Causes of overpopulation
From 1950 to 2011, world population increased from 2.5 billion to 7 billion and is forecast to reach a plateau of more than 9 billion by the middle of the 21st century. Recent forecasts place the possible number of people on the planet at 11 billion or 15 billion by 2100. Sir David King, former chief scientific adviser to the UK government, told a parliamentary inquiry: "It is self-evident that the massive growth in the human population through the 20th century has had more impact on biodiversity than any other single factor." At least until the middle of the 21st century, worldwide losses of pristine biodiverse land will probably depend much on the worldwide human birth rate.
Human population growth is one of the main drivers of species extinction.
According to a 2014 study by the World Wildlife Fund, the global human population already exceeds the planet's biocapacity - it would take the equivalent of 1.5 Earths of biocapacity to meet our current demands. The report further points out that if everyone on the planet had the footprint of the average resident of Qatar, we would need 4.8 Earths and if we lived the lifestyle of a typical resident of the USA, we would need 4 Earths.
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Causes of overpopulation: decline in the death rate
At the root of overpopulation is the mathematical dynamic between the overall birth rate and death rate in populations.
If the number of children born each year equals the number of adults that die, then the population will remain stable. Typically factors that increase the death rate tend to act over shorter periods of time, the ones that increase the birth rate tend to do so over longer periods of time.
Advancements in disease prevention, medical care, diet, health education, lifestyle and working conditions have contributed to the growing imbalance between birth and death rates. Current estimates suggest that every minute of every day, the net population grows by around 150 people.
Causes of overpopulation: better medical facilties
A few generations have made a world of difference. On average, a child born in the United States in 1900 would live to age 47. By 1965, life expectancy in the United States had increased to about 70 years. Infants born in the United States today can expect to live to age 80.
Better food and cleaner water have helped some. But the most important gains were in fighting diseases that were unrelated to water quality and malnutrition. Over the past century, life expectancy has been increasing primarily because of the development of effective medicines.
In the early part of the 20th century, the first 'battle' was won against infectious diseases such as tuberculosis, pneumonia, and typhoid fever. Deaths from these illnesses dropped rapidly, especially among children, and life expectancy increased as a result.
The effect of medical innovation is undeniable. By the 1960, deaths from infectious disease were no longer common. These illnesses were replaced by diabetes, heart disease, stroke, mental illness, and cancer as the greatest medical threats to life and well-being. Between 1950 and 1980, new medicines for all these diseases were introduced. Death rates declined and life expectancy grew.
Causes of overpopulation: advancement in fertility treatment
In 1934, a scientist at Harvard successfully conducted in-vitro fertilisation (IVF) experiments on rabbits – leading to the suggestion that the same procedure might be successful in humans. The scientist was quickly denounced for his “unethical” work and for “playing God”, but the idea was loose in the world, and couldn’t be stopped. IVF basically takes the natural fertilisation process outside of the human body.
Starting in the 1940s, IVF experiments began on humans, but researchers were timid in the face of public opposition, so the first successful embryos were never implanted in humans. Eventually, however, the first IVF baby, Louise Joy Brown, was born in England on July 25th, 1978. With the birth of this baby, which gave hope to millions of infertile couples, public opinion reversed almost overnight in favour of IVF.
In the few decades since the first successful IVF procedure, reproductive science has grown by leaps and bounds. Spurred by constant innovation, the rate of success for each individual IVF cycle has risen more than 20% points in the last 30 years. 30 years ago, the chance of a succesful outcome following a cycle of IVF treatment was 10%, now the chances have risen to over 30%.
In summary, IVF has provided an uplift to birth rates because couples who previously would not have been able to conceive are now able to do so.
Causes of overpopulation: agricultural advancements
From a historical perspective, technological revolutions have coincided with population explosions.
There have been three major technological revolutions – the tool-making revolution, the agricultural revolution, and the industrial revolution – all of which allowed humans more access to food, resulting in subsequent population explosions.
Agricultural advancements in the twentieth century on the back of scientific discovery have allowed humans to increase food production and yields further.
Fertilisers, herbicides, and pesticides have been used to increase land under cultivation as well as crop yields. Genetic engineering is now leading the vanguard of the latest wave of scientific advancements.
Other causes of overpopulation
Overpopulation can be considered at the global or local level. Taking a local view, looking at the net movement of people into or out of a region is important. Many people desire a move to developed countries like the U.S., U.K., Canada and Australia where the best opportunities are available in terms of medicine and healthcare provision, education provision, security and employment prospects.
Conflicts often lead to the displacement of large numbers of people who cross borders to find safety and security. Unfortunately, this often causes tension and further conflict between regional populations.
Family planning knowledge
Many developing nations have a large number of people who are illiterate, live below the poverty line and have little or no knowledge about family planning.
In this context, children often marry at an earlier age and start families at an earlier age increasing birth rates disproportionately.
There is a lack in education and knowledge surrounding the impacts of family planning choices and in many cases, religious or cultural pressures exacerbate the problem.