Three Futures for Earth

Copyright © 1991 Jon Roland

At the Branching Point

Our descendants, if they are to remain civilized, will have to live in cities that are sealed, compact, and self-contained, designed and operated like starships that carry their inhabitants into a distant future using only the resources they bring with them.

If we do not soon build and move into such starship-cities, we will rapidly return to the stone age, and in doing so, we will destroy what is left of the natural ecosystem, leaving Earth a barren wilderness, inhabited only by a few wandering bands of desperate nomads.

What cannot endure is the present pattern of scattered open cities, towns, suburbs, and farms that make use of any technology beyond the neolithic. In the long run of more than a few hundred years, no such settlement pattern is viable, no matter what technology we may develop.

If we do choose starship-cities then we can allow most of the natural ecosystem to return to something like its original state before Man, or even help restore it. Human civilization could then endure for the millions of years that remain to the Earth, sharing the planet with our fellow lifeforms.

The many futures that lie before us fall into three distinct major alternatives, and our generation stands at the branching point among those alternatives. It is possible that the moment of choice has already passed, but we may still have a few years left to make that choice.

The third alternative is to establish civilization in space colonies, from where it might some day return to restore a wasted Earth and build the kinds of starship-cities that, had they been built in our generation, might have avoided the loss of the many species that will occur.

The main impediment to solving all our economic, social, and ecological problems is our present commitment to living in open, scattered habitats. Civilized humanity can no more go on living that way than a man could long live after his skin was stripped off and his body was spread out over a large field. Until we can abandon that pattern all of our other efforts to solve our problems are exercises in futility.

Before we consider the options of starship-cities or escape from Earth, however, we need to look at the options of continuing our present course and of adopting the many proposals for managing the planet that do not involve moving into starship-cities, and see whether they really lead to different outcomes in the long run.

Alternative Zero: Minimal Management

The prevailing world order is characterized by competition among shifting coalitions united for short-term goals, with social and governmental institutions marginally adequate for managing conflict and for making short-term investments in projects whose benefits would not be efficiently recaptured by investors of smaller size.

This order has been productive in satisfying short-term human demands, but offers dismal prospects for avoiding long-term difficulties. Despite decades of concern about the ecocrisis, we continue to temporize and to avoid seriously confronting the terrible decisions that must be made if both human civilization and the natural ecosystem are to survive much longer.

Most experiments in centrally-led or directed social engineering on a scale larger than a village have been unsustainable for more than a couple of generations, the main exceptions being leadership of countries subject to long-term external military pressure.

Traditional economists, paid to tell their clients how to make money, will argue that the market is adequate for managing the depletion of resources, that as prices rise, technology will make new reserves available and substitutes will be found. However, this doctrine is little more than a naive faith in the operation of a system that is not well understood, and the resource limits which ecologists warn about are not the economists' proven reserves but price-productivity limits, which economists seldom consider, but which are very real, if somewhat complex (see box, Life-Support Systems).

Interestingly, fossil fuels are not among the most critical resources likely to halt growth or precipitate collapse. After factoring the real costs of existing forms of energy, solar energy is already cost-competitive with fossil fuels, even using inefficient ground-based (as opposed to more efficient space-based) collectors. If combined with hydrogen as a medium for distribution, it is likely to be adequate. However, the cost of converting to its use may very well be great enough to trigger economic decline, especially if conversion must be done too rapidly.

The critical resources beside fresh water and topsoil that may turn decline into rapid collapse are strategic metals like cobalt, chromium, platinum, molybdenum, tungsten, and manganese, although it is likely that before their price-productivity limits are approached, access to the few areas from which they are produced will be denied by international upheaval and political instability.

Even without that, we can expect serious supply problems by the middle of the next century of enough of the strategic metals to threaten the viability of the world industrial economy, unless we take measures like mining asteroids, which could buy some time for industry, but would do little for food production, and the extensive use of which would leave Earth covered with toxic metallic waste.

The present international order, and most political systems, depend for their stability on continued economic growth. If growth fails, as it inevitably must, then the world situation could rapidly become unmanageable, accelerating the decline until it becomes catastrophic.

During such a period of decline, ecological concerns will be submerged by economic distress, and such feeble attempts to protect the environment and conserve resources as may have been achieved will be swept away.

