How Many People!?



Math 89SPopulation ScienceThe current state of population, the problems it creates, and the future of the worldTodd Iodice4-25-2016We’ve all waited in line for what seems like an eternity at the DMV, or struggled through traffic on a jam-packed highway, or gotten lost in a crowd at an amusement park. It’s terrible, waiting for a thousand other people to move so you can get where you’re going. When something like this happens, it seems that there’s just too many people in this world. But just how many of us are there? How did we get here and where are we going in terms of population? Are there consequences? These questions address a very real issue in the world today: population, overpopulation, and, in sense, the future of the human race.The Population SituationAccording to the World Population Clock, a real-time estimate of global population provided by the United States Census, the world is currently home to over 7.3 billion people, and that number is growing quickly (US Census). The Population Reference Bureau estimates that 143 million babies are born every year, but only 57 million people die, which, for those less numerically inclined, means the world’s population is growing by 86 million every year (PRB). That is a Rate of Natural Increase (birth rate – death rate) of about 1.2%.Why is this happening? Well, the biggest reason is a sharp decline in death rates over the last several hundred years, especially the child mortality rate. For much of human history, only about two children in every family survived to adulthood, which kept the population rather level (BBC). However, the eradication of many fatal diseases such as polio and smallpox as well as increased levels of hygiene and more advanced medical practice has ruptured this ‘equilibrium’. Between 1990 and 2012 alone, the child mortality rate, the number of deaths of children under 5 years old for every 1000 live births, plummeted from 90 to 48 (PRB). Also, the number of miscarriages and infant deaths has dropped to 38 for every 10,000 births, down from 80 in 1970. Moreover, total life expectancy has skyrocketed. Throughout the industrialized world, a baby born today can expect to live to over 80 years old, with Japan leading the pack at 83.7 years (WHO). Because of this uptick in longevity, an entire 7% of the world (500 million people) is over the age of 65 (PRB). These packs of old people were unfathomable for most of human history. For instance, life expectancy for a male born in the United Kingdom between 1276 and 3000 was only 31.3 years, but that number today is 81 (BBC, WHO). It is important to note, however, that much of the developing world falls well short of these numbers. The lowest life expectancy in the world is 46 years in Sierra Leone, and most of Africa fails to reach even 65 in this category (WHO).This gap brings up another element of the situation: the population and population growth are not evenly distributed. Of the 7.3 billion people, only 1.2 billion live in developed countries, which, by the UN definition, consist of all of Europe and North America as well as Australia, New Zealand, and Japan (PRB). Everyone else lives in the less-developed rest of the world. Moreover, of the 143 million births every year, 129 million occur in less developed countries. This gap is partially countered by an imbalance in death rates as those same countries experienced 45 million of the 57 million deaths. In fact, of the 5.5 million infant deaths every year, only 72,000 occur in the developed world, leaving a whopping 5.4 million to the less-developed (PRB). Thus, population growth is actually lower than its potential.Checks on PopulationWith so many people in the world and more coming in every second (4, to be exact, countered by only 2 deaths), many people have wondered what the limit is. After all, there is only so much space on Earth, so (barring inter-planetary migration) there must be a point at which the planet just can’t take any more people. Indeed, many great thinkers have explored the factors that limit human population, and the greatest of them all was the English clergyman-turned-economist Thomas Malthus.In “An Essay on the Principle of Population,” Malthus lays down his observations concerning human population growth. For him, the greatest limiting factor is food, for “population must always be kept down to the level of the means of subsistence” (Malthus vii). Malthus observed a disparity between the growth of food production and the growth of population: “Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetical ratio. A slight acquaintance with numbers will shew the immensity of the first power in comparison of the second” (4). Put simply, the power of humans to reproduce outweighs the power of the Earth to produce food. Humans, Malthus believed, would always have the same passion to reproduce, with the result that parents would have large number of children, who would each grow up and have a large number of children, and each of those children would have children of their own. Thus, Malthus estimated that, if there were no limiting factors present, the world population would double every twenty-five years for the rest of time (7).Food production, however, cannot double every twenty-five years, according to Malthus. It can increase at a steady, arithmetic rate, but this rate falls far short of the power of population growth, and this discrepancy creates limitations on the population that Malthus categorizes into two types of ‘checks’: preventative and positive. ‘Preventative checks’, according to Malthus, are the “foresight of the difficulties attending the rearing of a family” and include celibacy, contraception, and non-procreative sex (22). In essence, scarcity of resources entails much more labor on the part of the parents in raising children and often involves the parents sacrificing some of their own resources for the sake of their offspring. To prevent this, many people simply avoid having children when the population is pushing the limits of its food supply. Those who do have children subject them to ‘positive checks’, “by which they are disabled from giving the proper food and attention to their children” (22). When a population outgrows its food supply, disease, malnutrition, war, infanticide, and, most of all, famine reduce it back to the appropriate level. All of this keeps population far below its potential. According to modern calculations, Malthus was right. The rise in food