Will Humanity's Lease Expire?

Until recently there has been no general concern about the long-term capacity of the physical world to meet our expanding wants. Now that such concern is both necessary and widespread, all of us are subjected to conflicting and often inconsistent advice on the direction to take. Mankind has no long-term strategy to guide short-term policy. It is easy to accept the idea that current policy should be consistent with a longer-term view, but this is difficult to achieve in the absence of agreement on what the longer-term options look like or which of them we wish to choose. In modern societies with representative governments, consistency between long-term objectives and short-term actions is hard to attain in any case, for governments must be responsive to short-term demands that often are in conflict with longer-term goals. Nonetheless, clearer public understanding of long-term options favors a climate in which greater reconciliation between current policy and long-term goals is possible. With that in mind let us examine future modes of occupancy.

All civilized men are miners. Primitive hunters and gatherers were not; they depended upon and were limited by the current output of natural systems. But from the time man first domesticated goats and made bronze, he has been mining the earth's soil and rock, dispersing our materials, and degrading the environment.

However, we are not exclusively miners. We still make use of current biological output. In the case of agriculture, we have modified natural systems so as to increase greatly the earth's yield, apparently on a sustainable basis. This use, however, is not infinitely expandable; the supply of agricultural land is finite and limits to the efficiency of photosynthesis may be expected. Thus, while agriculture offers partial escape from the adverse effects of the mine, it uses exhaustible resources, meets only a limited range of needs, creates environmental problems, and is itself subject to capacity limitations.

Air and water are also complex resources which render direct amenity services to each of us and assimilate our wastes. While they are renewable in most respects, they are not so in all respects, since they can be permanently damaged.

All of these limits are aggravated by an increased scale of human activity. Because of growth in both numbers and per capita consumption the draft on resources and burden on the environment are increasing at a startling rate. The relentless logic of Malthus that, given fixed supplies of land, we could not expand food production fast enough to keep pace with population growth has not yet been verified. Still, it is impressive to observe how rapidly exponential growth threatens to exhaust finite stocks of conventional, nonrenewable resources or available land, and most of us have become aware of the onerous burden of pollution that endless growth implies. These consequences loom even if technological advances extend the availability of conventional resources and the capacity to abate pollution.

While growth shortens the time to exhaustion of finite resource stocks, permanent human occupancy of the earth cannot in any case be based on the use of conventional exhaustible resources. However successful we are in finding deposits or in recovering materials from lower-grade sources, eventually we use up our supplies.

Can the dilemma posed by depletion be avoided? Essentially two paths are open to man in order to secure permanent occupancy. One is to aspire to a modest but sustainable place in the natural system by changing to a technology that is non depleting in character. Man once held such a sustainable place when his numbers were few, wants purely biological, and technology nil. Regaining such a balance would mean reliance upon current energy flows from the sun and on the biological cycling of materials. It would not rely on the continuing net acquisition of exhaustible materials.

We might hope to manipulate the natural system through sophisticated biological methods and more efficient capture of the energy flow from, for example, sun, wind, and tides, so as to maintain numbers and a high standard of living. The more restrained our expectations with respect to population size and living standards, the more promising the outlook for this mode. Even so, it's difficult to see how this system could avoid degradation over time.

Many uses of materials are inherently dissipative, and it is hard to imagine that we could divert a current energy flow large enough to permit us to recapture that which is dispersed. As dispersion proceeded we would lose access to our initial stock of exhaustible materials, including metals. The loss of metals, hence machinery and transport, would limit our capacity to capture and utilize current energy flow. Regression in population and income would appear inevitable. Advocates of this mode might view such a result with equanimity, contending that it is still consistent with human happiness and the health of the planet. Indeed, on a sufficiently reduced scale, this mode is viable.

