange energy with their environment, but not matter) and open systems (they exchange both energy and matter with their environment). The Earth is, for the most part, a closed system: it receives energy from the Sun and re-radiates much of that energy back out into s.p.a.ce; however, aside from the absorption of an occasional asteroid or comet fragment, the Earth exchanges comparatively little matter with its cosmic environment. Living organisms, on the other hand, are examples of open systems: they constantly receive both energy and matter from their environment, and also give off both energy and matter.

It is because living things are open systems, with energy and matter continually flowing through them, that they can afford to create and sustain order. Take away their sources of usable energy or matter, and they soon die and begin to disintegrate. This is also true of human societies and technologies: they are open systems that depend upon the flow of energy and matter to create temporary islands of order. Take away a society's energy sources, and "progress" - advances in technology and the growth of complex inst.i.tutions - quickly ceases. Living systems can increase their level of order and complexity by increasing their energy flow-through; but by doing so, they also inevitably increase the entropy within the larger system of which they are a part.

Matter is capable of storing energy through its chemical order and complexity. This stored energy can be released through chemical processes, such as combustion or, in the case of living things, digestion. Materials that store energy are called fuels.

The law of entropy holds true for matter as well as for energy. When energy is dissipated, the result is called heat death. When matter is eroded or degraded, the result is called matter chaos. In both cases, the result is a randomization that makes both matter and energy less available and useful.

In past decades, a simplistic understanding of entropy led many scientists to conclude that order is an anomaly in the universe - a belief that made it difficult to explain how biological evolution has proceeded from the simple to the complex, from bacteria to baleen whales. In recent years, more sophisticated understandings have developed, centered mostly around chaos theory and Ilya Prigogine's theory of dissipative structures. Now it is known that, even within apparently chaotic systems, deeper forms of order may lurk. However, none of these advances in the understanding of living systems and the nature of entropy circ.u.mvents the First or Second Laws of Thermodynamics. Order always has an energy cost.

Because the Earth is a closed system, its matter is subject to entropy and is thus continually being degraded. Even though the planet constantly receives energy from its environment, and even though the ecosystems within it recycle materials as efficiently as they can, useful concentrations of matter (such as metal ores) are always being dispersed and made unusable.

On Earth, nearly all the energy available to fuel life comes from the Sun. There are a very few exceptions; for example, oceanographers have discovered organisms living deep in ocean trenches, thriving on heat emanating from the Earth's core. But when we consider the energy flows that support the biosphere as a whole, sources originating within the planet itself are trivial.

The Sun continually gives off an almost unimaginable amount of energy - the equivalent of roughly 100 billion hydrogen bombs going off each second -radiating it in all directions into s.p.a.ce. The Earth, 93 million miles away, is a comparatively tiny target for that energy, receiving only an infinitesimal fraction of what our local star radiates. Still, in terms that concern us, that's plenty: our planet is constantly bathed in 1,372 watts of sunlight energy per square meter. The total influx of solar energy to the Earth is more than 10,000 times the total amount of energy humankind presently derives from fossil fuels, hydro power, and nuclear power combined. The relative vastness of this solar-energy influx as compared with society's energy needs might suggest that humans will never face a true energy shortage. But only some of this solar energy is actually available for our use: much is re-radiated into s.p.a.ce (30 percent is immediately reflected from clouds and ice), and nearly all of the rest is already doing important work, such as driving the weather by heating the atmosphere and oceans and fueling life throughout the biosphere.

Some organisms - green plants, including algae and phytoplankton - are able to take in energy directly from sunlight. Biologists call these organisms producers, or autotrophs ("self-feeders"), because they make their own food from inorganic compounds in their environments.1 Producers trap solar energy through photosynthesis, a process in which chlorophyll molecules convert sunlight into chemical energy. Most of us tend to a.s.sume that green plants are mostly made up of materials from the soil drawn up through the plants' roots. This is only partly true: plants do require minerals from the soil, but most of their ma.s.s is actually derived from air, water and sunlight, via photosynthesis. Hundreds of chemical changes are involved in this process, the results of which can be summarized as follows: Glucose - a sugar, or carbohydrate - serves as food for plants and can be converted into materials from which the plants build their tissues. Plants absorb only about half of the solar energy that falls on them; of that, they are able to convert only about one to five percent into chemical energy. Still, even at this low level of efficiency, photosynthetic organisms each year capture a little more than twice the total amount of energy used annually by human beings. (However, within the US, the total amount of energy captured in photosynthesis amounts to only about half of the energy used by humans.) All nonproducing organisms are cla.s.sifiable as consumers, or heterotrophs ("other-feeders"). By digesting glucose and other complex organic compounds that were produced through photosynthesis, consumers absorb the energy previously locked into chemical order by green plants. In the process, they produce waste - less-ordered material - which they excrete into the environment. In effect, consumers feed on order and excrete chaos in order to survive. All animals are consumers.

