The Next 200 Years by Herman Kahn, William Brown, and Leon Martel

Kahn's regarded as the inventor of scenario analysis, and here he lays out the basic Earth-centered perspectives for 1976 - 2176.

1. Convinced Neo-Malthusian.
Finite pie.
Most global non- renewable resources can be estimated accurately enough (within a factor of 5) to demonstrate the reality of the running-out phenomenon. Whatever amounts of these resources are consumed will forever be denied to others. Current estimates show we will be running out of many critical resources in the next 50 years. The existing remainder of the pie must be shared more fairly among the nations of the world and between this generation and those to follow. Because the pie shrinks over time, any economic growth that makes the rich richer can only make the poor poorer.

2. Guarded Pessimist
Uncertain pie.
Thefuture supply and value of both old and new materials are neces- sarily uncertain. Past projec- tions of the future availability of materials usually have been gross underestimates. One can concede this could happen again, but current estimates seem relatively reliable. Cur- rent exponential growth clearly risks an early exhaustion of some critical materials. Pru- dence requires immediate conservation of remaining resources. Excessive conser- vation poses small risks while excessive consumption would be tragic.

3. Guarded Optimist
Growing pie.
Past technologi- cal and economic progress suggests that increasing current production is likely to increase further the potential for greater production and that progress in one region en- courages similar developments everywhere. Thus as the rich get richer, the poor also benefit. Higher consumption in the developed world tends to benefit all countries. Ex- cessive caution tends to main- tain excessive poverty. Some caution is necessary in selected areas, but both the "least risk** and the "best bet" paths re- quire continued and rapid technological and economic development

Technology and Growth Enthusiast
Unlimited pie.
The important resources are capital, tech- nology and educated people* The greater these resources, the greater the potential for even more. There is no per- suasive evidence that any meaningful limits to growth are in sight—or are desirable —except for population growth in some LDC's. If any very long-term limits set by a "finite earth" really exist, they can be offset by the vast extra- terrestrial resources and areas that will become available soon. Man has always risen to the occasion and will do so in the future despite dire pre- dictions from the perennial doomsayers who have always been scandalously wrong.