Human overpopulation (or human population overshoot ) is the idea 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.
124-459: Copenhagen Consensus is a project that seeks to establish priorities for advancing global welfare using methodologies based on the theory of welfare economics , using cost–benefit analysis . It was conceived and organized around 2004 by Bjørn Lomborg , the author of The Skeptical Environmentalist and the then director of the Danish government's Environmental Assessment Institute . The project
248-712: A 2017 paper that since the Second World War, countries with higher population growth rates experienced the most social conflict. Some advocates have suggested societal problems such as hunger and mass unemployment are linked to overpopulation. According to anthropologist Jason Hickel , the global capitalist system creates pressures for population growth : "more people means more labour, cheaper labour, and more consumers." He and his colleagues have also demonstrated that capitalist elites throughout recent history have "used pro-natalist state policies to prevent women from practicing family planning" in order to grow
372-588: A closed-door review of the background papers, each of the participants gave economic priority rankings to 17 of the proposals (the rest were deemed inconclusive). Below is a list of the 10 challenge areas and the author of the paper on each. Within each challenge, 3–4 opportunities (proposals) were analyzed: The panel agreed to rate seventeen of the thirty-two opportunities within seven of the ten challenges. The rated opportunities were further classified into four groups: Very Good, Good, Fair and Bad; all results are based using cost–benefit analysis. The highest priority
496-687: A combination of factors (including technological and social change) would allow global resources to meet this increased demand, avoiding global overpopulation. Additionally, some critics dismiss the idea of human overpopulation as a science myth connected to attempts to blame environmental issues on overpopulation, oversimplify complex social or economic systems, or place blame on developing countries and poor populations— reinscribing colonial or racist assumptions and leading to discriminatory policy. These critics often suggest overconsumption should be treated as an issue separate from population growth . World population has been rising continuously since
620-445: A competitive equilibrium for some set of prices. More generally, it suggests that redistribution should, if possible, be achieved without affecting prices (which should continue to reflect relative scarcity ), thus ensuring that the final (post-trade) result is efficient. Put into practice, such a policy might resemble predistribution . Because of welfare economics' close ties to social choice theory , Arrow's impossibility theorem
744-422: A competitive market equilibrium, provided that a social planner uses a social welfare function to choose the most equitable efficient outcome and then uses lump sum transfers followed by competitive trade to achieve it. Arrow's impossibility theorem which is closely related to social choice theory , is sometimes considered a third fundamental theorem of welfare economics. Welfare economics typically involves
868-400: A competitive market equilibrium. These restrictions are stronger than for the first fundamental theorem, with convexity of preferences and production functions a sufficient but not necessary condition. A direct consequence of the second theorem is that a benevolent social planner could use a system of lump sum transfers to ensure that the "best" Pareto efficient allocation was supported as
992-570: A consequence of overpopulation, according to the Food and Agriculture Organization , global food production exceeds increasing demand from global population growth. Food insecurity in some regions is attributable to the globally unequal distribution of food supplies. The notion that space is limited has been decried by skeptics, who point out that the Earth's population of roughly 6.8 billion people could comfortably be housed an area comparable in size to
1116-504: A diminished quality of human life. Ecologist David Pimentel was one such proponent, saying "with the imbalance growing between population numbers and vital life sustaining resources, humans must actively conserve cropland, freshwater, energy, and biological resources. There is a need to develop renewable energy resources. Humans everywhere must understand that rapid population growth damages the Earth's resources and diminishes human well-being." Although food shortages have been warned as
1240-452: A framework that ensures social integrity" to reduce the impact of "population growth on GHG emissions and biodiversity loss." In 2020, a quote from David Attenborough about how humans have "overrun the planet" was shared widely online and became his most popular comment on the internet. The World Wide Fund for Nature (WWF) and Global Footprint Network have argued that the annual biocapacity of Earth has exceeded, as measured using
1364-511: A global issue that some have linked to population growth. Colin Butler wrote in The Lancet in 1994 that overpopulation also has economic consequences for certain countries due to resource use. It was speculated by Aldous Huxley in 1958 that democracy is threatened by overpopulation, and could give rise to totalitarian style governments. Physics professor Albert Allen Bartlett at
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#17327974678651488-583: A higher rate than for any of the other 27 proposals, stating "so there is an obvious reason why the climate issue always is ranked last" in Lomborg's environmental studies. In a subsequent joint statement settling their differences, Lomborg and Yohe agreed that the "failure" of Lomborg's emissions reduction plan "could be traced to faulty design". In 2009, the Copenhagen convened an expert panel specifically to examine solutions to climate change. The process
1612-541: A justification". Cline responded to this by arguing that there is no obvious reason to use a large discount rate just because this is what is usually done in economic analysis. In other words, climate change ought to be treated differently from other, more imminent problems. The Economist quoted Mendelsohn as worrying that "climate change was set up to fail ". Moreover, Mendelsohn argued that Cline's damage estimates were excessive. Citing various recent articles, including some of his own, he stated that "[a] series of studies on
1736-512: A long history: Tertullian , a resident of the city of Carthage in the second century CE , criticized population at the time: "Our numbers are burdensome to the world, which can hardly support us... In very deed, pestilence, and famine, and wars, and earthquakes have to be regarded as a remedy for nations, as the means of pruning the luxuriance of the human race." Despite those concerns, scholars have not found historic societies that have collapsed because of overpopulation or overconsumption. By