There are several categories of consumers: herbivores, which eat plants; carnivores, which eat other consumers (primary carnivores eat herbivores, secondary carnivores eat other carnivores, and tertiary carnivores eat carnivores that eat carnivores); scavengers, which eat dead organisms that were killed by other organisms or died naturally; detritovores, which eat cast-off fragments and wastes of living organisms; and decomposers, consisting mostly of certain kinds of bacteria and fungi, which complete the final breakdown and recycling of the remains and wastes of all organisms. Human beings - like foxes, bears, rats, pigs, and c.o.c.kroaches - are omnivores, eating both plants and animals.2 Both producers and consumers use the chemical energy stored in glucose and other organic compounds to fuel their life processes. In most cells, this is accomplished through aerobic respiration, a process with a net chemical change opposite that of photosynthesis: Some decomposers get energy through anaerobic respiration, or fermentation. Instead of carbon dioxide and water, the end products are compounds such as methane gas (a simple hydrocarbon) and ethyl alcohol. Normally, in the decay of organic materials, a chemical process based on aerobic respiration occurs, with carbon-based organic material combining with oxygen to yield carbon dioxide and water. However, if there is no additional oxygen available because of an anaerobic environment - such as exists if organic matter is buried under sediment or stagnant water - then anaerobic decomposers go to work. Plant and animal remains are transformed into hydrocarbons as oxygen atoms are removed from the carbohydrate organic matter. This is the chemical basis for the formation of fossil fuels. It is now believed that most oil comes from a few brief epochs of extreme global warming over quite short spans of geological time. The process began long ago and today yields fuels - chemically stored sunlight - that are energy-dense and highly usable.

Energy in Ecosystems: Eating and Being Eaten.

Just as individual organisms use energy, so do complex systems made up of thousands or millions of organisms. The understanding of how they do so has been one of the central projects of the science of ecology.

The term ecology was coined in 1869 by German biologist Ernst Haeckel from the Greek roots oikos ("house" or "dwelling") and logos ("word" or "study of"). However, the discipline of ecology - which is the study of how organisms interact with one another and their surroundings - did not really flourish until the beginning of the 20th century.

At first, ecologists studied food chains - big fish eating little fish. Quickly, however, they realized that since big fish die and are subsequently eaten by scavengers and microbes that are then eaten by still other organisms, it is more appropriate to speak of food cycles or webs. Further a.n.a.lysis yielded the insight that all of nature is continually engaged in the cycling and recycling of matter and energy. There are carbon cycles, nitrogen cycles, phosphorus cycles, sulfur cycles, and water cycles. Of fundamental importance, however, are energy flows - which tend to drive matter cycles and which, as we have seen, begin in nearly all cases with sunlight.

Energy is the basic currency of ecosystems, pa.s.sing from green plants to herbivores to carnivores, with decomposers partic.i.p.ating along the way. With each transfer of energy, some is lost to the environment as low-quality heat. Typically, when a caterpillar eats a leaf, when a thrush eats the caterpillar, or when a hawk eats the thrush, only 5 to 20 percent of usable energy is transferred from one level to the next. Thus, if green plants in a given area capture, for example, 10,000 units of solar energy, then roughly 1,000 units will be available to support herbivores, even if they eat all of the plants; only 100 units will be available to support primary carnivores; only 10 to support secondary carnivores; and only one to support tertiary carnivores. The more energy-transfer levels there are in the system, the greater the c.u.mulative energy losses. In every ecosystem, most of the chemically bound energy is contained among the producers, which also account for most of the bioma.s.s. The herbivores present will account for a much smaller fraction of the bioma.s.s, and the carnivores for yet a still smaller fraction. Thus the energy flow in ecosystems is typically represented by a pyramid, with producers on the bottom and tertiary carnivores at the top.

The energy available in an ecosystem is one of the most important factors in determining its carrying capacity, that is the maximum population load of any given species that is able to be supported by its environment on an ongoing basis. Energy is not the only factor, however; the operative principle in determining carrying capacity is known as Liebig's Law (after the 19th-century German scientist Justus von Liebig), which states that whatever necessity is least abundant, relative to per-capita requirements, sets the environment's limit for the population of any given species. For a plant, the limiting factor may be heat, sunlight, water, nitrogen, or phosphorus. Sometimes too much of a limiting factor restricts the carrying capacity, as when plants are killed by too much water or too much soil acidity. The limiting factor for any population may change over time. For herbivores and carnivores, the most common limiting factor is food-energy. This is why ecologists pay so much attention to food webs: when we understand the energy flows within an ecosystem, the dynamics of the system as a whole become clear.

