Planning for the future means having an objective and then assigning resources so as to meet it. Without setting an objective we can still set the bounds by considering the limits to resources; in particular, energy.
Let’s assume that people are wise enough to choose not to imperile their future. In using the economist’s expression, we choose to live off the interest rather than the principle. For people needing energy, they would take energy for themselves but leave enough so that other life forms can survive. This enables all life forms to continue and should enable people to continue to utilize large quantities of energy. In short, this future ensures sustainability and human advancement.
A rough bounds for the amount of energy available from vegetation is 2.048 zettajoules (1). The following table gives an estimate of the number of people of various technological levels (2) who can live on the Earth given this energy limit. The number is the increase over our current population.
| Technological Level | Increase |
|---|---|
| primitive human | 85.38 |
| hunting human | 34.28 |
| subsistence agriculture | 16.23 |
| advanced agriculture | 11.27 |
| industrial human | 4.24 |
| technological human (US 1971) | 0.92 |
| Canada (2003) | 1.09 |
| world today | 4.65 |
| Future | 0.17 |
Kardashev’s scale (3) presumes that future higher technological levels need more energy. The future civilization, to acheive the next technological step, will thus need an exponentially increasing amount of energy. Yet, the future population would have to number less than today’s population. For example, even if we tried to get everyone on Earth living at the same technological level as those of the United States of 1971, we’d need fewer people than today. This is shown in the table.
Let’s say an objective of our civilization today is to acheive a higher technolgoical level. This means that given Earth’s finite energy supply, the only way for us to achieve this is to reduce the number of people. This assumes we are wise enough to also choice a sustainable future.
This is a first estimate in energy calculations.
(1) Zetajoules
(2) Reference Book
(3) Kardashev
Example lifestyles for different technology levels;
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