1860-476: A measure would still be concerned with the distribution of income ( distributive efficiency ) but not the distribution of final utilities. In normative terms, such authors were writing in the Benthamite tradition. The ordinal-behaviorist approach, originally called the new welfare economics , is based on the work of Pareto , Kaldor , Hicks , and Scitovsky . It explicitly recognizes the differences between
1984-462: A migration project (guest-worker programmes for the unskilled), which was deemed to discourage integration; and three projects addressing climate change ( optimal carbon tax , the Kyoto Protocol and value-at-risk carbon tax ), which the panel judged to be least cost-efficient of the proposals. The panel found that all three climate policies presented have "costs that were likely to exceed
2108-531: A millionaire. At the other extreme is the Max-Min, or Rawlsian utility function. According to the Max-Min criterion, welfare is maximized when the utility of those society members that have the least is the greatest. No economic activity will increase social welfare unless it improves the position of the society member that is the worst off. Most economists specify social welfare functions that are intermediate between these two extremes. The social welfare function
2232-437: A number of conditions that can lead to inefficiency. They include: Note that if one of these conditions leads to inefficiency, another condition might help by counteracting it. For example, if a pollution externality leads to overproduction of tires, a tax on tires might restore the efficient level of production. A condition inefficient in the "first-best" might be desirable in the second-best . To determine whether an activity
2356-620: A number of periods of growth since the dawn of civilization in the Holocene period, around 10,000 BCE. The beginning of civilization roughly coincides with the receding of glacial ice following the end of the Last Glacial Period . Farming allowed for the growth of populations in many parts of the world, including Europe, the Americas and China through the 1600s, occasionally disrupted by plagues or other crises. For example,
2480-582: A population of six billion their biomass exceeded that of any other large land dwelling animal species that had ever existed by over 100 times. Inger Andersen , the executive director of the United Nations Environment Programme , stated in December 2022 as the human population reached a milestone of 8 billion and as delegates were meeting for the 2022 United Nations Biodiversity Conference , that "we need to understand that
2604-420: A social utility frontier represents an efficient allocation of an economy's resources; that is, it is a Pareto optimum in factor allocation, in production, in consumption, and in the interaction of production and consumption (supply and demand). In the diagram below, the curve MN is a social utility frontier. Point D corresponds with point C from the earlier diagram. Point D is on the social utility frontier because
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#17327974678652728-446: A true consensus, I think Lomborg would've had to invite ecologists, social scientists concerned with justice and how climate change impacts and policies are often inequitably distributed, philosophers who could challenge the economic paradigm of "one dollar, one vote" implicit in cost–benefit analyses promoted by economists, and climate scientists who could easily show that Lomborg's claim that climate change will have only minimal effects
2852-430: A valid concern, argue that increased levels of resource consumption and pollution exceed the environment's carrying capacity , leading to population overshoot . The population overshoot hypothesis is often discussed in relation to other population concerns such as population momentum , biodiversity loss , hunger and malnutrition , resource depletion , and the overall human impact on the environment . Critics of
2976-442: A vehicle, forgoing air travel, and adopting a plant-based diet . However, even in countries that have both large population growth and major ecological problems, it is not necessarily true that curbing the population growth will make a major contribution towards resolving all environmental problems that can be solved simply with an environmentalist policy approach. Continued population growth and overconsumption, particularly by
3100-664: Is "a primary driver behind many ecological and even societal threats." Ehlrich and other scientists at a conference in the Vatican on contemporary species extinction linked the issue to population growth in 2017, and advocated for human population control , which attracted controversy from the Catholic church . In 2019, a warning on climate change signed by 11,000 scientists from 153 nations said that human population growth adds 80 million humans annually, and "the world population must be stabilized—and, ideally, gradually reduced—within
3224-452: Is a curve that slopes downward to the right. The intermediate form of social indifference curve can be interpreted as showing that as inequality increases, a larger improvement in the utility of relatively rich individuals is needed to compensate for the loss in utility of relatively poor individuals. A crude social welfare function can be constructed by measuring the subjective dollar value of goods and services distributed to participants in
3348-530: Is a field of economics that applies microeconomic techniques to evaluate the overall well-being (welfare) of a society. The principles of welfare economics are often used to inform public economics , which focuses on the ways in which government intervention can improve social welfare . Additionally, welfare economics serves as the theoretical foundation for several instruments of public economics, such as cost–benefit analysis . The intersection of welfare economics and behavioral economics has given rise to
3472-457: Is a necessary, but not a sufficient condition for social welfare. Each Pareto optimum corresponds to a different income distribution in the economy. Some may involve great inequalities of income. So how do we decide which Pareto optimum is most desirable? This decision is made, either tacitly or overtly, when we specify the social welfare function . This function embodies value judgements about interpersonal utility. The social welfare function shows
3596-484: Is an efficiency goal that is standard in economics. A situation is Pareto-efficient only if no individual can be made better off without making someone else worse off. An example of an inefficient situation would be if Smith owns an apple but would prefer to consume an orange while Jones owns an orange but would be prefer to consume an apple. Both could be made better off by trading. A Pareto-efficient state of affairs can only come about if four criteria are met: There are
3720-531: Is delivered through the aggregate of individual preferences rather than the formation of government or income, especially those that exist because of neutrality, presented a challenge to reconcile conflicting interests in revenue sharing. The neutral results, avoiding special utility issues, restricted the social analyzes to structural utility issues. This restriction did not exclude important information about an individual’s social status or position needed to make an income allocation decision. Sen recommended expanding
