This article has multiple issues. Please help improve it or discuss these issues on the talk page . (Learn how and when to remove these messages)
|
Paul R. Ehrlich | |
---|---|
Born | Paul Ralph Ehrlich May 29, 1932 |
Education | |
Known for | The Population Bomb (1968) Simon–Ehrlich wager |
Spouse | |
Children | 1 |
Awards |
|
Scientific career | |
Fields | |
Institutions | Stanford University |
Thesis | The Morphology, Phylogeny and Higher Classification of the Butterflies (Lepidoptera: Papilionoidea) (1957) |
Doctoral advisor | C. D. Michener |
Paul Ralph Ehrlich (born May 29, 1932) is an American biologist known for his predictions and warnings about the consequences of population growth, including famine and resource depletion. [2] [3] [4] [5] Ehrlich is the Bing Professor Emeritus of Population Studies of the Department of Biology of Stanford University.
Ehrlich became well known for the controversial 1968 book The Population Bomb, which he co-authored with his wife Anne H. Ehrlich, in which they famously stated that "[i]n the 1970s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now." [6] [7] Among the solutions suggested in that book was population control, including "various forms of coercion" such as eliminating "tax benefits for having additional children". [2]
Scholars, journalists and public intellectuals have mixed views on Ehrlich's assertions on the dangers of expanding human populations. [8] While Paul A. Murtaugh, associate professor of statistics at Oregon State University, says that Ehrlich was largely correct, [9] Ehrlich has been criticized for his approach and views, both for their pessimistic outlook and, later on, for the repeated failure of his predictions to come true. In response to Ehrlich's assertion that all major marine wildlife would die by 1980, Ronald Bailey termed Ehrlich an "irrepressible doomster". [10] Ehrlich has acknowledged that "some" of what he predicted has not occurred, but nevertheless maintains that his predictions about disease and climate change were essentially correct and that human overpopulation is a major problem. [11] Whereas American journalist Jonathan V. Last has called The Population Bomb "one of the most spectacularly foolish books ever published", [12] journalist Fred Pearce argues that overconsumption is the real problem. [13]
Ehrlich was born in Philadelphia, Pennsylvania, the son of William Ehrlich and Ruth Rosenberg. His father was a shirt salesman (unrelated to the German scientist Paul Ehrlich), his mother a Greek and Latin scholar [14] and public school teacher. [6] Ehrlich's mother's Reform-Jewish German ancestors arrived in the United States in the 1840s, and his paternal grandparents emigrated there later from the Galician and Transylvanian part of the Austrian Empire. [15] During his childhood his family moved to Maplewood, New Jersey, where he attended Columbia High School, graduating in 1949. [6] [16]
By training, Ehrlich is an entomologist specializing in Lepidoptera (butterflies). He earned a bachelor's degree in zoology from the University of Pennsylvania in 1953, an M.A. from the University of Kansas in 1955, and a Ph.D. from the University of Kansas in 1957, supervised by the prominent bee researcher Charles Duncan Michener (the title of his dissertation: "The Morphology, Phylogeny and Higher Classification of the Butterflies (Lepidoptera: Papilionoidea)"). [17] During his studies he participated with surveys of insects in the areas of the Bering Sea and Canadian arctic, and then with a National Institutes of Health fellowship, investigated the genetics and behavior of parasitic mites. In 1959 he joined the faculty at Stanford University. He became well-known for popularizing the term coevolution in an influential 1964 paper co-authored with the botanist Peter H. Raven, where they proposed that an evolutionary 'arms-race' between plants and insects explains the extreme diversification of plants and insects. [18] This paper was highly influential on the then-nascent field of chemical ecology. He was promoted to professor of biology in 1966, and appointed to the Bing Professorship in 1977. [19] [20] In 1984, he founded the Center for Conservation Biology at Stanford University. [21] He is a fellow of the American Association for the Advancement of Science, the United States National Academy of Sciences, the American Academy of Arts and Sciences and the American Philosophical Society. [19]
A lecture that Ehrlich gave on the topic of overpopulation at the Commonwealth Club of California was broadcast by radio in April 1967. [22] The success of the lecture caused further publicity, and the suggestion from David Brower the executive director of the environmentalist Sierra Club, and Ian Ballantine of Ballantine Books to write a book concerning the topic. Ehrlich and his wife, Anne H. Ehrlich, collaborated on the book, The Population Bomb , but the publisher insisted that a single author be credited; only Paul's name appears as an author. [23]
Although Ehrlich was not the first to warn about population issues — concern had been widespread during the 1950s and 1960s — his charismatic and media-savvy methods helped publicize the topic. [24] The Tonight Show Starring Johnny Carson had Ehrlich on as a guest more than twenty times, with one interview lasting an hour. [25] [26]
The original edition of The Population Bomb began with the statement:
The battle to feed all of humanity is over. In the 1970s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now. At this late date nothing can prevent a substantial increase in the world death rate ... [27]
Ehrlich argued that the human population was too great, and that while the extent of disaster could be mitigated, humanity could not prevent severe famines, the spread of disease, social unrest, and other negative consequences of overpopulation.
