While population growth is at times a beneficial thing for a species, there are many factors that define when growth becomes detrimental. When population growth becomes “rapid” there is a great chance that the counter-productive level has been reached. The most accurate index is the balance between population and sustainability.
Rapid growth is a quick increase in population. The number concerned when calculating the population is the number of individuals alive. In other words, while some areas may have large numbers of births, they may not realize an increase in their population if the death rate is sufficient to offset the birthrate. These sort of factors can actually contribute to birth rates and the rate of growth. For example, in times when populations have experienced great losses, a rapid increase in population may occur. In these situations this may be termed a “correction” (this is a statistical concept). The “Baby Boom” following World War II is an instance of this sort.
There can be a variety of causes for rapid population growth. There are circumstances which can create sentiment in the population that will inspire population growth. These are usually immediate, or short lived, occurrences and can cause rapid growth. There are also other conditions which seem inversely related. In areas of poverty and lower living conditions, birth rates are sometimes higher. This can result in birth rates higher than those of industrialized nations where birth control is ubiquitous and pregnancy is put off for some time. Another cause of population growth is older populations living longer while birth rates do not decline. Many nations are experiencing rapid population growth of that sort in numbers that haven't existed in the past. Any combination or single factor can cause the population number to increase in the immediate, but some factors are more likely to cause sustained growth.
Population growth, even rapid population growth, can be a positive thing. Examples include corrections when the rapid growth may actually supply a population that wouldn't have existed to contribute otherwise. With sustained growth and rapid growth though there is a risk of overpopulation. When the level of overpopulation is reached, a number of negative effects can occur and a number of startling correlations are being discovered. Among the most definite and devastating effects of overpopulation is lack of land. The lack of land results in a number of things which result in negative impact on the population. Waste management of such populations is also difficult to handle effectively and can result in pollution and detriment to the environment. Without adequate land per individual the quality of housing decreases. Another result is insufficient land to produce crops. This results in hunger and ultimately starvation. These can be catastrophic and cause repercussions in the process. One example of these problems was London after the Industrial Revolution. Because of the population explosion in London, living space was minimal, leading to overcrowded conditions. A lack of food caused malnutrition, and poor waste management led to contaminated water supplies, which caused high levels of disease, such as typhoid and cholera.
Changes in population sentiment
A newer correlation that has only recently been adequately studied to comment on is the effects on social stability of overpopulation. While it may seem evident that starvation may cause discontent, scientific studies have recently shown correlation between overpopulation and civil unrest. In many areas of unstable populations higher numbers of civil conflict within the area exist. Correlations like these often risk being self-sustaining and can spiral.
No single action is effective against all instances of rapid population or overpopulation. Some instances of rapid population growth may be a healthy response to some new factor. Monitoring populations and helping with the individual causes of unhealthy rapid population growth may help to prevent sustained overpopulation.