3844-521: Is given an arbitrary budget constraint and instructed to use cost–benefit analysis to focus on a bottom line approach in solving/ranking presented problems. The approach is justified as a corrective to standard practice in international development , where, it is alleged, media attention and the "court of public opinion" results in priorities that are often far from optimal. The project has held conferences in 2004, 2007, 2008, 2009, 2011 and 2012. The 2012 conference ranked bundled micronutrient interventions
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3968-796: Is its effect on the environment. Some scientists suggest that the overall human impact on the environment during the Great Acceleration , particularly due to human population size and growth, economic growth , overconsumption, pollution , and proliferation of technology, has pushed the planet into a new geological epoch known as the Anthropocene . Biomass of mammals on Earth Some studies and commentary link population growth with climate change . Critics have stated that population growth alone may have less influence on climate change than other factors, such as greenhouse gas emissions per capita . The global consumption of meat
4092-520: Is known as Kaldor–Hicks efficiency . If the two conditions disagree, that yields the Scitovsky paradox . There are many combinations of consumer utility, production mixes, and factor input combinations consistent with efficiency. In fact, there are an infinity of consumption and production equilibria that yield Pareto optimal results. There are as many optima as there are points on the aggregate production–possibility frontier . Hence, Pareto efficiency
4216-484: Is maximized. Such point is called "the point of bliss". This point is Z where the social utility frontier MN is tangent to the highest possible social indifference curve labelled SI. Human overpopulation Since 1804, the global living human population has increased from 1 billion to 8 billion due to medical advancements and improved agricultural productivity . Annual world population growth peaked at 2.1% in 1968 and has since dropped to 1.1%. According to
4340-460: Is moving the economy towards Pareto efficiency, two compensation tests have been developed. Policy changes usually help some people while hurting others, so these tests ask what would happen if the winners were to compensate the losers. Using the Kaldor criterion , the change is desirable if the maximum amount the winners would be willing to pay is greater than the minimum the losers would accept. Under
4464-510: Is not sound science. Lomborg countered criticism of the panel membership by stating that "Sachs disparaged the Consensus 'dream team' because it only consisted of economists. But that was the very point of the project. Economists have expertise in economic prioritization. It is they and not climatologists or malaria experts who can prioritize between battling global warming or communicable disease". Welfare economics Welfare economics
4588-600: Is predicted that the population of sub-Saharan Africa will double by 2050. The Pew Research Center predicts that 50% of births in the year 2100 will be in Africa. As an example of uneven prospects, the UN projects that Nigeria will gain about 340 million people, about the present population of the US, to become the 3rd most populous country, and China will lose almost half of its population. Concerns about population size or density have
4712-511: Is projected to rise by as much as 76% by 2050 as the global population increases, with this projected to have further environmental impacts such as biodiversity loss and increased greenhouse gas emissions. A July 2017 study published in Environmental Research Letters argued that the most significant way individuals could mitigate their own carbon footprint is to have fewer children, followed by living without
4836-837: Is ranked well below other world problems. In 2011 the Copenhagen Consensus Center carried out the Rethink HIV project together with the RUSH Foundation, to find smart solutions to the problem of HIV/AIDS . In 2007 looked into which projects would contribute most to welfare in Copenhagen Consensus for Latin America in cooperation with the Inter-American Development Bank . The initial project was co-sponsored by
4960-657: Is run by the Copenhagen Consensus Center , which is directed by Lomborg and was part of the Copenhagen Business School , but it is now an independent 501(c)(3) non-profit organisation registered in the USA. The project considers possible solutions to a wide range of problems, presented by experts in each field. These are evaluated and ranked by a panel of economists. The emphasis is on rational prioritization by economic analysis. The panel
5084-405: Is sometimes listed as a third fundamental theorem. Utility functions can be derived from the points on a contract curve. Numerous utility functions can be derived, one for each point on the production possibility frontier (PQ in the diagram above). A social utility frontier (also called a grand utility frontier ) can be obtained from the outer envelope of all these utility functions. Each point on
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5208-428: Is there is zero bias in terms of preference between the present and the future generation (see time preference ). Moreover, Cline extended the time frame of the analysis to three hundred years in the future. Because the expected net damage of the global warming becomes more apparent beyond the present generation(s), this choice had the effect of increasing the present-value cost of the damage of global warming as well as
5332-531: Is therefore no surprise that the huge and complex challenge of long-term climate change was ranked last, and that scaling up health services in poor countries was ranked lower than interventions against specific diseases, despite warnings in the background papers that such interventions require broader improvements in health services." In response Lomborg argued that $ 50 billion was "an optimistic but realistic example of actual spending." "Experience shows that pledges and actual spending are two different things. In 1970
5456-456: Is thus a forced choice that bears no relationship to reality. No government is proposing that the marginal costs associated with, for example, an emissions trading system, should be deducted from its foreign aid budget. This way of posing the question is both morally inappropriate and irrelevant to the determination of real climate mitigation policy. Quiggin argued that the members of the 2004 panel, selected by Lomborg, were "generally towards
5580-438: Is typically translated into social indifference curves so that they can be used in the same graphic space as the other functions that they interact with. A utilitarian social indifference curve is linear and downward sloping to the right. The Max-Min social indifference curve takes the shape of two straight lines joined so as they form a 90-degree angle. A social indifference curve drawn from an intermediate social welfare function