These days the term ecology is often understood to be used merely in a scientific critique of human society's negative impact on nature. There are two reasons for this. The first is that early ecologists soon realized that, since humans are organisms, ecology should include the study of the relations.h.i.+p between people and the rest of the biosphere. The second is that, as early ecologists cataloged and monitored various natural systems, they found that it was becoming increasingly difficult to study such systems in an undisturbed state; everywhere, nature was being impacted by the human presence.

This impact itself became a focus of investigation, and soon ecologists realized that disturbed and undisturbed systems differ in clear ways. Ecosystems that have not been disturbed significantly for long periods of time (whether by humans or by natural disasters) tend to reach a state of dynamic equilibrium which ecologists call a climax phase, meaning that organisms have adapted themselves to one another in such a way as to maintain relatively constant population levels, to avoid direct compet.i.tion, to keep energy flow-through to a minimum, and to recycle available energy and nutrients as completely as possible. They have formed, to use an anthropomorphic term, a community.

Biological communities are kept in equilibrium through balancing feedback loops. A useful technological example of a balancing feedback loop is a thermostat: if a room gets too cold, the thermostat triggers the furnace to turn on; when the room achieves the set temperature, the thermostat turns the furnace off. The temperature of the room varies, but only narrowly. Similarly, feedback loops in ecosystems - such as predator-prey relations.h.i.+ps - tend to keep varying population levels within narrow ranges. If the vole population increases, fox and hawk populations will soon expand to take advantage of this food-energy surplus. The increase in the hawk and fox populations will then reduce the vole population, whose diminution will eventually lead to a reduction in the numbers of hawks and foxes as well.

The more mature the ecosystem, the more thoroughly the organisms in it use the available energy. Waste from one organism becomes food for another. Moreover, in order not to expend energy unnecessarily, organisms will tend to avoid direct compet.i.tion through any of several strategies: by dividing the habitat into niches, by specializing (for example, if two species depend upon the same food source, they may evolve to feed at different times of day), or by periodic migration. Territorial animals avoid wasting energy in fights by learning to predict one another's behavior from signals like posture, vocalizations, and scent marks.3 As a result, climax ecosystems give the appearance of cooperation and harmony among member species. The degree of mutual interdependence achieved can be astounding, with differing species relying on one another for food, shelter, transportation, warnings of danger, cleaning, or protection from predators. As biologist Lewis Thomas once put it, "The urge to form partners.h.i.+ps, to link up in collaborative arrangements, is perhaps the oldest, strongest, and most fundamental force in Nature. There are no solitary, free-living creatures, every form of life is dependent on other forms."4 In climax ecosystems, population levels are kept relatively in check not only through predators culling prey species, but also through species acting on their own to limit their numbers via internal feedback mechanisms. These internal mechanisms are seen in elephants, for example, which regulate their population densities through delays in the onset of maturity as well as among smaller animals such as mice, where females typically ovulate more slowly or cease ovulation altogether if populations become too dense. In many bird species, much of the adult population simply does not breed when there is no food-energy available to support population growth.

All of this contrasts with ecosystems that have recently been seriously disturbed, or whose balances have been upset by the arrival of a new species.

Fires, floods, and earthquakes are high-energy events that can overwhelm the energy balances of climax ecosystems. Disturbed ecosystems are characterized by disequilibrium and change. First, pioneer species appear - and proliferate wildly. They then give way to various secondary species. The environment pa.s.ses through a series of phases, known collectively as ecological succession, until it arrives again at a climax phase. During these successive phases, earlier organisms transform the environment so that conditions are favorable for organisms that appear later. For example, after a forest fire, tough, annual, weedy, ground-cover plants spring up first. During the second or third season, perennial shrubs begin to dominate; a few years later, young trees will have grown tall enough to shade out the shrubs. In some cases, this first generation of trees may eventually be replaced by other tree species that grow taller. It may take many decades or even centuries for the land to again become a climax forest ecosystem. If we accept the view that the Earth can itself be treated as a living being, as has been proposed by biologists James Lovelock and Lynn Margulis5, then it might be appropriate to think of succession as the Earth's method of healing its wounded surface.

In other instances, balances in ecosystems can be upset as a result of the appearance of exotic species. These days, the arrival of most exotic species is due to the actions of humans importing plants and animals for food, decoration, or as pets. But sometimes new arrivals appear on a freak wind current or a piece of flotsam. Most newcomers, having evolved in other environments, are unfit for life in their new surroundings and quickly perish; but occasionally, an exotic species finds itself in an environment with plenty of available food and with no predators to limit its numbers. In such instances, the species becomes an invader or colonizer and can compete directly with indigenous species. Most Americans are familiar with Scotch broom, starlings, and kudzu vine - all of which are successful, persistent, and profuse colonizers.