The other path would be a calculated effort to escape the constraints of resource exhaustion through new technologies. It differs from previous constraint-releasing advances in that it would not simply rely on enlarging the conventional supply of exhaustibles, but rather would seek to replace them with inexhaustible resources. The difference is between a temporary reprieve and a permanent solution. The second path means finding an inexhaustible source of energy as a prerequisite to other technology that would make use of more common materials. Given ample energy, we might make a direct attack on entropy, using common rock and sea water as resources, or perhaps we could reach for the alchemists' dream of elemental transmutation.

Even this approach would not be without limits on growth—dissipation of heat from the earth's atmosphere and physical space still pose limits. (Presumably we could learn to synthesize nutrients chemically, so photosynthesis and the supply of agricultural land need not limit us). Of course, an encounter with the heat limit also could be greatly postponed by more attention to efficiency and less use of heat-using technological processes. The important point is that, while we might face limits to the magnitude of activity at any time, we could hope to escape the time limit implied by exhaustion. And, if this mode is combined with population restraint, it carries the potential for a higher standard of living for both developed and less developed countries. By contrast, when measured by current values, the first path implies a lower standard of living. Although each path admits of many variants, the strategies suited for each path are antithetical in important respects. An interim strategy could preserve the option to choose between the two modes, but that decision cannot be indefinitely deferred.

There is no assurance that the second mode can be achieved. Is it not more risky than the first? The answer is probably negative, for if the second path proves impassable, this does not preclude reversion to the first, although, depending on population size at the time of transition, great suffering and a dramatic reduction in numbers would be likely.

There is some risk in postponing the decision. The constraint-releasing option is perishable—we must seize it soon or forever lose it. Timing is very important. Since time is required to perfect constraint-releasing technology (if indeed it is successful), exhaustible resources should be viewed as buffer stocks to be drawn on while the desired technology is perfected. If we continue to consume exhaustible materials without advancing to a technology able to transform or transmute plentiful materials, then we may no longer have in stock the energy or the quantities of concentrated elements needed to secure the transition. If we tarry too long or move too far down the first path, abandoning much of our technology as we go, then we forfeit the option for the second path—in effect we choose path one for our heirs, if not for ourselves.

Mankind is largely unaware of the need for choice. Instead, we mill about, increasing our appropriation of the stock for current consumption but not turning in a definitive way toward constraint-releasing technology of a sort that allows permanent occupancy. Is there still time to effect the transition before encountering resource constraints? Many doomsayers who think not are in fact expressing a preference for a romanticized version of path one. To the extent that they are also technological Luddites, there is a self-fulfilling element to their prophecy.

But if path two is selected, a prudent first step would be to seek a more efficient transformation of the natural capital represented by resource stocks into the constraint-releasing technology of the future. A consumer society that uses stocks only to increase immediate gratification is inimical to the second strategy. An antitechnological bias that denies resources for the development of new technology also frustrates the second path. On the other hand, measures to conserve exhaustible resources through more efficient use, recycling, or substitution of renewables are consistent with the second strategy. Policies that restrain our rate of use of exhaustible resources, extending the time period over which the stock is used, allow a longer time for transition to occur. However, such conservationist measures need to be combined with a technical strategy if they are to contribute to the success of the second option. Thus, the conservationist, preservationist, and environmentalist biases present in much of the current discussion can be reconciled with the second strategy, but the antitechnological biases cannot.

While conservation policies permit deferral of the choice between the two paths, ultimately a choice must be made. Our society already is a heavy user of exhaustible resources and there is danger of overstaying that mode. If we opt for the second path, we must do so while resource stocks allow time, energy, and materials for possible success. Also, we must have continuity with past technical achievements. We may be able to get there from here, but not if we wander too far away from the technological sophistication already attained. We must remember that we can always fall back on the first course, provided no cataclysmic damage has been done to the ecosystem in the process. Hence the manner in which we proceed is also of great importance to man.

In sum, long-term human occupancy of the earth on the present basis is not viable. The alternatives are either path two to escape resource exhaustion while retaining income aspirations or path one, based on current flows, with population and income being trimmed as necessary. In either case there are limits (though quite different ones) to the scale of human activity at any time but no necessary limits to its endurance.