5704-896: The American Association for the Advancement of Science were concerned about population growth. In 2017, more than one-third of 50 Nobel prize-winning scientists surveyed by the Times Higher Education at the Lindau Nobel Laureate Meetings said that human overpopulation and environmental degradation are the two greatest threats facing mankind. In November that same year, the World Scientists' Warning to Humanity: A Second Notice , signed by 15,364 scientists from 184 countries, indicated that rapid human population growth
5828-478: The COVID-19 pandemic that epidemics and pandemics were made more likely by overpopulation, globalization , urbanization and encroachment into natural habitats. They both play a significant role impacting human populations, including widespread illness , death , and social disruption . While they can leave a temporary loss of population, it is followed by significant loss and suffering. These events are not
5952-547: The Hicks criterion , the change is desirable if the maximum the losers would be willing to offer the winners to prevent the change is less than the minimum the winners would accept as a bribe to give up the change. The Hicks compensation test is from the losers' point of view; the Kaldor compensation test is from the winners'. If both conditions are satisfied, the proposed change will move the economy toward Pareto optimality. This idea
6076-480: The Pareto principle , totalitarianism , and free will Arrow concluded that there is no rational way to articulate individual preferences forms together resulting in a harmonious social status of the various social societies. Amartya Sen later emphasized the nature of the sequential gain approach, and Arrow's theory emphasized it. Sen said collective action often arises in social decision-making, because Arrow's theory
6200-575: The United Nations , eight billion as of November 2022. Some researchers have analyzed this growth in population like other animal populations, human populations predictably grow and shrink according to their available food supply as per the Lotka–Volterra equations , including agronomist and insect ecologist David Pimentel , behavioral scientist Russell Hopfenberg, and anthropologist Virginia Abernethy . World population has gone through
6324-506: The United Nations Population Division issued in 2022 (see chart) projects that global population will peak around the year 2086 at about 10.4 billion, and then start a slow decline (the median line on the chart). As with earlier projections, this version assumes that the global average fertility rate will continue to fall, but even further from 2.5 births per woman during the 2015–2020 period to 1.8 by
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#17327974678656448-562: The University of Colorado Boulder warned in 2000 that overpopulation and the development of technology are the two major causes of the diminution of democracy. However, over the last 200 years of population growth, the actual level of personal freedom has increased rather than declined. John Harte has argued population growth is a factor in numerous social issues, including unemployment , overcrowding , bad governance and decaying infrastructure. Daron Acemoglu and others suggested in
6572-516: The appropriateness of definitions being used (and often devolve into social scientists and biologists simply talking past each other ). Annual world population growth peaked at 2.1% in 1968, has since dropped to 1.1%, and could drop even further to 0.1% by 2100. Based on this, the United Nations projects the world population, which is 7.8 billion as of 2020 , to level out around 2100 at 10.9 billion with other models proposing similar stabilization before or after 2100. Some experts believe that
6696-454: The ecological footprint . In 2006, WWF's Living Planet Report stated that in order for all humans to live with the current consumption patterns of Europeans, we would be spending three times more than what the planet can renew. According to these calculations, humanity as a whole was using by 2006 40% more than what Earth can regenerate. Another study by the WWF in 2014 found that it would take
6820-561: The engineering of substitute goods and technology that better conserves and more efficiently uses natural resources, produces greater agricultural output with less land and less water, and addresses human impacts on the environment due to there being greater numbers of scientists, engineers, and inventors and subsequent generations of scientists overturning scientific paradigms maintained by previous generations of scientists . Instead, social scientists argue that disputes between themselves and biologists about human overpopulation are over
6944-458: The global south where most population growth happens. Modern proponents of the concept have suggested that overpopulation, population growth and overconsumption are interdependent and collectively are the primary drivers of human-caused environmental problems such as climate change and biodiversity loss . Many scientists have expressed concern about population growth, and argue that creating sustainable societies will require decreasing
7068-410: The 1930s and 40s, has largely collapsed since the discovery of Arrow's impossibility theorem and utility representation theorems have shown them to be mathematically self-contradictory , violating the principle of transitive preferences . Situations are considered to have distributive efficiency when goods are distributed to the people who can gain the most utility from them. Pareto efficiency
7192-469: The 20th century did not materialize. In The Population Bomb , Ehrlich stated, "In the 1970s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now," with later editions changing to "in the 1980s". Despite admitting some of his earlier predictions did not come to pass, Ehrlich continues to advocate that overpopulation is a major issue. As the profile of environmental issues facing humanity increased during
7316-551: The Black Death is thought to have reduced the world's population, then at an estimated 450 million in 1350, to between 350 and 375 million by 1400. After the start of the Industrial Revolution , during the 18th century, the rate of population growth began to increase. By the end of the century, the world's population was estimated at just under 1 billion. At the turn of the 20th century, the world's population
7440-405: The Copenhagen Consensus was asked to allocate an additional US$ 50 billion in spending by wealthy countries, distributed over five years, to address the world’s biggest problems. This was a poor basis for decision-making and for informing the public. By choosing such a low sum — a tiny fraction of global income — the project inherently favoured specific low-cost schemes over bolder, larger projects. It
7564-455: The Danish government and The Economist . A book summarizing the Copenhagen Consensus 2004 conclusions, Global Crises, Global Solutions , edited by Lomborg, was published in October 2004 by Cambridge University Press , followed by the second edition published in 2009 based on the 2008 conclusions. In May 2012, the third global Copenhagen Consensus was held, gathering economists to analyze
