Sustainable population

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Sustainable population refers to a proposed sustainable human population of Earth or a particular region of Earth, such as a nation or continent. Estimates vary widely, with estimates based on different figures ranging from 0.65 billion people to 9.8 billion, with 8 billion people being a typical estimate. Projections of population growth, evaluations of overconsumption and associated human pressures on the environment have led to some to advocate for what they consider a sustainable population. Proposed policy solutions vary, including sustainable development, female education, family planning and broad human population planning.

Contents

Emerging economies like those of China and India aspire to the living standards of the Western world, as does the non-industrialized world in general. [1] As of 2022, China and India account for most of the population in Asia, with more than 1.4 billion each. [2] It is the combination of population increase in the developing world and unsustainable consumption levels in the developed world that poses a stark challenge to sustainability. [3]

According to the UN Population Fund, high fertility and poverty have been strongly correlated, and the world's poorest countries also have the highest fertility and population growth rates. [4]

Estimates

World population growth rate, 1950-2050, as estimated in 2011 by the U.S. Census Bureau, International Data Base. Although the rate of growth decreases, population continues to rise. In 2050 still growing by over 45 million per year WorldPopGrowth.png
World population growth rate, 1950–2050, as estimated in 2011 by the U.S. Census Bureau, International Data Base. Although the rate of growth decreases, population continues to rise. In 2050 still growing by over 45 million per year
Map of countries and territories by fertility rate as of 2020 Total Fertility Rate Map by Country.svg
Map of countries and territories by fertility rate as of 2020

Sustainable population

Many studies have tried to estimate the world's sustainable population for humans, that is, the maximum population the world can host. [5] A 2004 meta-analysis of 69 such studies from 1694 until 2001 found the average predicted maximum number of people the Earth would ever have was 7.7 billion people, with lower and upper meta-bounds at 0.65 and 9.8 billion people, respectively. They conclude: "recent predictions of stabilized world population levels for 2050 exceed several of our meta-estimates of a world population limit". [6] A 2012 United Nations report summarized 65 different estimates of maximum sustainable population size and the most common estimate was 8 billion. [7] [8]

Climate change, excess nutrient loading (particularly nitrogen and phosphorus), increased ocean acidity, rapid biodiversity loss, and other global trends suggest humanity is causing global ecological degradation and threatening ecosystem services that human societies depend on. [9] [10] [11] Because these environmental impacts are all directly related to human numbers, recent estimates of a sustainable human population tend to put forward much lower numbers, between 2 and 4 billion. [12] [13] [14] Paul R. Ehrlich stated in 2018 that the optimum population is between 1.5 and 2 billion. [15] Geographer Chris Tucker estimates that 3 billion is a sustainable number, provided human societies rapidly deploy less harmful technologies and best management practices. [16] Other estimates of a sustainable global population also come in at considerably less than the current population of 8 billion. [17] [18] [19]

A 2014 study published in the Proceedings of the National Academy of Sciences of the United States of America posits that, given the "inexorable demographic momentum of the global human population," efforts to slow population growth in the short term will have little impact on sustainability, which can be more rapidly achieved with a focus on technological and social innovations, along with reducing consumption rates, while treating population planning as a long term goal. The study says that with a fertility-reduction model of one-child per female by 2100, it would take at least 140 years to reduce the population to 2 billion people by 2153. [20] [21] The 2022 "Scientists' warning on population," published by Science of the Total Environment , states that "environmental analysts regard a sustainable human population as one enjoying a modest, equitable middle-class standard of living on a planet retaining its biodiversity and with climate-related adversities minimized," which is estimated at between 2 and 4 billion people. [22]

Skeptics criticize the basic assumptions associated with these overpopulation estimates. For example, Jade Sasser believes that calculating a maximum of number of humanity which may be allowed to live while only some, mostly privileged European former colonial powers, are mostly responsible for unsustainably using up the Earth, is wrong. [23]

But if current human numbers are not ecologically sustainable, the costs are likely to fall on the world’s poorest citizens, regardless of whether they helped cause the problem. [24] [25] In fact, countries that contribute the most to unsustainable production and consumption practices often have higher income per capita and slower population growth, unlike countries that have a low income per capita and rapidly growing populations. [26]

According to a 2022 study published in Sustainable Development, a sustainable population is required for both preserving biodiversity and food security. The study says that falling fertility rates are linked to access to contraception and family planning services, and has little to no relation to economic growth. [27]