It is ironic that at a time when many countries are turning away from command economies toward democracy and market economies, they are probably doing so too late for the transition to do them much good. The market system, unconstrained by adequate ecological controls, is an unguided missile, which flies high and hits hard.

During decline, the world industrial economy will not reduce the rate at which resources are consumed. It is actually likely to become less productive and more wasteful, especially if major parts of it revert to the command model. Within a few decades it will begin to push the price-productivity limits of several critical resources, whereupon the downward slide will turn into rapid collapse, if it has not already done so due to instability alone. [See "The Disturbing Implications of World Dynamics," THE FUTURIST, March 1971.]

What we can anticipate, with this minimal management, is that even with technological advances, rising resource costs will bring about economic decline, which will in turn bring political instability and a reversal of population growth from starvation, disease and warfare.

After a few decades of more and more rapid decline, industrial civilization will undergo a rapid collapse to a pre-industrial level, and world population will drop to less than half a billion within a few decades. Humanity will then go into a long, slow downward slide, leading eventually to the stone age, reaching a world population of probably less than a million within a few thousand years.

It is difficult to say when the critical point will occur, and the decline will begin. It may have already been reached. If not, it is likely to occur within only a couple of decades. Once decline begins, it may become impossible to rally support for an alternative course.

Alternative One: Scattered Conservation

Most of the proposals for confronting this predicament call for people to reduce their consumption, conserve more, recycle more, bring population growth to a halt, or perhaps begin to reduce it, but to continue to live scattered over the landscape, and to continue to use the natural ecosystem as our life support system. Many speak of such measures, if adopted, as leading to "sustainability" of some kind. However, such discussions usually fall short of specifying what is to be sustained, and for how long. A hard look at such proposals shows that taken together, they do not in fact give us a system that is truly sustainable.

This "green" solution is also unable to support the technical capability needed to either avoid departures from the regimen it envisions or to protect humanity from major natural hazards, such as asteroid impacts.

If we continue to live in scattered settlements, all of the conservation measures we might take that are remotely feasible only buy us a few decades at most. For some that might seem enough, but others will ask whether it is worth the trouble.

Even if we could halt world population growth within a decade, and instituted such a conservation regimen for a world population of more than 6 billion, then we would begin to hit price-productivity limits around the year 2050, and by the year 2150 we would be in a rapid collapse back to the stone age. By 2500 the world population would probably be less than 100 million, mostly at war with each other.

It is not likely that humanity would soon become totally extinct, but is also likely that unless or until it did, the natural ecosystem would never recover, because desperate humans would quickly descend upon any area of recovery, humans who would eventually lose all memory of the heights which civilization had once attained.

One is compelled, therefore, to conclude that over time spans of more than perhaps a century or two, Alternatives Zero and One converge, and must be considered, if we take a longer view, to be only one alternative, unless we can use the time we buy to open another alternative.

However, we have a poor record of using the time we buy. The so-called "Green Revolution" was sold as something that could buy us time to bring world population growth under control, but most of that time has now been wasted.

Alternative Two: Compact Conservation

This alternative can best be understood by distinguishing the life-support system for humanity, or arcosystem, from the natural ecosystem (see box, Terminology). At the moment, they largely coincide, but this need not always remain true. The fact that the life-support system for humanity is in principle completely separable from the natural ecosystem is often overlooked by environmentalists.

We can imagine self-sustaining colonies on other planets or in space, or multi-generation starships that could support large populations for thousands or millions of years. Now, if instead of (or in addition to) sending these cities off into space, we build cities like them on Earth, we have the design for the kind of cities we will need to live in if civilization is to survive on Earth. Such cities would be totally independent of the external environment for everything except energy and as a sink for waste heat.

Such starship-cities could use space solar power, but geothermal energy would probably be sufficient for all of their needs. If all humans were withdrawn into such cities, the natural ecosystem could be allowed to recover, and the surface of Earth could be returned to a natural garden, available for limited recreation. Surface agriculture would be replaced by internal food factories.

Such a starship-city does not require technology much beyond the present state of the art. There are many details of design that would have to be worked out, similar to the problems now being solved for a potential manned mission to Mars, but we could design and build a working prototype within a decade or two that would be a single structure, perhaps two kilometers in diameter, that could support a half-million persons and allow for continuing repair while in use, giving it an indefinite life span.

