Overpopulation
Overpopulation is when the population is too large to be supported by the environment. In worst case the whole population becomes unstable and develops to the verge of extinction.
The population on Earth is steadily growing, and Earth is already showing signs of overpopulation. Colonization of Mars may reduce the problems of overpopulation on Earth, but the cost of transportation is probably too high for this to be likely.
However, overpopulation is also a threat to a colony if the production and consumption is increasingly out of balance. A population does not necessarily have to grow, but if it does, the available vital resources must be considered. Knowing the resource limitation, there must be a limitation in the population's growth.
In Martian greenhouses an overpopulation of certain insects can be a potential threat to the food production. The equilibrium of the artificial biosphere must be taken care of. Excessive amounts of bacteria might have a similar effect.
Contents
Limiting a population's growth
This paragraph lists a number of principles, regardless of the moral aspects. Some are already performed in human society, others are common natural processes in natural animal populations.
Lawful birth control
Penalty for surplus offspring
In 1979 China introduced the One Child Policy, allowing only one child per couple. The results are not satisfying and it is highly controversial. One of the negative side effects is the growing imbalance of female and male babies.
Sterilization
This is a very common method for animals. It has been studied as a method for human birth control, but is unethical.
Education about birth control
In third world countries, where people are uneducated about birth control, populations are rising. In first world countries, where people are educated, populations are falling. Educating people about birth control will help limit the population. General education, in particular for women, has also been shown to reduce population growth. The very nature of a technological society may also limit birthrates, due to perceived economical disadvantage larger families may have in developed society.
Natural limitation
Limits to growth
Energetically, a population cannot grow beyond a certain size. The limit is reached with the equilibrium of the energy consumption of their member's metabolism and the energy contents of the available food. The limits of the system are variable, however. One of the reasons for a martian settlement is to open up the limits beyond the Earth and its surface.
Prey and predator equilibrium
As an example, if sharks became extinct, this would be a catastrophe for the ecological maritime system. Some herbivore fish would reproduce explosively, eating up certain plants and possibly starting a whole chain reaction of extinction for many species.
How a Martian colony might help solve Earth's overpopulation problem
Some people might think, we simply bring parts of the Earth's population to Mars, thus reducing the number of persons living from Earth's resources. Unfortunately, this does not work out, because the transportation effort and the kick-off support for the Martian colony consumes far more terrestrial resources than the resettled part of the population would ever use for a regular life on Earth.
But help could come from the economical principles of such a colony, which are fundamentally different from those or a terrestrial community. The Martian colony is bound to complete recycling and live with limited energy, and all this must function in a closed loop with little external resources. Efficient technologies need to be introduced to meet these requirements, and the experience with these technologies on Mars could be used by communities on Earth as well. The closed nature of the larger Earth ecosystems might become more obvious with the example of Mars. More efficient food production might allow for some population growth, while the underlying drivers for population growth are addressed by societies.
Access to the resources of space might open the loop on the terrestrial ecosystem, allowing more population growth. Alternatively, growth on Earth might stop, or even reverse itself, while growth in space became the new norm.
