It is the view of SPGN that there is ample evidence that even our present population of approximately 22 million is unsustainable, and that further growth will only make the position worse.

Notwithstanding, visitors to this site may wish to look at the effects on population numbers of different population growth rates by using this calculator.

Although we refer to what follows as a Population Growth Calculator, it is equally applicable to any quantity which grows with time. (Think about dollars in an interest bearing deposit for example). Using the calculator is a simple four step procedure:-

- Type the initial population into the first input field. For example if we are talking about Australia (as we most certainly are) you could type
in 22000000, or perhaps a bit more than that if you want to be super accurate.
- Type the percentage rate of increase into the second input field. For example, type in 2.1 if you want to see what would happen if the growth
rate for 2009 were to continue, or type in 1.3 or 1.4 if you are concerned with the growth rates being proposed by the two major parties.
- Into the third input field, type the number of years over which the population growth rate will apply. For example a politician would probably
only be interested in a period of 6 to 10 years, while an environmentalist would more likely be interested in periods of hundreds or even
thousands of years.
- Click the Calculate button, and study the results.

The results are presented as a set of three numbers:-

**Final population:**This number will often be very large, and so to make it more readable, it is presented in the standard large number format with commas used to separate it into groups of three digits. (The other two numbers will be much smaller, but if they happen to be in excess of 1,000 then commas will also appear).**Number of Australias:**Often, the final population result will be so big, it will be virtually useless. It is divided by 22,000,000 to yield a figure for the number of Australias represented by its value.**Number of Worlds:**Sometimes, even the number of Australias is too big to be of use. Dividing the final population by 7,000,000,000 yields a figure for the number of Worlds represented by its value.**NB.**The largest number which can be displayed by this calculator will depend on the browser you are using. For Firefox it will be 1,000,000,000,000,000,000,000. This number can be stated as one billion trillion. For Internet Explorer, there seems to be no upper limit.

Whether or not a population growth rate is considered realistic will depend largely on the time scale under consideration. For example, if you are only interested in a period of ten years, then a growth rate of 2% might be considered. If you want to ensure that the human race will remain viable for a thousand years, then a growth rate of 1% will be seen to be totally unrealistic. In the following, four categories of people are considered, along with the time horizons they might be expected to adopt:-

**The Politician's horizon.**

As mentioned previously, the time horizon of a politician is assumed to be ten years...two to three terms in office, depending on the frequency of elections. Using figures of 2% growth rate and 10 years duration in the population calculator gives the following results:-Final population: 26,817,877 Number of Australias: 1.22 Number of Worlds: 0.00 There may be some who would think that this looked to be fairly sustainable. What happens after the ten year period is unspecified, and would be of little concern to most politicians.

**The Historian's horizon.**

An historian could be expected to take a broader view, and say that since the arrival of the first fleet, 223 years have elapsed. As a minimum we should make our plans in such a way that Australia will remain viable for at least another 223 years. Will a growth rate of 2% be sustainable over this time span? Using figures of 2% growth rate and 223 years duration in the population calculator gives the following results:-Final population: 1,820,794,713 Number of Australias: 82.76 Number of Worlds: 0.26 Most people would probably think that a population greater than the sum of the populations of China, Pakistan and Bangladesh would be unsustainable in Australia, and they would be right. Let's say that a population of four times the current level would be sustainable in Australia. (It wouldn't, but for the sake of argument let's just say that it would). A few test calculations with the population calculator soon shows that the population growth rate would need to be restricted to 0.624 to achieve this result after 223 years.

**The Archaeologist's horizon.**

A time horizon of perhaps 6,000 years might be adopted by an Archaeologist, as this represents roughly the duration of human civilization. If the human race should survive for another 6,000 years, and we adopt a growth rate of 0.624%, where would we stand. Entering the appropriate figures into the population calculator yields the following results:-Final population: Number is too big to display Number of Australias: 16,198,108,617,668,532.00 Number of Worlds: 50,908,341,369,815.39 Under this scenario, Australia's population would be more than fifty trillion times the current world population!! Most of the population "boosters" in Australia will no doubt ignore this result, saying that it couldn't possibly be true. If they were to study even just a little mathematics, they would quickly learn that it is absolutely correct. As before, we use the calculator to determine what level of population growth would result in Australia increasing its population to 4 times the current value. This turns out to be a growth rate of 0.0231%. By now, it should be very clear that longer time horizons result in smaller permitted growth rates.

**The Paleantologist's horizon.**

A Paleantologist might say that since beings which were recognizably human have been living on this planet for more than a million years, we should be planning for a future which allows the human race to continue for at least this length of time. Once again, using the population calculator, and a growth rate of 0.0231% we get the following results:-Final population: Number is too big to display Number of Australias: Number is too big to display Number of Worlds: Number is too big to display Obviously, we are talking about remarkably large numbers here! Once again we can find the growth rate which results in Australia's population growing by a factor of 4, and it turns out to be 0.0001386%. Even if we were prepared to let Australia's population grow to equal the current world population, we would have to be content with a growth rate of 0.000576%. For all practical purposes, figures as low as this can be considered as zero.