Beyond Population Stabilization: The Case for Dramatically Reducing Global Human Numbers

1997 ◽  
Vol 16 (2) ◽  
pp. 183-192 ◽  
Author(s):  
J. Kenneth Smail
Keyword(s):  
Population Size ◽  
Carrying Capacity ◽  
Standard Of Living ◽  
World Population ◽  
Past Time ◽  
Demographic Projections ◽  
Global Population ◽  
Population Stabilization

There is a growing tension between two apparently irreconcilable trends: (1) demographic projections that world population size will reach 10 to 11 billion by the middle of the next century; and (2) scientific estimates that the Earth's long-term sustainable carrying capacity (at an “adequate to comfortable” standard of living) may not be much greater than 2 to 3 billion. It is past time to develop internationally coordinated sociopolitical initiatives that go beyond slowing the growth or stabilizing global human numbers. After “inescapable realities” that humans must soon confront, and notwithstanding the considerable difficulties involved in establishing “global population optimums,” I conclude with several suggestions how best to bring about a very significant reduction in global population over the next two to three centuries. These proposals are cautiously optimistic.

scholarly journals Can we reestablish a self-sustaining population? A case study on reintroduced Crested Ibis with population viability analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yashuai Zhang ◽  
Fang Wang ◽  
Zhenxia Cui ◽  
Min Li ◽  
Xia Li ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Carrying Capacity ◽  
Wild Population ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Viability Analysis ◽  
Crested Ibis ◽  
Reintroduced Population

Abstract Background One of the most challenging tasks in wildlife conservation and management is clarifying which and how external and intrinsic factors influence wildlife demography and long-term viability. The wild population of the Crested Ibis (Nipponia nippon) has recovered to approximately 4400, and several reintroduction programs have been carried out in China, Japan and Korea. Population viability analysis on this endangered species has been limited to the wild population, showing that the long-term population growth is restricted by the carrying capacity and inbreeding. However, gaps in knowledge of the viability of the reintroduced population and its drivers in the release environment impede the identification of the most effective population-level priorities for aiding in species recovery. Methods The field monitoring data were collected from a reintroduced Crested Ibis population in Ningshan, China from 2007 to 2018. An individual-based VORTEX model (Version 10.3.5.0) was used to predict the future viability of the reintroduced population by incorporating adaptive patterns of ibis movement in relation to catastrophe frequency, mortality and sex ratio. Results The reintroduced population in Ningshan County is unlikely to go extinct in the next 50 years. The population size was estimated to be 367, and the population genetic diversity was estimated to be 0.97. Sensitivity analysis showed that population size and extinction probability were dependent on the carrying capacity and sex ratio. The carrying capacity is the main factor accounting for the population size and genetic diversity, while the sex ratio is the primary factor responsible for the population growth trend. Conclusions A viable population of the Crested Ibis can be established according to population viability analysis. Based on our results, conservation management should prioritize a balanced sex ratio, high-quality habitat and low mortality.

scholarly journals Historical population size of the threatened New Zealand sea lion Phocarctos hookeri

2015 ◽  
Vol 97 (2) ◽  
pp. 436-443 ◽  
Author(s):  
Catherine J. Collins ◽  
B. Louise Chilvers ◽  
Matthew Taylor ◽  
Bruce C. Robertson
Keyword(s):  
New Zealand ◽  
Population Size ◽  
Effective Population Size ◽  
Carrying Capacity ◽  
Effective Population ◽  
Sea Lion ◽  
Sea Lions ◽  
Target Values ◽  
Phocarctos Hookeri