Life in such cities could be spacious and rewarding. People could visit the natural outdoors, as long as they did so in controlled ways that did not risk loss of strategic materials or excessive impact on the wilderness. It is likely that few if any of its internal systems would be biological, except for the humans themselves. These cities would be able to sustain a vigorous civilization.

The important thing is that such cities would be sealed. They would recycle everything, even air. They could be sited almost anywhere: on land, on the surface or bottoms of oceans, or deep underground. However, exposure to air or water would subject them to various hazards, such as weathering and corrosion, so the best place for them is likely to be underground. That would also be the best place to take advantage of geothermal energy, and to enforce conformity to their rigid conservation regime.

The issue can be better understood if one considers a human habitat, whether a city, a single-family dwelling, or a spacesuit, as an arcosystem surrounded by an envelope or membrane which is permeable to a greater or lesser degree to the flow of energy and materials. This envelope is the interface between the habitat and the environment.

There is a cost for making that membrane impermeable to a given degree to a given substance, and that cost is more or less proportional to the area of the envelope. The ability of the enclosed settlement to sustain that cost, however, depends on the ratio of the area of that envelope to the volume enclosed. If that ratio is too large, the cost is unsupportable. The area of the interface for the kinds of scattered settlements we build now is effectively infinite.

What this means is that for almost any technology we can conceive, it is unlikely that once the economy is compelled to recycle all of its materials human civilization can survive for very long unless it does so in sealed cities.

What about nanotechnology? It may make possible many marvelous things [See "Nanotechnology: The Promise and Peril of Ultratiny Machines," THE FUTURIST, March-April 1991, p. 29.], but it will not enable humanity to overcome the laws of thermodynamics. With nanotechnology, we could build starship-cities more rapidly and at a much lower cost. It may also make possible starship-cities that are smaller, perhaps housing only a few tens of thousands of persons. Assuming, however, that it does not result in replacing human beings with something quite different, a starship-city will still need to have a minimum size to support a viable society with a rich culture. Almost any system of beings with independent volition incurs a certain minimal risk that the rigid conservation regime will be violated over geologic time. So even nanotechnology will not enable us to escape the need to abandon scattered settlements to avoid the collapse of civilization. The ultimate constraint on settlement design is human nature.

For this reason, family-sized habitats are likely to always remain too small, and detached houses, if any, will have to be built only of renewable natural resources, and only a small number of them could be permitted, perhaps for people like park rangers and naturalists.

There is an optimum size for a starship-city, ranging from a diameter of a few kilometers to less than about half a kilometer, and housing a few hundred thousand to a few million persons.

However, one must ask why the starship-city concept could not be extended to make the entire planet the arcosystem, perhaps bringing the natural ecosystem into it as a part of it. This is a variant on the Spaceship Earth concept.

In principle, this could be done for a time, at a great energy cost, but it would not be sustainable. Even if every species were re-engineered to participate in the recovery of waste materials and pollutants, they would not be able to recapture it all or keep up with the load, and the energy cost to them would be too high for them to sustain their participation without continuing inputs of energy which would be unsupportable in the long run, and which would eventually reduce them to a small number of domestic species.

The notion of Spaceship Earth is not quite right. What is needed is Spaceships on Earth.

How long could civilization endure in such cities? There is no reason why it could not do so for as long as life remains possible on Earth. The sun is getting hotter, and it is expected that that trend will result in a runaway greenhouse effect in about 500 million years, causing Earth to become something like Venus is today. Sometime before then the heat will probably reduce the viability of life on Earth. We might have, say, 100 or 200 million years during which the surface of Earth remains a reasonably pleasant place to visit.

Beyond that, we have about 5 billion years before expansion of the sun will destroy the planet. However, it is possible for human civilization to endure in underground cities, despite the runaway greenhouse on the surface, for the entire 5 billion years.

The key point here is that if civilization is to be sustained for more than another century or so, and if the natural ecosystem is not to be destroyed, then there is no alternative to such sealed, compact starship-cities. Any compromise, even seemingly minor ones, leads to collapse within a remarkably short period of time.

The critical problem for our generation is that it takes time, resources and leadership to build these starship-cities, especially the first few. If we do not begin soon, we will not have time to complete any before the onset of collapse, after which it will be difficult for more to be built by anyone but those already living in them.