Ehrlich has proposed different solutions to the problem of overpopulation. In The Population Bomb he wrote, "We must have population control at home, hopefully through a system of incentives and penalties, but by compulsion if voluntary methods fail. We must use our political power to push other countries into programs which combine agricultural development and population control." [27] Voluntary measures he has endorsed include the easiest possible availability of birth control and abortion. In 1967, he went so far as to insist that countries such as India be allowed to starve, while aid would only be given to those countries that were not considered to be "hopeless". [28]
Decades later, Ehrlich's continued prominence and the failure of the book's predictions to materialize led to renewed scrutiny and criticism. The New York Times said his "apocalyptic predictions fell as flat as ancient theories about the shape of the Earth". [2]
Science author Charles C. Mann wrote that the book's predictions "fueled an anti-population-growth crusade that led to human rights abuses around the world", including coercive population control policies and even forced sterilizations. [29] Ehrlich's pointed criticism of India in particular (for instance, emphasizing the overpopulation of Delhi rather than Paris, which had nearly triple Delhi's population at the time of writing) has been criticized for focusing much more on "feelings" than on actual data. [29]
Neither of the Ehrlichs have ever publicly renounced predictions, instead insisting that they were largely correct, despite the errors noted by many experts.[ dubious – discuss ] [30]
The Population Explosion argues that the population catastrophe outlined in the Ehrlichs' earlier work The Population Bomb had in fact come to pass, and that "hunger is rife and famine and plague ever more imminent". [31]
Many accepted the premise of a looming population problem, with the New York Times writing that "it is not merely prudent but imperative that we confront population issues, and do so now". [32] Notwithstanding this wide agreement, the Ehrlichs were criticized for an "alarmist" tone. [33] The book was also criticised for its approach to family planning, arguing against increased family planning efforts aimed at empowering individuals and families. [34] The Ehrlichs were accused of advocating the curtailment of reproductive freedoms and giving the state a larger role in such decisions, while leaving ambiguous "just how authoritarian a solution they are willing to endorse." [33]
Subsequent attention to the book scrutinized its descriptions of an unfolding overpopulation catastrophe. The book's contention that global food production had already peaked proved to be incorrect. [35] Similarly, the prediction that India faced catastrophic food shortage in the 1990s failed to materialize. [35]
In this paper, the Ehrlichs discussed their opinion on the 'optimal size' for human population, given their assessment of the current technological situation. They referred to establishing "social policies to influence fertility rates." [36]
During a 2004 interview, Ehrlich answered questions about the predictions he made in The Population Bomb. He acknowledged that some of what he had published had not occurred, but stated that he felt "little embarrassment" and reaffirmed his basic opinion that overpopulation is a major problem. He noted that, "Fifty-eight academies of science said that same thing in 1994, as did the world scientists' warning to humanity in the same year. My view has become depressingly mainline!" [11] Ehrlich also asserted that 600 million people were very hungry while billions were under-nourished, and falsely insisted that his predictions about disease and climate change were essentially correct. [11] Retrospectively, Ehrlich said that The Population Bomb, which predicted a widespread famine by 1985 that never materialized, was actually "way too optimistic". [22] [23]
In a 2008 discussion hosted by the website Salon, Paul Ehrlich was more critical of the United States specifically, claiming that it should control its population and consumption as an example to the rest of the world. He still professed a belief that governments should discourage people from having more than two children, suggesting, for example, a higher tax rate for larger families. [37]