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#17327974678657688-399: The Earth , repudiated the entire approach of the project, arguing that applying cost–benefit analysis in the way the Copenhagen panel did was "junk economics". John Quiggin , an Australian economics professor, commented that the project is a mix of "a substantial contribution to our understanding of important issues facing the world" and an "exercises in political propaganda" and argued that
7812-404: The UN set itself the task of doubling development assistance. Since then the percentage has actually been dropping". "But even if Sachs or others could gather much more than $ 50 billion over the next 4 years, the Copenhagen Consensus priority list would still show us where it should be invested first." Thomas Schelling , one of the Copenhagen Consensus panel experts, later distanced himself from
7936-503: The authors of the global warming paper, subsequently accused Lomborg of "deliberate distortion of our conclusions", adding that "as one of the authors of the Copenhagen Consensus Project's principal climate paper, I can say with certainty that Lomborg is misrepresenting our findings thanks to a highly selective memory". Kåre Fog further pointed out that the future benefits of emissions reduction were discounted at
8060-528: The belief note that human population growth is decreasing and the population will likely peak, and possibly even begin to decrease, before the end of the century. They argue the concerns surrounding population growth are overstated, noting that quickly declining birth rates and technological innovation make it possible to sustain projected population sizes. Other critics claim that overpopulation concerns ignore more pressing issues, like poverty or overconsumption , are motivated by racism, or place an undue burden on
8184-545: The benefit of abatement policies. Members of the panel including Thomas Schelling and one of the two perspective paper writers Robert O. Mendelsohn (both opponents of the Kyoto protocol) criticised Cline, mainly on the issue of discount rates. (See "The opponent notes to the paper on Climate Change" ) Mendelsohn, in particular, characterizing Cline's position, said that "[i]f we use a large discount rate, they will be judged to be small effects" and called it "circular reasoning, not
8308-449: The benefits". It further stated "global warming must be addressed, but agreed that approaches based on too abrupt a shift toward lower emissions of carbon are needlessly expensive." In regard to the science of global warming, the paper presented by Cline relied primarily on the framework set by Intergovernmental Panel on Climate Change , and accepted the consensus view on global warming that greenhouse gas emissions from human activities are
8432-401: The coming decades, and advocated for policies to curb it. The Club of Rome published the influential report The Limits to Growth in 1972, which used computer modeling to similarly argue that continued population growth trends would lead to global system collapse. The idea of overpopulation was also a topic of some works of English-language science fiction and dystopian fiction during
8556-473: The costs and benefits of different approaches to tackling the world‘s biggest problems. The aim was to provide an answer to the question: If you had $ 75bn for worthwhile causes, where should you start? A panel including four Nobel laureates met in Copenhagen, Denmark, in May 2012. The panel’s deliberations were informed by thirty new economic research papers that were written just for the project by scholars from around
8680-777: The current global population. Advocates have suggested implementation of population planning strategies to reach a proposed sustainable population . Overpopulation hypotheses are controversial, with many demographers and environmentalists disputing the core premise that the world cannot sustain the current trajectory of human population. Additionally, many economists and historians have noted that sustained shortages and famines have historically been caused by war, price controls , political instability, and repressive political regimes (often employing central planning ) rather than overpopulation, and that population growth historically has led to greater technological development and advancement of scientific knowledge that has enabled
8804-535: The days of the Copenhagen Consensus 2012 conference, a series of articles was published in Slate Magazine each about a challenge that was discussed, and Slate readers could make their own ranking, voting for the solutions which they thought were best. Slate readers' ranking corresponded with that of the Expert Panel on many points, including the desirability of bundled micronutrient intervention; however,
8928-405: The derivation or assumption of a social welfare function , which can then be used to rank economically feasible allocations of resources based on the social welfare they generate. Until 1951, the objective of welfare economics remained largely uncontested. Economists viewed welfare economics as the branch of the discipline concerned with delineating the actions a governing body should undertake. It
9052-493: The early 19th century, intellectuals such as Thomas Malthus predicted that humankind would outgrow its available resources because a finite amount of land would be incapable of supporting a population with limitless potential for increase. During the 19th century, Malthus' work, particularly An Essay on the Principle of Population , was often interpreted in a way that blamed the poor alone for their condition and helping them
9176-457: The economy. The field of welfare economics is associated with two fundamental theorems. The first states that given certain assumptions, competitive markets (price equilibria with transfers, e.g. Walrasian equilibria ) produce Pareto efficient outcomes. The assumptions required are generally characterised as "very weak". More specifically, the existence of competitive equilibrium implies both price-taking behaviour and complete markets , but
9300-576: The efficiency aspect of the discipline and the distribution aspect and treats them differently. Questions of efficiency are assessed with criteria such as Pareto efficiency and Kaldor–Hicks efficiency , while questions of income distribution are covered in the specification of the social welfare function Further, efficiency dispenses with cardinal measures of utility, replacing it with ordinal utility , which merely ranks commodity bundles (with an indifference-curve map, for example). The consensus in favor of such approaches, pushed by behavioralists of
9424-478: The end of 2022. by UN in 2017 Population projections are attempts to show how the human population might change in the future. These projections help to forecast the population's impact on this planet and humanity's future well-being. Models of population growth take trends in human development , and apply projections into the future to understand how they will affect fertility and mortality , and thus population growth . The most recent report from
9548-568: The end of the Black Death , around the year 1350. The fastest doubling of the world population happened between 1950 and 1986: a doubling from 2.5 to 5 billion people in 37 years, mainly due to medical advancements and increases in agricultural productivity . Due to its impact on the human ability to grow food, the Haber process enabled the global population to increase from 1.6 billion in 1900 to 7.7 billion by November 2018 and, according to