The first few starship-cities will be much more expensive than conventional buildings, although the cost must include not just the infrastructure but everything their inhabitants will need to make a living in them. That cost could approach a million dollars per inhabitant, although it would be amortized over geologic time.

It would be difficult for the present world economy to divert enough money to build more than about one a year, each with a capacity of a million persons. That would take about two-thirds of the world's present military budgets. That means that during the next century, toward the end of which the world situation outside these cities is likely to become totally unmanageable, it will probably not be possible to build enough for more than about 100 million persons.

This will not be a solution for the 5.5 billion people now alive. For Spaceship Earth these would only be lifeboats. There is no solution for most of the people now alive.

Those starship-cities may also need to be warships, in which all the inhabitants are crewmembers. They are going to have to be secure against attack by those who remain outside, many of whom are likely to become a threat. This is another reason for building underground.

Such cities are also unlikely to have places for persons who lack advanced professional skills. All of the kinds of jobs available now to lower-skilled persons would simply not exist in such cities, and supporting a high proportion of nonproductive dependents would lead to a highly unhealthy social situation that would ultimately jeopardize the viability of the societies that live in them. We are already beginning to have to face this problem in existing high-tech societies, even without starship-cities.

If the starship-cities can continue to provide essential services for some of those remaining outside, they may be able to trade those services for getting those outsiders to protect what remains of the natural ecosystem from the rest of humanity, until the outsiders die back and revert to the stone age. By that time, the cities should have been able to grow in number and capacity to the point where they can bring the remainder in, leaving the natural ecosystem totally separated from human beings, except as occasional visitors.

The greatest challenge for these cities would be the tension between their inhabitants and those who remain outside. There is no way to avoid the inequity between those who get to enter the lifeboats and those who remain behind on the sinking ship, especially if they have to continue to deal with one another.

A few may continue to live outside the cities, at a stone age level, in which case humanity may ultimately divide into two species: City Man and Wilderness Man.

Alternative Three: Space Colonies

Starship-cities on Earth may not get built, or survive if they are. They will be vulnerable during the difficult times that will prevail on Earth. Being built underground may not provide enough protection. For human civilization to survive, it may still be necessary to build them elsewhere. The most likely sites are Luna, Mars, and the asteroids. We already envision terraforming Mars to make it more like Earth, but that is not necessary. The best place to build starship-cities is beneath the surface. There human civilization can continue to survive and flourish, and, eventually, when things settle down on Earth, return there.

It is likely that the first major terraforming project for humanity would be Earth itself. If samples of the DNA of various lifeforms were preserved, it might be possible to restore Earth to something like its original state, before man. Many species would inevitably be lost, but enough might be saved to enable Earth to return to some semblance of its original state.

Aside from providing another place to preserve civilization, long-duration space missions may offer the only way to pull together the resources to build prototypes of the kinds of starship-cities that we need on Earth. A colony on Luna or Mars would have to solve many of the same kinds of problems we would have to solve to build spaceship-cities on Earth. It might be easier to get political support for funding starship-cities in space than on Earth.

What is at Stake

We have a grim dilemma. If we continue along our present course, we can pretend that we are doing the best we can for the billions now alive, but we will be unable to do much. The result will be the loss of a civilized future and of Earth as a beautiful abode of life.

Or we can divert some of the resources which might otherwise go to meet rising demands from people we can't save anyway, and try to save the future, in which trillions of people can live decent lives for millions or billions of years. The decision is ours to make, in this generation. In another decade or two, it is likely to be too late.

Even if we were only talking about a world population of 100 million persons, living over 100 million years, at 25 years per generation, that is 400 trillion people whose lives depend on us making the right decision. That is 100,000 people for every one now alive on Earth. And there is no fundamental reason why we could not have a million starship-cities on Earth, with a population of 1 million each, for the entire 5 billion year life expectancy of the planet. That would be 200 million trillion whose lives depend on us, or 50 billion people for every one now alive on Earth.

If humanity returns to the stone age, we might see, at most, a million persons living for the 100 million year period the surface of Earth is likely to remain habitable. Their lives are not likely to be of high quality, but even ignoring considerations of quality of life, that is only 4 trillion persons over that span, or about 1000 persons for every one now alive.