In 2011, as the world's population passed the seven billion mark, Ehrlich argued that the next two billion people on Earth would cause more damage than the previous two billion, as humans now increasingly would have to resort to using more marginal and environmentally damaging resources. [38] As of 2013, Ehrlich continued to perform policy research concerning population and resource issues, with an emphasis upon endangered species, cultural evolution, environmental ethics, and the preservation of genetic resources. Along with Dr. Gretchen Daily, he performed work in countryside biogeography; that is, the study of making human-disturbed areas hospitable to biodiversity. His research group at Stanford University examined extensive natural populations of the Bay checkerspot butterfly (Euphydryas editha bayensis). [39]
The population-related disaster that Ehrlich predicted has failed to materialize, including the "hundreds of millions" of starvation deaths in the 1970s and the tens of millions of deaths in the United States in the 1970s and 1980s. Slowing of population growth rates and new food production technologies have increased the food supply faster than the population. [2] Nonetheless, Ehrlich continues to stand by his general thesis that the human population is too large, posing a direct threat to human survival and the environment of the planet. Indeed, he states that if he were to write the book today, "My language would be even more apocalyptic." [2] In 2018, he emphasized his view that the optimum population size is between 1.5 and 2 billion people. [40] In 2022, he was a contributor to the "Scientists' warning on population," published by Science of the Total Environment , which estimated that a sustainable population would be between 2 and 4 billion people. [41]
Critics have disputed Ehrlich's main thesis about overpopulation and its effects on the environment and human society, and his solutions, as well as some of his specific predictions made since the late 1960s. A common criticism concerns Ehrlich's alarmist and sensational statements and inaccurate predictions, leading economist Thomas Sowell to call out Ehrlich as being "consistently wrong on so many things". [42] Ronald Bailey of Reason magazine has termed him an "irrepressible doomster ... who, as far as I can tell, has never been right in any of his forecasts of imminent catastrophe." [10] On the first Earth Day in 1970, he warned that "[i]n ten years all important animal life in the sea will be extinct. Large areas of coastline will have to be evacuated because of the stench of dead fish." [10] [43] In a 1971 speech, he predicted that: "By the year 2000 the United Kingdom will be simply a small group of impoverished islands, inhabited by some 70 million hungry people." "If I were a gambler," Professor Ehrlich concluded before boarding an airplane, " I would take even money that England will not exist in the year 2000." [10] [43] When this scenario did not occur, he responded that "When you predict the future, you get things wrong. How wrong is another question. I would have lost if I had had taken the bet. However, if you look closely at England, what can I tell you? They're having all kinds of problems, just like everybody else." [10] Ehrlich wrote in The Population Bomb that, "India couldn't possibly feed two hundred million more people by 1980." [27]
He provided no evidence to support his claim. During the 1960s and 70s when Ehrlich made his most alarming warnings, there was a widespread belief among experts that population growth presented an extremely serious threat to the future of human civilization, although differences existed regarding the severity of the situation, and how to decrease it. [24] [44]
Canadian journalist Dan Gardner, in his 2010 book Future Babble, [45] argues that Ehrlich has been insufficiently forthright in acknowledging errors he made, while being intellectually dishonest or evasive in taking credit for things he claims he got "right". For example, he rarely acknowledges the mistakes he made in predicting material shortages, massive death tolls from starvation (as many as one billion in the publication Age of Affluence) or regarding the disastrous effects on specific countries. Meanwhile, he is happy to claim credit for "predicting" the increase of AIDS or global warming. However, in the case of disease, Ehrlich had predicted the increase of a disease based on overcrowding, or the weakened immune systems of starving people, so it is "a stretch to see this as forecasting the emergence of AIDS in the 1980s." Similarly, global warming was one of the scenarios that Ehrlich described, so claiming credit for it, while disavowing responsibility for failed scenarios is a double standard. Gardner believes that Ehrlich is displaying classical signs of cognitive dissonance, and that his failure to acknowledge obvious errors of his own judgement render his current thinking suspect. [24]