9672-413: The end of the 20th and the early 21st centuries, some have looked to population growth as a root cause. In the 2000s, E. O. Wilson and Ron Nielsen discussed overpopulation as a threat to the quality of human life. In 2011, Pentti Linkola argued that human overpopulation represents a threat to Earth's biosphere . A 2015 survey from Pew Research Center reports that 82% of scientists associated with
9796-513: The environment and accompanying increase in resource consumption threatens the world's ecosystems and the survival of human civilization. The InterAcademy Panel Statement on Population Growth , which was ratified by 58 member national academies in 1994, states that "unprecedented" population growth aggravates many environmental problems, including rising levels of atmospheric carbon dioxide , global warming , and pollution. Indeed, some analysts claim that overpopulation's most serious impact
9920-595: The equivalent of 1.5 Earths of bio-capacity to meet humanity's current levels of consumption. However, Roger Martin of Population Matters states the view: "the poor want to get rich, and I want them to get rich," with a later addition, "of course we have to change consumption habits,... but we've also got to stabilize our numbers". Critics have questioned the simplifications and statistical methods used in calculating ecological footprints. Therefore, Global Footprint Network and its partner organizations have engaged with national governments and international agencies to test
10044-474: The global human population," sustainability can be achieved more rapidly with a short term focus on technological and social innovations, along with reducing consumption rates, while treating population planning as a long-term goal. However, most scientists believe that achieving genuine sustainability is a long-term project, and that addressing population and consumption levels are both essential to achieving it. In 1992, more than 1700 scientists from around
10168-430: The growth of the human population caused encroachment in wild habitats which have led to their destruction, "posing a potential threat to biodiversity components". Some scientists and environmentalists, including Jared Diamond , E. O. Wilson , Jane Goodall and David Attenborough , contend that population growth is devastating to biodiversity . Wilson for example, has expressed concern when Homo sapiens reached
10292-419: The highest priority, and the 2008 report identified supplementing vitamins for undernourished children as the world’s best investment. The 2009 conference, dealing specifically with global warming , proposed research into marine cloud whitening (ships spraying seawater into clouds to make them reflect more sunlight and thereby reduce temperature) as the top climate change priority, though climate change itself
10416-413: The impacts of climate change have systematically shown that the older literature overestimated climate damages by failing to allow for adaptation and for climate benefits." The 2004 Copenhagen Consensus attracted various criticisms: The 2004 report, especially its conclusion regarding climate change, was subsequently criticised from a variety of perspectives. The general approach adopted to set priorities
10540-519: The latter part of the 1960s. The United Nations held the first of three World Population Conferences in 1974. Human population and family planning policies were adopted by some nations in the late 20th century in an effort to curb population growth, including in China and India . Albert Allen Bartlett gave more than 1,742 lectures on the threat of exponential population growth starting in 1969. However, many predictions of overpopulation during
10664-525: The marginal rate of substitution at point C is equal to the marginal rate of transformation at point A. Point E corresponds with point B in the previous diagram, and lies inside the social utility frontier (indicating inefficiency) because the MRS at point C is not equal to the MRT at point A. Although all the points on the grand social utility frontier are Pareto efficient, only one point identifies where social welfare
10788-606: The more people there are, the more we put the Earth under heavy pressure. As far as biodiversity is concerned, we are at war with [the rest of] nature." Human overpopulation and continued population growth are also considered by some, including animal rights attorney Doris Lin and philosopher Steven Best , to be an animal rights issue, as more human activity means the destruction of animal habitats and more direct killing of animals. Some commentary has attributed depletion of non-renewable resources , such as land , food and water , to overpopulation and suggested it could lead to
10912-409: The most common estimate was 8 billion. Advocates of reduced population often put forward much lower numbers. Paul R. Ehrlich stated in 2018 that the optimum population is between 1.5 and 2 billion. In 2022 Ehrlich and other contributors to the "Scientists' warning on population", including Eileen Crist, William J. Ripple , William E. Rees and Christopher Wolf, stated that environmental analysts put
11036-441: The most recent United Nations' projections , the global human population is expected to reach 9.7 billion in 2050 and would peak at around 10.4 billion people in the 2080s, before decreasing, noting that fertility rates are falling worldwide. Other models agree that the population will stabilize before or after 2100. Conversely, other researchers have found that national birth registries data from 2022 and 2023 that cover half
11160-548: The most striking difference was in connection with the problem of overpopulation . Family planning ranked highest on the Slate priority list, whereas it didn't feature in the top 16 of the Expert Panel's prioritisation. Nobel Prize winners marked with (¤) In the Copenhagen Consensus 2008, the solutions for global problems have been ranked in the following order: Unlike the 2004 results, these were not grouped into qualitative bands such as Good, Poor, etc. Gary Yohe , one of
11284-586: The only additional assumption is the local non-satiation of agents' preferences – that consumers would like, at the margin, to have slightly more of any given good. The first fundamental theorem is said to capture the logic of Adam Smith's invisible hand , though in general there is no reason to suppose that the "best" Pareto efficient point (of which there are a set) will be selected by the market without intervention, only that some such point will be. The second fundamental theorem states that given further restrictions, any Pareto efficient outcome can be supported as
11408-429: The primary cause of the global warming. Cline relies on various research studies published in the field of economics and attempted to compare the estimated cost of mitigation policies against the expected reduction in the damage of the global warming. Cline used a discount rate of 1.5%. (Cline's summary is on the project webpage ) He justified his choice of discount rate on the ground of "utility-based discounting", that