production in the last 200 years has allowed for a drastic increase in population (see graph above), though far less than potential unchecked growth (Elwell). Population scientists today use two additional factors when determining population limits: water and energy. These work by the same preventative and positive checks as food (BCC). The LimitTaking these three factors into consideration, it is now possible to calculate exactly how many people this world can handle (under the present conditions of resource acquisition, which, of course, are liable to change). Unfortunately for humanity, we are already using most of the resources available to us. Although 70% of the Earth’s surface is covered in water, only 2% of it is fresh water (the kind we can drink), and only half of that isn’t frozen in glaciers or at the polar ice caps (BBC). We already use half of that remaining 1% of available water for all of our H2O needs, for the most part agriculture and industry. As a result, an entire 1.2 billion people lack access to reliable, clean water, and, according to Brian Richter of the Nature Conservancy, in the coming years more than half of the world’s population will live in areas of water stress (BBC). As for food, humanity already uses almost 40% of the Earth’s land surface for agriculture, and much of the rest is unsuitable for crops. The world managed to triple farming yields in the twentieth century thanks to the Green Revolution that spread modern farming techniques like fertilizer and pesticides across the globe, but these yields seem to have leveled off in recent years, meaning our food production is largely set at the moment (BBC). Finally, energy demand has increased 40% in the last two decades alone, with one big problem: there is a finite amount of fossil fuels in the ground. According to the Institute of Mechanical Engineers, only 1.3 trillion barrels of proven oil remain in the world’s major fields, which may seem like a lot, but if the world’s consumption remains constant at 85 million barrels a day, that amount should only last another 40 years or so (IBT, BBC).Taking these factors into consideration, human ecologist William Rees has calculated the “Productive Biocapacity of the Earth” (BBC). This value is made up all the food, water, and energy available for consumption and is measured in units called ‘global hectares’. At current rates of production, if these three resources were divided evenly across the world’s current population, each person would receive 2 hectares. These resources, however, are not distributed evenly, for industrialized countries use far more than their ‘fair share’ of 2 hectares each, while developing countries use far less (BBC). Thus, we can finally answer the question of how many people the Earth can sustain. At present levels of production, if everyone consumed the same as the average Indian, the Earth could handle 15 billion people. In fact, the Earth could support 18 billion humans who consumed as little as the average Rwandan does today. Nevertheless, that number drops to 2.5 billion at UK-level consumption. Finally, if everyone lived by the same lifestyle as we Americans do, the world could only sustain 1.5 billion people (BBC).Of course, as less-developed countries industrialize, their demand for these resources will only increase (IBD). This increased demand, along with our already-rising population, will bring us closer and closer to the world’s limit, with some catastrophic results. If we overshoot the Earth’s productive capacity, Malthus’ positive checks will come into play, and nobody wants the large amount of death and destruction that will ensue. We can try to extend production, for example by farming more land, but we must also consider the environmental impact of such actions. The massive increase in human population in recent years “has resulted in human beings exerting enormous aggregate pressure on the natural environment” (McMichael 1146). Indeed, population growth has had some truly devastating effects on the environment, including global climate change, stratospheric ozone depletion, accelerated loss of biodiversity, the spread of invasive species, land degradation, exhaustion of wild fisheries, depletion of freshwater supplies, and the long-distance dissemination and bioaccumulation of persistent organic chemicals (1146). In our drive to utilize the Earth, we have disturbed much of the natural order of things and left little room for anything else. Clearly, something must be done to prevent Malthus’ positive checks and yet at the same time protect the environment. SolutionsSome countries have instituted largescale, often controversial policies to try to stymie population growth. The most famous of these is China’s One Child Policy, which was implemented in response to decades of widespread famines and placed a hefty fine on families who produced more than one child (BBC). The policy has largely achieved its goals. China’s fertility rate, the average number of children born to a woman of child-bearing age, fell from 6.1 in in 1950 to 1.8 today (Sanyal). Without the policy, there would be almost 400 million more people in China today (BBC). Though there was public resistance to the policy, China’s authoritarian government allowed for its survival and implementation. The same could not be said for India in the 1970s. Seeing the negative effects of rapid population growth, the Indian government set up clinics around the country that paid male citizens to receive vasectomies (BBC). However, since the majority of those who participated were old and already had large families, in 1977 the government established mandatory vasectomies as punishment for every crime, leading to the forced sterilization of 8 million people. The public outcry against the policy was so great that it helped bring down the government (BBC). Clearly, not all government programs are so effective. Now, before you start the revolution for One Child Policies and other largescale government programs to save us from impending doom, there are some other, less invasive and far less controversial methods by which we can limit population growth. There are over 80 million unplanned births every year, in large part due to a lack of access to birth control. For instance, ? of married women in sub-Saharan Africa have no to access to any form of birth control (BBC). In fact, only 36% of married women of reproductive age use any form contraception in the world’s least developed