How many of us imagine we have to make a choice between the life of 1000 persons, living in misery, and the lives of from 100,000 to 50 billion, leading full, satisfying lives? But that is the choice all of us, in this time, have, whether we care to admit it or not.

However we make this choice, let us at least be able to say to those of you who may come after us, a million or even a billion years hence, that some of us, at least, thought about you while we made that choice, and if too many of us lacked the vision and the courage to put your needs ahead of our own, and to do what was right for you, at least some of us tried.

About the author

Jon Roland is President of the Vanguard Research Institute, a research foundation, and of the Starflight Corporation, a computer consulting firm. The address of both is 1755 E Bayshore Rd #9A, Redwood City, CA 94063.

Life Support Systems

Humanity evolved as a hunter-gatherer with a technology of stone, wood, and bone, and as such developed a territorial instinct that continues to impel us to want to spread out over the landscape. Even at that level of technology, humanity managed to drive a number of major species into extinction. Estimates vary of how many people the natural ecosystem supported or could have supported during this stage of human evolution. Some estimate the number who actually lived on Earth was only about 4 or 5 million, but others think that with oceanic fishing it could have supported as many as 100 million.

That is likely to be the upper bound on the carrying capacity of the original natural ecosystem for humanity in the long run. While technology has enabled humanity to increase the carrying capacity of Earth beyond that number, temporarily, by drawing on minerals from the larger geosystem, it has done so by partially, but not completely, replacing the ecosystem in its role as the life support system of humanity. At the same time, it been used to progressively destroy that ecosystem, without being used to permanently replace it.

If humanity had to revert to the ecosystem as its sole life support system today, it would find that the carrying capacity of the ecosystem has been greatly reduced from what it had been, probably to less than 10 million. At current rates of degradation, within a century that carrying capacity is likely to be less than 1 million.

About 8000 years ago, humanity began herding domestic animals and planting crops, and in doing so began a process of more and more rapid degradation of the natural ecosystem. Forests were cut down, and topsoil was allowed to erode. Irrigated farmland became salinized, and water tables dropped.

At first, people lived close to where their food was produced, and returned the nutrients they used to the soil not far from where they were extracted, but as people began to live in towns and cities, they increasingly dumped those nutrients into landfills, streams, and the ocean, from which they are no longer readily extractable, and from which they will not again become available except through the long process of tectonic recycling, which takes about 600 million years.

The key, however, to the rapid growth of humanity we have seen in the last two thousand years has been the discovery of accessible sources of critical elements, mainly the metals, and technology to use them. It is upon the supply of these critical elements that the modern world economy, and the current large world population, depends.

The population of Earth is now about 5.5 billion. It continues to grow at the rate of about two percent per year, enough to double it every 35 years. However, world food production is now probably nearing the limits of what can be achieved using the kinds of farming methods that most of the people of the world are likely to be able to actually use.

Our present level of food production depends heavily on inputs of energy, mostly from fossil fuels, and of critical minerals, mostly metals, both of which are being depleted. More and more fertile land is being lost to salination, erosion, depletion, desertification and development.

A growing system whose growth depends on a finite supply of external materials must eventually reach the limits of those materials and enter a phase in which its growth ends and it can draw only on internal reserves. Projections of how long the world industrial economy has before reaching this point are sometimes confused by different definitions of resources and measures of their supply.

Economists speak of proven reserve supplies as the amount of some resource available at current prices from sources already discovered, and of projected reserve supplies as the amount available at current prices from sources expected to be found with current methods of exploration.

Economists sometimes criticize the concerns of conservationists about resource depletion by pointing out that as resources are depleted, their prices rise, and that when they do, the amounts of proven or projected reserves also increase, sometimes faster than the rate of depletion, and that even when they don't, new technology and substitutes become available.

However, it is not proven or projected reserves that are the applicable measures. The law of diminishing returns on investments of resources and capital yields a price-productivity supply: how much of a resource, with all of its substitutes, can be economically extracted at the highest price the market can sustain. That is the real limit on growth.

For this purpose, a "resource" is not a specific material, but a critical function which can be played in an economy by a material or any of its substitutes. Actual materials may be components of more than one such function.

Estimates vary of what the price-productivity supplies of various critical resources may be, but the most critical may be ones that are not usually treated as commodities — fertile topsoil and potable water.