Barry Commoner has criticized Ehrlich's 1970 statement that "When you reach a point where you realize further efforts will be futile, you may as well look after yourself and your friends and enjoy what little time you have left. That point for me is 1972." [46] Gardner has criticized Ehrlich for endorsing the strategies proposed by William and Paul Paddock in their book Famine 1975! . They had proposed a system of "triage" that would end food aid to "hopeless" countries such as India and Egypt. In Population Bomb, Ehrlich suggests that "there is no rational choice except to adopt some form of the Paddocks' strategy as far as food distribution is concerned." Had this strategy been implemented for countries such as India and Egypt, which were reliant on food aid at that time, they would almost certainly have suffered famines. [24] Instead, both Egypt and India have greatly increased their food production and now feed much larger populations without reliance on food aid. [28] [ unreliable source? ]
Another group of critics, generally of the political left, argues that Ehrlich emphasizes overpopulation too much as a problem in itself instead of distribution of resources. [23] Barry Commoner argued that Ehrlich emphasized overpopulation too much as the source of environmental problems, and that his proposed solutions were politically unacceptable because of the coercion that they implied, and because they would cost poor people disproportionately. He argued that technological, and above all social development would result in a natural decrease of both population growth and environmental damage. [47] Ehrlich denies any type of racism, and has argued that if his policy ideas were implemented properly they would not be repressive. [48]
In a 2018 interview with The Guardian, Ehrlich, while still proud of The Population Bomb for starting a worldwide debate on the issues of population, acknowledged weaknesses of the book including not placing enough emphasis on overconsumption and inequality, and countering accusations of racism. He argues "too many rich people in the world is a major threat to the human future, and cultural and genetic diversity are great human resources." He advocated for an "unprecedented redistribution of wealth" in order to mitigate the problem of overconsumption of resources by the world's wealthy, but said "the rich who now run the global system — that hold the annual 'world destroyer' meetings in Davos — are unlikely to let it happen." [40]
Ehrlich and his colleague Rodolfo Dirzo argued in a 2022 perspective paper for the need to reduce fertility rates among "the overconsuming wealthy and middle classes", and wasteful consumption in general, with the ultimate goal being to reduce "the scale of the human enterprise" in order to mitigate the contemporary extinction crisis. [49]
The economist Julian Simon argued in 1980 that overpopulation is not a problem as such and that humanity will adapt to changing conditions. Simon argued that eventually human creativity will improve living standards, and that most resources were replaceable. [50] Simon stated that over hundreds of years, the prices of virtually all commodities had decreased significantly and persistently. [51] Ehrlich termed Simon the proponent of a "space-age cargo cult" of economists convinced that human creativity and ingenuity would create substitutes for scarce resources and reasserted the idea that population growth was outstripping the Earth's supplies of food, fresh water and minerals. [7] This exchange resulted in the Simon–Ehrlich wager, a bet about the trend of prices for resources during a ten-year period that was made with Simon in 1980. [7] Ehrlich was allowed to choose ten commodities that he predicted would become scarce and thus increase in price. Ehrlich chose mostly metals, and lost the bet, as their average price decreased by about 30% in the next 10 years. Simon and Ehrlich could not agree about the terms of a second bet.