Many colonizing species are parasites or disease-causing organisms: bacteria, protozoa, or viruses. When such organisms initially invade a host species, they are often especially virulent because the host has not yet developed the proper antibodies to ward off infection. But the death of the host is no more in the interest of the microbe than it is in the interest of the host itself since the former is dependent on the latter for food and habitat. Thus, over time, disease organisms and their hosts typically co-evolve, so that diseases which initially were fatal eventually become relatively innocuous childhood diseases like measles, mumps, or chickenpox.

Not all feedback loops create balance, however; in reinforcing feedback loops, change in one direction causes more change in the same direction. A technological example would be a microphone held too close to the speaker of the amplifier to which it is attached. The microphone picks up sound coming from the speaker, then feeds it back to the amplifier, which amplifies the sound and sends it back through the speaker, and so on. The result is a loud, unpleasant squeal.

Colonizing species sometimes create reinforcing feedback loops within natural systems. While population levels among species in climax ecosystems are relatively balanced and stable, populations in disturbed or colonized ecosystems go through dramatic swings. When there is lots of food-energy available to the colonizing species, its population blooms. Suppose the organism in question is the rabbit, and the environment is Australia - a place previously devoid of rabbits, where there is plenty of food and no natural predator capable of restraining rabbit population growth. Each rabbit adds (on average) ten new baby rabbits to the population. This means that if we began with ten rabbits, we will soon have 110. Each of these adds ten more, and before we know it, we have 1,210 rabbits. More rabbits cause more babies, which cause more rabbits, which cause more babies.

Obviously, this cannot go on forever. The food supply for the rabbits is ultimately limited, and eventually there will be more rabbits than there is food to support them. Over the long term, a balance will be struck between rabbits and food. However, that balance may take a while to be achieved. The momentum of population increase may lead the rabbits to overshoot their carrying capacity. The likelihood of overshoot is increased by the fact that the environment's carrying capacity for rabbits is not static. Since the proliferating rabbits may eat available vegetation at a faster rate than it can naturally be regenerated, the rabbits may actually reduce their environment's rabbit-carrying capacity even as their numbers are still increasing. If this occurs, the rabbit population will not simply gradually diminish until balance is achieved; instead, it will rapidly crash - that is, the rabbits will die off.

At this point, depending on how seriously the rabbits have altered their environment's carrying capacity, they will either adapt or die out altogether. If they have not eaten available food plants to the point that those plants can no longer survive and reproduce, the rabbit population will stabilize at a lower level. For a time, population levels will undergo more seasonal swings of bloom, overshoot, and die-off as food plants recover and are again eaten back. Typically, those swings will slowly diminish as a balance is achieved and as the rabbits become incorporated into the ecosystem. This is, in fact, what has begun to happen in Australia since the introduction of rabbits by Europeans in 1859. However, if the rabbits were ever to eat food plants to the point of total elimination, they would reduce the rabbit-carrying capacity of their environment to zero. At that point, the rabbits would die out altogether.

Since successful invaders change their environments, usually overpopulating their surroundings and overshooting their ecosystem's carrying capacity, colonized ecosystems are typically characterized by reduced diversity and increased energy flow-through. As colonizers proliferate, energy that would ordinarily be intercepted by other organisms and pa.s.sed on through the food web goes unused. But this is always a temporary state of affairs: living systems don't like to see energy go to waste, and sooner or later some species will evolve or arrive on the scene to use whatever energy is available.

These are the rules of the game with regard to energy and life: energy supplies are always limited; there is no free ride. In the long run, it is in every species' interest to learn to use energy frugally. Compet.i.tion, though it certainly exists in Nature, is temporary and limited; Nature prefers stable arrangements that entail self-limitation, recycling, and cooperation. Energy subsidies (resulting from the disturbance of existing environments or the colonization of new ones) and the ensuing population blooms provide giddy moments of extravagance for some species, but crashes and die-offs usually follow. Balance eventually returns.

Social Leveraging Strategies: How to Gain an Energy Subsidy.

We don't often tend to think about the social sciences (history, economics, and politics) as subcategories of ecology. But since people are organisms, it is apparent that we must first understand the principles of ecology if we are to make sense of events in the human world.

Anthropological data confirm that humans are capable of living in balance and harmony as long-term members of climax ecosystems. For most of our existence as a species, we survived by gathering wild plants and hunting wild animals. We lived within the energy balance of climax ecosystems - altering our environment (as every species does), yet maintaining homeostatic, reciprocally limiting relations.h.i.+ps with both our prey and our predators.