World population

According to data from 2015, the world population is projected to reach 8.5 billion by 2030, up from the current 8 billion, to exceed 9 billion people by 2050, and to reach 11.2 billion by the year 2100. [28] Most of the increase will be in developing countries whose population is projected to rise from 5.6 billion in 2009 to 7.9 billion in 2050. This increase will be distributed among the population aged 15–59 (1.2 billion) and 60 or over (1.1 billion) because the number of children under age 15 in developing countries is predicted to decrease. In contrast, the population of the more developed regions is expected to undergo only slight increase from 1.23 billion to 1.28 billion, and this would have declined to 1.15 billion but for a projected net migration from developing to developed countries, which is expected to average 2.4 million persons annually from 2009 to 2050. [29] Long-term estimates in 2004 of global population suggest a peak at around 2070 of nine to ten billion people, and then a slow decrease to 8.4 billion by 2100. [30]

However, these projections assume substantial improvements in contraceptive availability throughout the developing world and large decreases in desired family size (particularly in sub-Saharan Africa), which may or may not happen. [31] In the end, all population projections must be taken with a large pinch of salt. [32] Particular care is needed to remember that future population size will depend on policy decisions and individual choices. [33]

Carrying capacity

Urbanization in Seattle, Washington, United States Seattle from Beacon Hill.jpg
Urbanization in Seattle, Washington, United States

Talk of economic and population growth overshooting the limits of Earth's carrying capacity for humans is popular in environmentalism. [34] The potential limiting factor for the human population might include water availability, energy availability, renewable resources, non-renewable resources, heat removal, photosynthetic capacity, or land availability for food production. [35] Or, as current trends suggest, the limiting factors might involve ecosystems’ ability to absorb human pollution, as with climate change, ocean acidification, or the toxification of rivers and streams. [36] [11] [37] The applicability of carrying capacity as a measurement of the Earth's limits in terms of the human population has been questioned, since it has proved difficult to calculate or predict the upper limits of population growth. [34] Carrying capacity has been used as a tool in Neo-Malthusian arguments to limit population growth since the 1950s. [38] The concept of carrying capacity has been applied to determining the population limits in Shanghai, a city faced with rapid urbanization. [39]

The application of the concept of carrying capacity for the human population, which exists in a non-equilibrium, has been criticized for not successfully being able to model the processes between humans and the environment. [34] [40] In popular discourse the concept is often used vaguely in the sense of a "balance between nature and human populations". [40]

In human ecology a popular definition from 1949 states "the maximum number of people that a given land area will maintain in perpetuity under a given system of usage without land degradation setting in". Sociologists have criticized this for numerous reasons. Aside from the fact that humans are able to adopt new customs and technology, some common critiques are 1.) an assumption an equilibrium population exists, 2.) difficulties in measuring resources, 3.) inability to account for human tastes and how much labour they will expend, 4.) assumption of full usage of resources, 5.) assumption of landscape homogeneity, 6.) assumption that regions are isolated from each other, 7.) contradicted by history, and 8.) the standard of living is ignored. [40]

Romanian American economist Nicholas Georgescu-Roegen, a progenitor in economics and a paradigm founder of ecological economics, has argued in 1971 that the carrying capacity of Earth — that is, Earth's capacity to sustain human populations and consumption levels — is bound to decrease sometime in the future as Earth's finite stock of mineral resources is presently being extracted and put to use. [41] : 303  Leading ecological economist and steady-state theorist Herman Daly, a student of Georgescu-Roegen, has propounded the same argument. [42] : 369–371  In a series of writings, Daly has explored the connection between limiting population and achieving ecologically sustainable societies, arguing that a sustainable economy must involve limits to human numbers, since per capita human resource use can never be driven down to zero. [43] [44]

See also

Related Research Articles

<span class="mw-page-title-main">Sustainable development</span> Mode of human development

Sustainable development is an organizing principle that aims to meet human development goals while also enabling natural systems to provide necessary natural resources and ecosystem services to humans. The desired result is a society where living conditions and resources meet human needs without undermining the planetary integrity and stability of the natural system. Sustainable development tries to find a balance between economic development, environmental protection, and social well-being. The Brundtland Report in 1987 defined sustainable development as "development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs". The concept of sustainable development nowadays has a focus on economic development, social development and environmental protection for future generations.

