Written by Sam Wallace - City of London Freemens School
The global population is constantly growing, however in the recent century it has grown exponentially, this rapid growth of the population has caused a huge rise in debate over what the optimum population should be, to stop or most probably try to slow down the effects of climate change and the related crisis in the world today. The current global population stands at 8,115,896,159 as of Sunday 16th 2024, and this number rises roughly 10,000 people an hour, this poses huge problems for the world, with usable living space becoming extremely scarcer due to extreme weather events increasing in frequency and in effect.
There are many different arguments from many different experts who have varying answers to the question. Paul Ehrlich an American biologist in 2018 said “ the optimum global population was between 1.5 and 2 billion people.” Another view from American Geography Chris Tucker who stated that with sufficient changes and checks within societies 3 billion would be a sustainable number for population. Many people put numbers on and estimate the optimum population, however I feel this is incredibly hard to do and even harder to do accurately. Many theories suggest different opinions on population growth, let alone the optimum or when it ‘should’ stop.
Figure 1 - iStock
Thomas Malthus an English economist created his theory in 1798 of Malthusian economics, he stated then that Population grows exponentially, this theory also suggested that food production cannot keep up with population growth, as it grows in linear pattern, this posed large problems when published in his 1798 essay as it showed very early that Population growth was and will be out of hand. Although this ‘Malthusian Catastrophe’ has not occurred in our history, it may yet take place. On the contrary, Paul Ehrlich predicted in his 1968 book ‘The Population Bomb’ that there would be mass starvation due to overpopulation in countries such as India and Egypt in the 1970s. He said that these countries were ‘hopeless’ cases and thus there was nothing to be done to prevent this crisis so humanitarian aid was useless. He was entirely incorrect: for example, India continued to receive food aid from countries such as the US and Canada. The ‘Green Revolution’ originally fathered by Norman Borlaug, an agricultural scientist, was able in the 1960’s with funding from the Ford Foundation and the Rockefeller Foundation to create New technologically advanced crops. The Green Revolution happened earliest in Mexico and challenged areas in USA, but quickly migrated across the world in the 1970’s and 80’s, reaching Philippines and India, this included mechanization of cultivation, and new crop and agricultural technology. HYV’s ( high yielding variety crops ) were invented to improve resistance to disease, and increase food production yields, widespread use of chemical fertilizer and irrigation methods were adopted. India managed to overcome the crisis due to these technological innovation like HYV crops, these types of crops and these technological advancement and innovations are clear evidence to disprove Theories from Ehrlich and Malthus as it shows that even with the population growing Food security can still grow at a similar rate as population growth. Another population theorists Esther Boserup said in 1965, “ necessity is the mother of innovation”, This statement disagrees with Malthus and Ehrlich and the theories given by Boserup are correct to disprove the earlier theories proposed. She is right to say that We as humans will always find a way to facilitate the needs of the population. This can be said, however it is only true to a certain extent, as previously seen with innovation such as the green revolution, humans will find a way to innovate and technologically advance But Could there be a point where we are unable to keep up with the growing population with new advancements, at this point could we see a Malthusian Catastrophe, following the J curve model.
Figure 2 - J Curve Model
The model shows the natural carrying capacity of the earth and its resources. As population rises, and at the speed it is happening right now at a 0.9% annual increase it’s clear to see we are fast approaching the point of maximum capacity. This is backed up by the UN estimates that by 2086 population will peak at around 10.4 billion, this estimate is down to factors of natural population decline, where birth rate will be below death rate, however this could happen for numerous reasons. The most common reason is that the global population will start to age by the 2080’s, and with the social norms ever changing the need for children will decline, with more Women now working longer hours, higher paying higher responsibility roles, and with less household and agricultural jobs needing children to run, the fertility rate globally has fallen rapidly since the 1960’s, and in many high income countries ( HIC’s) fertility rate has even dropped below the replacement rate of 2.1, this shows the effect of ageing population and a natural decline, with the population of Japan, South Korea and Germany notably all now in decline.