11532-400: The process of reducing the total numbers. They suggested several possible approaches, including: There is good evidence from many parts of the world that when women and couples have the freedom to choose how many children to have, they tend to have smaller families. Some scientists, such as Corey Bradshaw and Barry Brook, suggest that, given the "inexorable demographic momentum of
11656-427: The relative importance of the individuals that comprise society. A utilitarian welfare function (also called a Benthamite welfare function) sums the utility of each individual in order to obtain society's overall welfare. All people are treated the same, regardless of their initial level of utility. One extra unit of utility for a starving person is not seen to be of any greater value than an extra unit of utility for
11780-499: The results list, partly because they would take a long time to have much effect on temperatures. Eight economists met May 24–28, 2004 at a roundtable in Copenhagen . A series of background papers had been prepared in advance to summarize the current knowledge about the welfare economics of 32 proposals ("opportunities") from 10 categories ("challenges"). For each category, one assessment article and two critiques were produced. After
11904-552: The results—reviews have been produced by France, Germany, the European Commission, Switzerland, Luxembourg, Japan and the United Arab Emirates . Some point out that a more refined method of assessing Ecological Footprint is to designate sustainable versus non-sustainable categories of consumption. Attempts have been made to estimate the world's carrying capacity for humans; the maximum population
12028-458: The right and, to the extent that they had stated views, to be opponents of Kyoto." Sachs also noted that the panel members had not previously been much involved in issues of development economics and were unlikely to reach useful conclusions in the time available to them. Commenting on the 2004 Copenhagen Consensus, climatologist and IPCC author Stephen Schneider criticised Lomborg for only inviting economists to participate: In order to achieve
12152-420: The scope of data used in welfare research and emphasized the need for explicit discussion of ethics and morality in welfare economics. The early Neoclassical approach was developed by Edgeworth , Sidgwick , Marshall , and Pigou . It assumes the following: With these assumptions, it is possible to construct a social welfare function simply by summing all the individual utility functions. Note that such
12276-468: The selection of the panel members was slanted towards the conclusions previously supported by Lomborg. Quiggin observed that Lomborg had argued in his controversial book The Skeptical Environmentalist that resources allocated to mitigating global warming would be better spent on improving water quality and sanitation, and was therefore seen as having prejudged the issues. Under the heading "Wrong Question", Sachs further argued that: "The panel that drew up
12400-453: The size of their workforce. Hickel has however argued that the cause of negative environmental impacts is resource extraction by wealthy countries. He concludes that "we should not ignore the relationship between population growth and ecology, but we must not treat these as operating in a social and political vacuum." A 2021 article in Ethics, Medicine and Public Health argued in light of
12524-408: The sole reason for overpopulation, but lack of access to family planning and reproductive contraptions, poverty and resource depletion . Several strategies have been proposed to mitigate overpopulation. Several scientists (including Paul Ehrlich , Gretchen Daily and Tim Flannery ) proposed that humanity should work at stabilizing its absolute numbers, as a starting point towards beginning
12648-495: The state of Texas in the United States (about 269,000 square miles or 696,706.80 square kilometres). Critics and agricultural experts suggest changes to policies relating to land use or agriculture to make them more efficient would be more likely to resolve land issues and pressures on the environment than focusing on reducing population alone. Water scarcity , which threatens agricultural productivity, represents
12772-403: The subfield of behavioral welfare economics. Two fundamental theorems are associated with welfare economics. The first states that competitive markets, under certain assumptions, lead to Pareto efficient outcomes. This idea is sometimes referred to as Adam Smith's invisible hand . The second theorem states that with further restrictions, any Pareto efficient outcome can be achieved through
12896-452: The sustainable level of human population at between 2 and 4 billion people. Geographer Chris Tucker estimates that 3 billion is a sustainable number. Although proponents of human overpopulation have expressed concern that growing population will lead to an increase in global poverty and infant mortality , both indicators have declined over the last 200 years of population growth. A number of scientists have argued that human impacts on
13020-578: The underlying social welfare function. By postulating W as W(UA, UB) and assuming W to be a positive function of each individual's utility, it was shown that maximum welfare occurred when allocative efficiency was achieved, and the marginal contribution to welfare of each individual was equalized. But this decision did not last long. In 1951, Kenneth Arrow tested whether rational collective selection rules could derive social welfare functions from individuals in preference to social states. He argued that rational law satisfies four conditions: partial universality,
13144-402: The way in which the Consensus results have been interpreted in the wider debate, arguing that it was misleading to put climate change at the bottom of the priority list. The Consensus panel members were presented with a dramatic proposal for handling climate change. If given the opportunity, Schelling would have put a more modest proposal higher on the list. The Yale economist Robert O. Mendelsohn
13268-429: The wealthy, have been posited as key drivers of biodiversity loss and contemporary species extinction , with some researchers and environmentalists specifically suggesting this indicates a human overpopulation scenario. The Global Assessment Report on Biodiversity and Ecosystem Services , released by IPBES in 2019, states that human population growth is a factor in biodiversity loss. IGI Global has uncovered
13392-520: The world can host. 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 98 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". A 2012 United Nations report summarized 65 different estimated maximum sustainable population sizes and
13516-503: The world signed onto a " World Scientists' Warning to Humanity ," including a majority of the living Nobel prize-winners in the sciences. "The earth is finite," they wrote. "Its ability to absorb wastes and destructive effluent is finite. Its ability to provide food and energy is finite. Its ability to provide for growing numbers of people is finite. And we are fast approaching many of the earth's limits." The warning noted: Pressures resulting from unrestrained population growth put demands on