Ehrlich has argued that humanity has simply deferred the disaster by the use of more intensive agricultural techniques, such as those introduced during the Green Revolution. Ehrlich claims that increasing populations and affluence are increasingly stressing the global environment, due to such factors as loss of biodiversity, overfishing, global warming, urbanization, chemical pollution and competition for raw materials. [52] He maintains that due to growing global incomes, reducing consumption and human population is critical to protecting the environment and maintaining living standards, and that current rates of growth are still too great for a sustainable future. [53] [54] [55] [56]
Ehrlich was one of the initiators of the group Zero Population Growth (renamed Population Connection) in 1968, along with Richard Bowers and Charles Lee Remington. [57] In 1971, Ehrlich was elected to the Common Cause National Governing Board. He and his wife Anne were part of the board of advisers of the Federation for American Immigration Reform until 2003. He is currently a patron of Population Matters, (formerly known as the Optimum Population Trust). [58]
Consistent with his concern about the impact of pollution and in response to a doctoral dissertation by his student Edward Goth III, Ehrlich wrote in 1977 that, "Fluorides have been shown to concentrate in food chains, and evidence suggesting a potential for significant ecological effects is accumulating." [59]
Ehrlich has spoken at conferences in Israel on the issue of desertification. He has argued "true Zionists should have small families". [60]
Ehrlich has been married to Anne H. Ehrlich (née Howland) since December 1954; they have one daughter, Lisa Marie. [61] He announced that he had had a vasectomy in 1963 after his child's birth. [62]
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. Carrying capacity of the environment implies that the resources extraction is not above the rate of regeneration of the resources and the wastes generated are within the assimilating capacity of the environment. 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.
The Population Bomb is a 1968 book co-authored by former Stanford University professor Paul R. Ehrlich and former Stanford senior researcher in conservation biology Anne H. Ehrlich. From the opening page, it predicted worldwide famines due to overpopulation, as well as other major societal upheavals, and advocated immediate action to limit population growth. Fears of a "population explosion" existed in the mid-20th century baby boom years, but the book and its authors brought the idea to an even wider audience.
The Limits to Growth (LTG) is a 1972 report that discussed the possibility of exponential economic and population growth with finite supply of resources, studied by computer simulation. The study used the World3 computer model to simulate the consequence of interactions between the Earth and human systems. The model was based on the work of Jay Forrester of MIT, as described in his book World Dynamics.
I = (PAT) is the mathematical notation of a formula put forward to describe the impact of human activity on the environment.
Human ecology is an interdisciplinary and transdisciplinary study of the relationship between humans and their natural, social, and built environments. The philosophy and study of human ecology has a diffuse history with advancements in ecology, geography, sociology, psychology, anthropology, zoology, epidemiology, public health, and home economics, among others.
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.
Julian Lincoln Simon was an American economist. He was a professor of economics and business administration at the University of Illinois from 1963 to 1983 before later moving to the University of Maryland, where he taught for the remainder of his academic career.
The Anthropocene was a rejected proposal for a geological epoch following the Holocene, dating from the commencement of significant human impact on Earth up to the present day. This impact affects Earth's oceans, geology, geomorphology, landscape, limnology, hydrology, ecosystems and climate. The effects of human activities on Earth can be seen for example in biodiversity loss and climate change. Various start dates for the Anthropocene have been proposed, ranging from the beginning of the Neolithic Revolution, to as recently as the 1960s. The biologist Eugene F. Stoermer is credited with first coining and using the term anthropocene informally in the 1980s; Paul J. Crutzen re-invented and popularized the term. However, in 2024 the International Commission on Stratigraphy (ICS) and the International Union of Geological Sciences (IUGS) rejected the Anthropocene Epoch proposal for inclusion in the Geologic Time Scale sparking significant disagreement from scientists working in the field.
An ecological or environmental crisis occurs when changes to the environment of a species or population destabilizes its continued survival. Some of the important causes include:
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.
Malthusianism is a theory that population growth is potentially exponential, according to the Malthusian growth model, while the growth of the food supply or other resources is linear, which eventually reduces living standards to the point of triggering a population decline. This event, called a Malthusian catastrophe has been predicted to occur if population growth outpaces agricultural production, thereby causing famine or war. According to this theory, poverty and inequality will increase as the price of assets and scarce commodities goes up due to fierce competition for these dwindling resources. This increased level of poverty eventually causes depopulation by decreasing birth rates. If asset prices keep increasing, social unrest would occur, which would likely cause a major war, revolution, or a famine. Societal collapse is an extreme but possible outcome from this process. The theory posits that such a catastrophe would force the population to "correct" back to a lower, more easily sustainable level. Malthusianism has been linked to a variety of political and social movements, but almost always refers to advocates of population control.