countries, which include most of sub-Saharan Africa and portions of Asia (PRB). In the developed world, that rate rises to 70%. Moreover, the education of women actually contributes greatly to controlling population. Wherever women are well educated, they tend to marry later and choose to have smaller families (BBC). For instance, the population of the Indian state of Kerala is stable because nearly everybody has small families. The fertility rate there is only 1.5, and the average woman marries at the age of 28. These population limiters are largely attributed to its long history of compulsory education for both sexes that has given it one of the highest literacy rates in the world (BBC). Therefore, increasing access to birth control and expanding education for women could help promote those preventive checks admired by Malthus, without any governmental intrusion into peoples’ lives.Taking this a step further, many people believe we may not have to do anything at all. For instance, despite the failure of the government’s sterilization movement, India’s fertility rate in the last 60 years has fallen from 5.9 to 2.6, not too far above the replacement rate of 2.1, at which the population remains constant (Sanyal). This decline in growth is largely attributed to rapid urbanization and changing social attitudes. In fact, India’s growth is expected to fall further in the coming years due to a stark gender imbalance. For every 100 girls born in India, 110 boys are born (Sanyal). Such an imbalance also exists in China, where there are 118.6 boys born for every 100 girls. Thus, the Effective Fertility Rates (the fertility rate adjusted for gender imbalance) of India and China are only 2.45 and 1.5, respectively. As a result, despite recent moves to reduce and even eliminate the One Child Policy, the number of Chinese women of child-bearing age is expected to decrease by 18% over the next two decades, which will only further the decline. China’s overall population will continue to grow for the next couple decades due to increased longevity and immigration, but in the long term the effects will be population decline. As for India, it will soon pass China as the world’s most populous country, but its population is expected to stabilize at around 1.55 billion people in the early 2050s (PRB, Sanyal).As a matter of fact, simply allowing countries to grow economically may be enough to stymie population expansion. Trends around the world suggest that as countries get richer, their fertility rates and, by extension, their growth rates steadily fall (Economist). Ecologists identify two reproductive strategies inherent in animals. In the first strategy, known to ecologists as ‘r-selection’, parents produce lots of offspring but invest little in each individual child. This method works best in environments with high infant mortality, which, as shown above, clearly characterizes less developed nations. On the other hand, ‘K-selection’ involves having only a few offspring but nurturing them greatly so they become superb specimens and thereby have more success in the competition for resources and mates. Such a strategy is only possible for parents with sufficient resources. Thus, ecologists view the decreasing birth rates that come with industrialization as a shift from r-type to K-type behavior. A study conducted by Anna Goodman of the London School of Hygiene and Tropical Medicine, who gathered data on over 14,000 Swedish people born between 1915 and 1929 and their descendants, confirmed that the wealthy members of the population had fewer children, and this trend continued in the wealthy families even after four generations (Reardon). For this reason, many industrialized countries will actually shrink in population in the coming decades, including Germany, Japan, Russia, and much of Eastern Europe (BBC). In fact, the fertility rate of the Organization for Economic Cooperation and Development, a forum of the 34 most-developed economies in the world, has a combined fertility rate of only 1.74 (Sanyal). Clearly, industrialization can be part of the solution.ConclusionAlthough population growth will continue to decline in the coming decades, we still face some serious challenges as far as resources. Even low-ball estimates predict the world population will reach 9 to 10 billion by the end of the century before it levels off and perhaps even declines (Sanyal). To make matters worse, as less-developed countries continue to industrialize, their demand for resources will increase. Therefore, to compliment the fall in the rate of growth, we must continue to develop technology to increase our production of our three key resources (BBC). Renewable energy can certainly supply us past the eventual depletion of fossil fuels. Moreover, though at present, desalination plants are extremely expensive, require lots of energy, and often produce unfavorable byproducts, technological development to lessen these shortcomings can help provide the world with clean water. Finally, the industrialized world, especially the United States, must stop consuming so far beyond its share of resources (BBC). As discussed above, right now 5.5 billion people would have to die so that everyone could live like we do in the United States. We must make these changes for the good of the planet, to keep humanity from producing its own destruction.Works Cited“A Millennium of Health Improvement”. BBC. 27 December 1998. Print.Elwell, Frank W., 2003, "Malthus's?Population Principle Explained". How Many People Can Live on Planet Earth? Dir. Helen Shariatmadari. Perf. Sir David Attenborough. BBC, 2009. Film“How Much Oil is Left and How Long Will It Last?” International Business Times. 22 October 2014. Web.Life Expectancy at Birth. World Health Organization. Web.Malthus, Thomas. An Essay on the Principle of Population. London: J. Johnson, 1798. Print.McMichael, Anthony. “Population, environment, disease, and survival: past patterns, uncertain futures”. The Lancet 30 March 2002: 1145–1148. Print.“More or Less”. The Economist 1 September 2012. Print.Reardon, Sara. “Wealthy families obey economics rather than evolution”. New Scientist. 30 August 2012. Web.Sanyal, Sajeev. “The End of Population Growth”. Project Syndicate. 30 October 2011. Web.U.S. and World Population Clock. United States Census Bureau. Web.2014 World Population Data Sheet. Washington: Population Reference Bureau, 2014. Web.Images: ................
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