13640-492: The world's population indicate that the 2022 UN projections overestimated fertility rates by 10 to 20% and are already outdated, that the global fertility rate has possibly already fallen below the sub-replacement fertility level for the first time in human history, and that the global population will peak at approximately 9.5 billion by 2061. The 2024 UN projections report estimated that world population would peak at 10.29 billion in 2084 and decline to 10.18 billion by 2100, which
13764-522: The world. The panel members were the following, four of whom are Nobel Laureate economists . In addition, the Center commissioned research on Corruption and trade barriers , but the Expert Panel did not rank these for Copenhagen Consensus 2012, because the solutions to these challenges are political rather than investment-related. Given the budget restraints, they found 16 investments worthy of investment (in descending order of desirability): During
13888-440: The year 2100. However, other estimates predict additional downward pressure on fertility (such as more education and family planning) which could result in peak population during the 2060–2070 period rather than later. According to the UN, of the predicted growth in world population between 2020 and 2050, all of that change will come from less developed countries , and more than half will come from just 8 African countries. It
14012-515: Was 6% lower than the UN had estimated in 2014. Early discussions of overpopulation in English were spurred by the work of Thomas Malthus . Discussions of overpopulation follow a similar line of inquiry as Malthusianism and its Malthusian catastrophe , a hypothetical event where population exceeds agricultural capacity, causing famine or war over resources, resulting in poverty and depopulation. More recent discussion of overpopulation
14136-413: Was assigned to implementing certain new measures to prevent the spread of HIV and AIDS . The economists estimated that an investment of $ 27 billion could avert nearly 30 million new infections by 2010. Policies to reduce malnutrition and hunger were chosen as the second priority. Increasing the availability of micronutrients , particularly reducing iron deficiency anemia through dietary supplements ,
14260-559: Was commonly accepted that the term "maximizing welfare" held a specific meaning rooted in the philosophical framework of utilitarianism. Within the profession, there was ongoing debate regarding whether utility was an ordinal or cardinal concept. This debate seemed to have been addressed by Abram Bergson 's seminal paper in 1938, "A Reformulation of Certain Aspects of Welfare Economics." Bergson demonstrated that economic efficiency conditions could be precisely formulated without fully specifying
14384-429: Was criticised by Jeffrey Sachs , an American economist and advocate of both the Kyoto protocol and increased development aid, who argued that the analytical framework was inappropriate and biased and that the project "failed to mobilize an expert group that could credibly identify and communicate a true consensus of expert knowledge on the range of issues under consideration.". Tom Burke, a former director of Friends of
14508-421: Was increased spending on research into new agricultural technologies appropriate for developing nations. Three proposals for improving sanitation and water quality for a billion of the world’s poorest followed in priority (ranked sixth to eighth: small-scale water technology for livelihoods, community-managed water supply and sanitation, and research on water productivity in food production). Completing this group
14632-517: Was judged to have an exceptionally high ratio of benefits to costs, which were estimated at $ 12 billion. Third on the list was trade liberalization ; the experts agreed that modest costs could yield large benefits for the world as a whole and for developing nations . The fourth priority identified was controlling and treating malaria ; $ 13 billion costs were judged to produce very good benefits, particularly if applied toward chemically-treated mosquito netting for beds. The fifth priority identified
14756-474: Was popularized by Paul Ehrlich in his 1968 book The Population Bomb and subsequent writings. Ehrlich described overpopulation as a function of overconsumption , arguing that overpopulation should be defined by a population being unable to sustain itself without depleting non-renewable resources . The belief that global population levels will become too large to sustain is a point of contentious debate. Those who believe global human overpopulation to be
14880-704: Was roughly 1.6 billion. By 1940, this figure had increased to 2.3 billion. Even more dramatic growth beginning in 1950 (above 1.8% per year) coincided with greatly increased food production as a result of the industrialization of agriculture brought about by the Green Revolution . The rate of human population growth peaked in 1964, at about 2.1% per year. Recent additions of a billion humans happened very quickly: 33 years to reach three billion in 1960, 14 years for four billion in 1974, 13 years for five billion in 1987, 12 years for six billion in 1999, 11 years for seven billion in 2010, and 12 years for 8 billion toward
15004-819: Was said to worsen conditions in the long run. This resulted, for example, in the English poor laws of 1834 and a hesitating response to the Irish Great Famine of 1845–52. The first World Population Conference was held in 1927 in Geneva, organized by the League of Nations and Margaret Sanger . Paul R. Ehrlich 's book The Population Bomb became a bestseller upon its release in 1968 and created renewed interest in overpopulation. The book predicted population growth would lead to famine , societal collapse , and other social, environmental and economic strife in
15128-504: Was similar to the 2004 and 2008 Copenhagen Consensus, involving papers by specialists considered by a panel of economists. The panel ranked 15 solutions, of which the top 5 were: The benefits of the number 1 solution are that if the research proved successful this solution could be deployed relatively cheaply and quickly. Potential problems include environmental impacts e.g. from changing rainfall patterns. Measures to cut carbon and methane emissions , such as carbon taxes , came bottom of
15252-454: Was the 'government' project concerned with lowering the cost of starting new businesses. Ranked tenth was the project on lowering barriers to migration for skilled workers . Eleventh and twelfth on the list were malnutrition projects – improving infant and child nutrition and reducing the prevalence of low birth weight . Ranked thirteenth was the plan for scaled-up basic health services to fight diseases. Ranked fourteenth to seventeenth were:
15376-413: Was the official critic of the proposal for climate change during the Consensus. He thought the proposal was way out of the mainstream and could only be rejected. Mendelsohn worries that climate change was set up to fail. Michael Grubb, an economist and lead author for several IPCC reports, commented on the Copenhagen Consensus, writing: To try and define climate policy as a trade-off against foreign aid
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