Anne Howland Ehrlich is an American scientist and author who is best known for the predictions she made as a co-author of The Population Bomb with her colleague and husband, Paul R. Ehrlich. She has written or co-written more than thirty books on overpopulation and ecology, including The Stork and the Plow (1995), with Gretchen Daily, and The Dominant Animal: Human Evolution and the Environment (2008), among many other works. She also has written extensively on issues of public concern such as population control, environmental protection, and environmental consequences of nuclear war.
Human impact on the environment refers to changes to biophysical environments and to ecosystems, biodiversity, and natural resources caused directly or indirectly by humans. Modifying the environment to fit the needs of society is causing severe effects including global warming, environmental degradation, mass extinction and biodiversity loss, ecological crisis, and ecological collapse. Some human activities that cause damage to the environment on a global scale include population growth, neoliberal economic policies and rapid economic growth, overconsumption, overexploitation, pollution, and deforestation. Some of the problems, including global warming and biodiversity loss, have been proposed as representing catastrophic risks to the survival of the human species.
The Voluntary Human Extinction Movement (VHEMT) is an environmental movement that calls for all people to abstain from reproduction in order to cause the gradual voluntary extinction of humankind. VHEMT supports human extinction primarily because it would prevent environmental degradation. The group states that a decrease in the human population would prevent a significant amount of human-caused suffering. The extinctions of non-human species and the scarcity of resources caused by humans are frequently cited by the group as evidence of the harm caused by human overpopulation.
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.
Human overpopulation 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.
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.
Environmental issues are disruptions in the usual function of ecosystems. Further, these issues can be caused by humans or they can be natural. These issues are considered serious when the ecosystem cannot recover in the present situation, and catastrophic if the ecosystem is projected to certainly collapse.
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.
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.
Ehrlich's prophecy, of course, proved wrong, for reasons that Bricker and Ibbitson elegantly chart in Empty Planet.
Ehrlich's argument that expanding human populations cannot be sustained on an Earth with finite carrying capacity is irrefutable and, indeed, almost tautological. The only uncertainty concerns the timing and severity of the rebalancing that must inevitably occur.
Some things I predicted have not come to pass.
Ehrlich was right, however, to point out that humanity's impact on the planet is a combination of three elements: our numbers, our consumption patterns and how we produce what we consume. So, because massive poverty and unmet demand for basic goods is a widespread problem in much of the poor world today, we still face a "consumption bomb" — our growing demands for both consumer goods and life necessities are responsible for runaway climate change and the depletion of soils, water and other essential planetary life-support systems.
In 1967 Paul Ehrlich predicted that the world was headed for massive starvation and it was already too late to do anything about it. In order to limit the extent of this, he believed – reasonably enough given his point of view – that aid should be given only to those countries that would have a chance to make it through. According to Ehrlich, India was not among them. We must "announce that we will no longer send emergency aid to countries such as India where sober analysis shows a hopeless imbalance between food production and population ... Our inadequate aid ought to be reserved for those which can survive."
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. Analysts' estimate of that population size vary between 2 and 4 billion people, a figure obviously well below the present 7.9.
Again, not totally accurate, but I never claimed to predict the future with full accuracy
Population control (as distinct from voluntary, self-initiated control of fertility), no matter how disguised, involves some measure of political repression, and would burden the poor nations with the social cost of a situation — overpopulation — which is the current outcome of their previous exploitation, as colonies, by the wealthy nations.
It is clear that only a giant change in human culture can significantly limit the extinction crisis. Humanity must face the need to reduce birth rates further, especially among the overconsuming wealthy and middle classes. In addition, a reduction of wasteful consumption will be necessary, accompanied by a transition away from environmentally malign technological choices such as private automobiles, plastic everything, and treating billionaires to space tourism. Otherwise growthmania will win; the human enterprise will not undergo the needed shrinkage, but will continue to expand, destroying most of biodiversity and further wrecking the life-support systems of humanity until global civilization collapses
...nearly all resources in the past were much more expensive than they are today
Consumption is equally important. I'd think the biggest problem is figuring out what to do on consumption. We don't have any consumption condoms.