The carrying capacity of an environment is the maximum population size of a biological species that can be sustained by that specific environment, given the food, habitat, water, and other resources available. The carrying capacity is defined as the environment's maximal load, which in population ecology corresponds to the population equilibrium, when the number of deaths in a population equals the number of births. The effect of carrying capacity on population dynamics is modelled with a logistic function. Carrying capacity is applied to the maximum population an environment can support in ecology, agriculture and fisheries. The term carrying capacity has been applied to a few different processes in the past before finally being applied to population limits in the 1950s. The notion of carrying capacity for humans is covered by the notion of sustainable population.

<span class="mw-page-title-main">Agricultural productivity</span> Quotient between production and productive factors

Agricultural productivity is measured as the ratio of agricultural outputs to inputs. While individual products are usually measured by weight, which is known as crop yield, varying products make measuring overall agricultural output difficult. Therefore, agricultural productivity is usually measured as the market value of the final output. This productivity can be compared to many different types of inputs such as labour or land. Such comparisons are called partial measures of productivity.

Overconsumption describes a situation where a consumer overuses their available goods and services to where they can't, or don't want to, replenish or reuse them. In microeconomics, this may be described as the point where the marginal cost of a consumer is greater than their marginal utility. The term overconsumption is quite controversial in use and does not necessarily have a single unifying definition. When used to refer to natural resources to the point where the environment is negatively affected, it is synonymous with the term overexploitation. However, when used in the broader economic sense, overconsumption can refer to all types of goods and services, including manmade ones, e.g. "the overconsumption of alcohol can lead to alcohol poisoning". Overconsumption is driven by several factors of the current global economy, including forces like consumerism, planned obsolescence, economic materialism, and other unsustainable business models and can be contrasted with sustainable consumption.

The ecological footprint measures human demand on natural capital, i.e. the quantity of nature it takes to support people and their economies. It tracks human demand on nature through an ecological accounting system. The accounts contrast the biologically productive area people use to satisfy their consumption to the biologically productive area available within a region, nation, or the world (biocapacity). Biocapacity is the productive area that can regenerate what people demand from nature. Therefore, the metric is a measure of human impact on the environment. As Ecological Footprint accounts measure to what extent human activities operate within the means of our planet, they are a central metric for sustainability.

<span class="mw-page-title-main">Environmental degradation</span> Any change or disturbance to the environment perceived to be deleterious or undesirable

Environmental degradation is the deterioration of the environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defined as any change or disturbance to the environment perceived to be deleterious or undesirable. The environmental degradation process amplifies the impact of environmental issues which leave lasting impacts on the environment.

<span class="mw-page-title-main">Land degradation</span> Gradual destruction of land

Land degradation is a process in which the value of the biophysical environment also biochemical environment is affected by a combination of human-induced processes acting upon the land. It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable. Natural hazards are excluded as a cause; however human activities can indirectly affect phenomena such as floods and bush fires.

<span class="mw-page-title-main">Steady-state economy</span> Constant capital and population size

A steady-state economy is an economy made up of a constant stock of physical wealth (capital) and a constant population size. In effect, such an economy does not grow in the course of time. The term usually refers to the national economy of a particular country, but it is also applicable to the economic system of a city, a region, or the entire world. Early in the history of economic thought, classical economist Adam Smith of the 18th century developed the concept of a stationary state of an economy: Smith believed that any national economy in the world would sooner or later settle in a final state of stationarity.

The "World Scientists' Warning to Humanity" was a document written in 1992 by Henry W. Kendall and signed by about 1,700 leading scientists. Twenty-five years later, in November 2017, 15,364 scientists signed "World Scientists' Warning to Humanity: A Second Notice" written by William J. Ripple and seven co-authors calling for, among other things, human population planning, and drastically diminishing per capita consumption of fossil fuels, meat, and other resources. The second notice has more scientist cosigners and formal supporters than any other journal article ever published.

<span class="mw-page-title-main">William E. Rees</span>

William Rees, FRSC, is Professor Emeritus at the University of British Columbia and former director of the School of Community and Regional Planning (SCARP) at UBC.

Human overpopulation describes a concern that human populations may become too large to be sustained by their environment or resources in the long term. The topic is usually discussed in the context of world population, though it may concern individual nations, regions, and cities.