Even though many HIC’s experience this there are many low-income countries ( LIC’s) which also experience population decline, but not a natural decrease. There are many countries experiencing population troubles, these countries may still have rapidly growing populations, but they are constantly experiencing shocks, which now happen more frequently. These shocks are ones such as the Sahel Famine of 2010, where the region spanning East to West of Africa just south of the Saharan desert experienced the worst famine in up to 70 years, with new temperature record set in multiple countries in the belt, Sudan being one where the temperature reached 50 degrees. Many have put the 2010 famine, and famines that followed in 2011 and 2012 in Africa and other across the world down to a cause of overpopulation in less developed countries. These countries are not only LIC’s, but are also countries with non-preferable growing climates, this means that the land being overused to try and feed the growing population is hardly arable enough to feed it’s carrying capacity let alone some 5 to 10 times above the carrying capacity of the land. The famine in 2010 led to 250,000 people dying of malnutrition and starvation and 1,200,000 people facing extreme risk of famine, and a third of the livestock in the area dying. Famines and droughts are becoming more common due to over-population and the pressure that the rapid growth puts on the sustainability of our actions. These increased extreme weather events, whether they are droughts and famines in Africa, or heavy rain and flooding have large social and economic impact, not only are hundreds of thousands of people displaced and affected by these events with houses destroyed or land degraded, but also there are detrimental economic effects, local economies that rely on the output of local farms and businesses in these areas may collapse and certain worldwide trades may hit downturns, the overpopulation and its subsequent effects in one country can lead to huge trickle down effects across the world. The impacts cause techniques to be adopted to combat the issues that think about the now and not the future, which greatly reduces our own sustainability and has enormous knock-on effects for the future generations, this shows the magnitude of the problem we have facing us due to the current overpopulation issue and worries about further overpopulation in the future.
Another shock experienced in many Countries across the world is overcrowding and subsequent decline in air quality and health, with some places In India having 32 times worse air quality than the WHO’s acceptable level. With increasing Populations there is greater pollution, as more energy is needed to cook or to heat, and more fuel will be needed for more people to get to work, this increase in energy at the moment is unrenewable energy usage, which contributes greatly to climate change and global warming, showing huge costly and damaging effects that current growing population has on the world right now, and this is only likely to increase. This has been predicted by many Geographers and sustainable developers, many say that the change to a greener and more sustainable world happened too late, saying ‘ we’ve gone past the point of no return’. Once again, these detrimental impacts that rise from rapid population increase have vast social and economic impacts. Socially and economically many people lose their lives due to pollution and poor health and hygiene standards around the world, especially seen in LIC’s with any Hospitals overworked, such as the Kiagware hospital in Kenya which is the ‘local’ hospital for over 500,000 patients, with minimal staff, problems like this show that socially there are too many people in these areas, and economically there’s not enough infrastructure or investment. Not every person has access to clean and healthy water or proper hygiene standards or health checks that we can have available at almost any time in a country like the UK. In 2023, Only 61% of households in Tanzania currently have access to a basic water-supply, 32% have access to basic sanitation, and 48% have access to basic hygiene, according to SDG definitions. This is mainly down to the overpopulation of these areas that cannot adapt to the rapid growth; therefore people end up in overcrowded unhygienic spaces, greatly increasing their risk of disease and death, an externality.
Figure 3 - iStock
With a larger and larger proportion of people with a greater risk of death and disease and more and more people becoming susceptible to climate change it is clear to see the current number and the current rate of increase is past where the optimum point is for Global Population.
Although theories from Boserup are currently correct, that human population will always adapt and that ‘ necessity is the mother of innovation’, the green revolution and solutions to previous large scale population scares through famines etc, clearly show she was right to a certain extent that Humans will always find a way to fight for their existence, and we can largely disprove the Malthusian theory as food production has clearly increased at a non-linear rate and kept up with population growth, Boserup’s theory doesn’t factor in the effects that this innovation or these adaptions might have on the world as an ecosystem and the environmental effects sustained.
In conclusion, many theorists have tried to create an accurate estimate and pinpoint the number at which they think the optimum global population is. However, I believe after reviewing these theories and other external environmental, social and economic factors in the world, it is extremely difficult to create an exact number. I agree that the current population is too high, and the rate of growth has been substantially higher than it should have been for the last 100-200 years, This means it is difficult to estimate the optimum population, as you could have one billion or 8 billion people, but depending on the way these people act and the goodness of their actions, it is impossible to judge at what point there is an optimum for global population. The optimum is most likely to be lower than the current population today, however you could argue that without the vast size of todays population certain findings and innovations would not have happened possibly leading to the breakdown of Mankind as it is today if the population wasn’t so large. Both sides of the argument can be argued with positives and negatives to a large or a small population, however my overall conclusion is that the size of the population isn’t what affects the optimum level, I believe it is the way that the population acts - in their own self-interest or in the interest of preserving the world with environmentally correct decisions, that has more of an effect on the optimum level of population, at what point do people start acting out of their own self-interests, that is the point at which the optimum population is passed.
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