The world industrial economy, as it is presently structured, cannot continue to grow if the real costs of certain critical resources rise by very much, no matter how much may remain, using any of these measures of supply. It is balanced between growth and decline. At a certain critical supply and cost level of these critical resources the economy will start downward, and once it does, there may be no reversing it. This decline may have already begun — about 1973.

Some have introduced the concept of the biosphere, a living system in which all materials are recycled and only a moderate amount of energy is used to do so. The primary biosphere is the natural ecosystem of the entire planet, but some envision smaller biospheres, isolated from the primary one, consisting of balanced communities of various life forms, which may include human beings and serve as the life-support system for them.

Unfortunately, the concept, while useful for doing input-output and other kinds of analyses of the communities when only non-technical species are involved, is inadequate if technical humans are included. If they are, then one must also consider what kind of technology and economy they are to have, and include that in their biosphere.

Let us assume we can somehow rally humanity to stabilize the world politically and economically, and implement most of the suggestions environmentalists are making for recycling and conserving, enough so that we no longer draw on external reserves, but depend entirely on re-use of internal stocks. Let this include proposals for converting to the latest methods for "sustainable" agriculture, for halting further destruction of natural habitats, and for substantial reductions in environmental contamination. Let us further assume, however, that human habitation patterns remain much the same, with people scattered over the landscape. This would surely buy human civilization and the natural ecosystem some time, but how much? Is such a regime really "sustainable"?

What is needed to answer this question is to do a thorough input-output analysis of the world economy. There will inevitably be some losses to the environment that are unrecoverable. Once an element gets spread too thinly, it is no longer feasible to reclaim it. How long can such a state of affairs be sustained before breakdown occurs?

To get a handle on estimates of how long it can be sustained, it is useful to use the Thirty-Seven Percent Rule: If an economy begins with a given internal reserve on which it depends completely, if it can tolerate a loss to the environment of sixty-three percent of that reserve, and if it loses 1/n of that reserve each year, then for values of n greater than about 10, it can endure for about n years before it collapses.<1> This value of n, which we may call the system endurance, provides a convenient figure of merit for comparing technologies and economies based on them.

If one does a simple input-output analysis of any of the technical economies history has seen or which can reasonably be projected, and any reasonable variations thereof, it is difficult to find values of n greater than about 20 for most strategic metals, or greater than about 2000 for topsoil.

Prevailing values of n for the present world economy are on the order of about 5 for strategic metals and 100 for topsoil. Proposals to return to a simpler, 19th-century style of living, and to make use of known methods for "sustainable" organic agriculture, might, at best, increase these values to 100 and 5000.

Unfortunately, even returning to a paleolithic technology would not save the ecosystem now. Humanity was on the way to destroying it with no more technology than the knowledge of how to herd animals, cut trees with stone axes, and use wooden plows. Even if we deprive humanity of the tools for its own destruction, we cannot deprive it of the knowledge to do so.

Futurist Methods and Ethics

Futurists have often found it is much easier to agree on which futures are more desirable than on which are actually available. As we approach the year 2000, it seems that many futurists are having difficulty seeing beyond that year. It is time to step back and take a long, hard look at where we are, where we can go, and how we might get there.

For this purpose the conventional approach of projecting recent trends and their interactions into the near or midterm future is inadequate. To see what our real options are, it is better to begin with a view over geologic time, look at physical constraints on what is possible, then zoom down to the present. It is this zoomdown approach which shows us to be at a critical branching point, and that the options which seem at first to organize themselves into four or more main alternatives are actually only three.

The most important trends, for purposes of choosing alternative futures, are not of political, economic or technical progress, or of ecological regress, but of current patterns of management of human affairs. These are the control variables by which we might apply leverage to the course of history.

Recent trends toward rejection of central governmental management of social and economic problems in favor of market forces indicates that people seem increasingly inclined to stake their future on the free interplay of the marketplace of goods, services, and ideas in a cooperative international framework of democratic societies. However, this may also mean increased avoidance of visionary leadership in favor of minimal reaction to unfocused and conflicting popular pressures.

There is a futurist ethic which is based on the futurist paradigm that regards each moment in time as a branching point for a countless number of alternative futures that arise from each of the decisions we might make. In this paradigm, we cannot avoid deciding. There is no such thing as no decision.

