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.
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.
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.
Energetically, a population can not 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.
Scientists found out that if the sharks in the sea become extinct, this will be a catastrophe for the ecological maritime system. Some herbivore fish would reproduce explosively, eating up certain plants, starting a whole chain reaction of extinction of many species.
How a Martian colony can help solving 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 salvation could come from the economical principles of such a colony, which are fundamentally different from the terrestrial. The Martian colony is bound to complete recycling and live with extremely limited energy, and all this must function in a local site. Special technology needs to be introduced to meet these requirements, and the experience with this technology on Mars can be used by communities on Earth, as well. This way, the officials on Earth will hopefully gain an environmental awareness and learn how to live in a balanced way on it's own resources.