<span class="mw-page-title-main">Ecological resilience</span> Capacity of ecosystems to resist and recover from change

In ecology, resilience is the capacity of an ecosystem to respond to a perturbation or disturbance by resisting damage and subsequently recovering. Such perturbations and disturbances can include stochastic events such as fires, flooding, windstorms, insect population explosions, and human activities such as deforestation, fracking of the ground for oil extraction, pesticide sprayed in soil, and the introduction of exotic plant or animal species. Disturbances of sufficient magnitude or duration can profoundly affect an ecosystem and may force an ecosystem to reach a threshold beyond which a different regime of processes and structures predominates. When such thresholds are associated with a critical or bifurcation point, these regime shifts may also be referred to as critical transitions.

Degrowth is an academic and social movement critical of the concept of growth in gross domestic product as a measure of human and economic development. Degrowth theory is based on ideas and research from a multitude of disciplines such as economics, economic anthropology, ecological economics, environmental sciences and development studies. It argues that the unitary focus of modern capitalism on growth, in terms of monetary value of aggregate goods and services, causes widespread ecological damage and is not necessary for the further increase of human living standards. Degrowth theory has been met with both academic acclaim and considerable criticism.

<span class="mw-page-title-main">Sustainability</span> Goal of people safely co-existing on Earth

Sustainability is a social goal for people to co-exist on Earth over a long time. Definitions of this term are disputed and have varied with literature, context, and time. Experts often describe sustainability as having three dimensions : environmental, economic, and social, and many publications emphasize the environmental dimension. In everyday use, sustainability often focuses on countering major environmental problems, including climate change, loss of biodiversity, loss of ecosystem services, land degradation, and air and water pollution. The idea of sustainability can guide decisions at the global, national, and individual levels. A related concept is sustainable development, and the terms are often used to mean the same thing. UNESCO distinguishes the two like this: "Sustainability is often thought of as a long-term goal, while sustainable development refers to the many processes and pathways to achieve it."

Overpopulation or overabundance is a phenomenon in which a species' population becomes larger than the carrying capacity of its environment. This may be caused by increased birth rates, lowered mortality rates, reduced predation or large scale migration, leading to an overabundant species and other animals in the ecosystem competing for food, space, and resources. The animals in an overpopulated area may then be forced to migrate to areas not typically inhabited, or die off without access to necessary resources.

In environmental science, a population "overshoots" its local carrying capacity — the capacity of the biome to feed and sustain that population — when that population has not only begun to outstrip its food supply in excess of regeneration, but actually shot past that point, setting up a potentially catastrophic crash of that feeder population once its food populations have been consumed completely. Overshoot can apply to human overpopulation as well as other animal populations: any life-form that consumes others to sustain itself.

<span class="mw-page-title-main">Earth Overshoot Day</span> Calculated calendar date when humanitys yearly consumption exceeds Earths replenishment

Earth Overshoot Day (EOD) is the calculated illustrative calendar date on which humanity's resource consumption for the year exceeds Earth’s capacity to regenerate those resources that year. The term "overshoot" represents the level by which human population's demand overshoots the sustainable amount of biological resources regenerated on Earth. When viewed through an economic perspective, the annual EOD represents the day by which the planet's annual regenerative budget is spent, and humanity enters environmental deficit spending. EOD is calculated by dividing the world biocapacity, by the world ecological footprint, and multiplying by 365, the number of days in a year:

<span class="mw-page-title-main">History of environmental pollution</span>

The history of environmental pollution traces human-dominated ecological systems from the earliest civilizations to the present day. This history is characterized by the increased regional success of a particular society, followed by crises that were either resolved, producing sustainability, or not, leading to decline. In early human history, the use of fire and desire for specific foods may have altered the natural composition of plant and animal communities. Between 8,000 and 12,000 years ago, agrarian communities emerged which depended largely on their environment and the creation of a "structure of permanence."

The biocapacity or biological capacity of an ecosystem is an estimate of its production of certain biological materials such as natural resources, and its absorption and filtering of other materials such as carbon dioxide from the atmosphere.

<span class="mw-page-title-main">Ecological overshoot</span> Demands on ecosystem exceeding regeneration

Ecological overshoot is the phenomenon which occurs when the demands made on a natural ecosystem exceed its regenerative capacity. Global ecological overshoot occurs when the demands made by humanity exceed what the biosphere of Earth can provide through its capacity for renewal.

References

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