We may not be able to foresee all the consequences of our decisions, but we are objectively responsible for the outcomes regardless of whether we can foresee them or not. We are morally responsible for those outcomes to the extent that we can foresee them, and for doing the best we can to foresee them. That responsibility does not end in a decade or a century. It goes on to the end of time.

We tend to discount the interests of the future, and if the rate at which we do so is more than about 21 percent per generation, then the interests of generations beyond three — ourselves, our children and grandchildren — amount to less than those three generations, and we dismiss distant posterity, perhaps arguing that they can solve their own problems.

If, on the other hand, we are to give any weight at all to generations beyond the next three, then the discount rate is less than 21 percent, and the interests of all future generations outweigh those of the next three. For the judgement of history, a discount rate of more than 21 percent is immoral, and we may define futurist morality as discounting the interests of future generations at less than 21 percent per generation.

Other Starfaring Races

Our example suggests, if we are typical of technical civilizations in the universe, that once an intelligent species leaves the hunter-gatherer phase and begins the practice of agriculture, it has only a few thousand years to make the leap to a sustainable starship civilization. If it misses that window of opportunity, it will descend into a long dark age and take the rest of life on its planet with it. Very few may make it.

The physicist Enrico Fermi once looked up at the sky and asked, "Where are they?" What he meant is that if starfaring is possible, and it seems likely that it is, then it should be possible for a single such species to expand throughout the galaxy in only about 1 million years, at an average speed of .1 lightspeed, pausing at each outpost to build more starships. Assuming we are not the first in the galaxy, then why has Earth not been visited by aliens every few years?

The answer may be that it is being visited that often. For a starfaring civilization to last long enough to get to another star, its members must live for many generations in starships. When they do encounter planets, they continue the same lifestyle, in starships, sited underground. There could be trillions of aliens from millions of starfaring species living here on Earth, beneath our feet, and we would never know it. They may have been here for longer than we have been, or even for longer than there has been life on Earth.

If they have a continued interest in scientific research, and they found a species on the surface that was evolving toward a technical civilization, there would be a natural temptation to intervene just enough to give that species a chance to bridge the transition to long-term sustainability without unduly influencing the form it would take. We could be one of their experiments. If we are we can hope that their intentions are good and that they know what they are doing.




Ecosystem, Biosphere


Society, Economy, Polity


Geology, Meteorology, Oceanography

Ecology, Biology, Paleontology

Arcology, Ekistics, Urban Studies

Sociology, Economics, Politics, Anthropology, Archaeology


Ore deposit, Aquifer, Watershed, Ocean, Plate, Atmosphere

Habitat, Community, Species, Topsoil, Carbon Cycle, Energy Flows

Arcopolis, City, Utility, Highway, Agriculture

Individual, Family, Race, Nation, Government, Company

Renewal Period

600 million years

100-60,000 years

200-5 billion years

25 years

Human Function

Minerals, Water, Air, Shielding

Present Life-Support, Aesthetic Pleasure


Identity, Purpose, Companionship, Support, Discipline

Present Status

Being depleted

Being destroyed

Scattered, Unsustainable

Fragmented, Short-Sighted

Desired Status



Compact, Sealed, Self-Sustaining

United, Committed to Long-Term Civilized Survival

The above table provides some sense of the relationships among the various elements it indicates. The term arcology was first used by Paolo Soleri, a blend of architecture and ecology, but he also used the term loosely to refer to an urban megastructure of the kind he envisioned. Here we use the term arcopolis to refer to such a city, and arcosystem to refer to an interconnected network of them spanning a planet.

At present human civilization depends on both the geosystem and ecosystem for life-support, but this need not always remain so. It is possible to build an arcosystem sustainable over millions or billions of years that is largely independent of the geosystem for anything except shielding and perhaps geothermal energy, and completely separated from the ecosystem.

Since increasing radiation output from the Sun will trigger a runaway greenhouse effect on Earth in about 500 million years, there will not be enough time for another recycling of the lithosphere by tectonic subduction, which will take about 600 million years. In geologic time, we are in the final stretch.

<1> The amount R remaining after n years is given by R = (1 - 1/n)n, which tends toward 1/e or about .37, or 37 percent, as n increases:

n 10 100 1000 10000 1000000
R .349 .366 .3676 .3679 .3680