Abstract Marine mammal species were exploited worldwide during periods of commercial sealing in the 18th and 19th centuries. For many of these species, an estimate of the pre-exploitation abundance of the species is lacking, as historical catch records are generally scarce and inaccurate. Genetic estimates of long-term effective population size provide a means to estimate the pre-exploitation abundance. Here, we apply genetic methods to estimate the long-term effective population size of the subantarctic lineage of the New Zealand sea lion (NZ sea lion), Phocarctos hookeri . This species is predominantly restricted to the subantarctic islands, south of mainland New Zealand, following commercial sealing in the 19th century. Today, the population consists of ~9,880 animals and population growth is slow. Auckland Island breeding colonies of NZ sea lion are currently impacted by commercial trawl fisheries via regular sea lion deaths as bycatch. In order to estimate sustainable levels of bycatch, an estimate of the population’s carrying capacity ( K ) is required. We apply the genetically estimated long-term effective population size of NZ sea lions as a proxy for the estimated historical carrying capacity of the subantarctic population. The historical abundance of subantarctic NZ sea lions was significantly higher than the target values of K employed by the contemporary management. The current management strategy may allow unsustainable bycatch levels, thereby limiting the recovery of the NZ sea lion population toward historical carrying capacity.

scholarly journals Dimensions of global population projections: what do we know about future population trends and structures?

2010 ◽  
Vol 365 (1554) ◽  
pp. 2779-2791 ◽  
Author(s):  
Wolfgang Lutz ◽  
Samir KC
Keyword(s):  
Population Projections ◽  
World Population ◽  
Mortality Trends ◽  
Total Size ◽  
Future Fertility ◽  
Western Asia ◽  
The World ◽  
Global Population ◽  
Population Stabilization ◽  
Future Population

The total size of the world population is likely to increase from its current 7 billion to 8–10 billion by 2050. This uncertainty is because of unknown future fertility and mortality trends in different parts of the world. But the young age structure of the population and the fact that in much of Africa and Western Asia, fertility is still very high makes an increase by at least one more billion almost certain. Virtually, all the increase will happen in the developing world. For the second half of the century, population stabilization and the onset of a decline are likely. In addition to the future size of the population, its distribution by age, sex, level of educational attainment and place of residence are of specific importance for studying future food security. The paper provides a detailed discussion of different relevant dimensions in population projections and an evaluation of the methods and assumptions used in current global population projections and in particular those produced by the United Nations and by IIASA.

Predictions of the impacts of changes in population size and environmental variablitity on Leadbeater's possum, Gymnobelideus leadbeateri McCoy (Marsupialia: Petauridae) using population viability analysis: an application of the computer program VORTEX.

1993 ◽  
Vol 20 (1) ◽  
pp. 67 ◽  
Author(s):  
DB Lindenmayer ◽  
RC Lacy ◽  
VC Thomas ◽  
TW Clark
Keyword(s):  
Computer Program ◽  
Population Size ◽  
Carrying Capacity ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Suitable Habitat ◽  
Viability Analysis ◽  
Nest Sites ◽  
Leadbeater's Possum

Population Viability Analysis (PVA) uses computer modelling to simulate interacting deterministic and stochastic factors (e.g. demographic, genetic, spatial, environmental and catastrophic processes) that act on small populations and assess their long-term vulnerability to extinction. The computer program VORTEX was used in a PVA of Leadbeater's possum, Gymnobelideus leadbeateri McCoy, an endangered arboreal marsupial that is restricted to the montane ash forests of the central highlands of Victoria. PVA was used to examine the impacts of changes in the size of subpopulations and the effects of environmental variation. Our analyses demonstrated that an annual linear decline in the carrying capacity in all or parts of the habitat will lead to the extinction of G. leadbeateri in those areas. Mean time to extinction was related to the rate of annual decrease. This conclusion is of practical and management importance as there is presently a decline in suitable habitat because of an annual loss of more than 3.5% of trees with hollows, which provide nest sites for G. leadbeateri. Because nest sites are a factor that limits populations of G. leadbeateri, the species could be lost from large areas within the next 50 years. PVA was also used to determine the viability of populations in areas, such as oldgrowth forest, where there is not likely to be a steady decline in habitat carrying capacity resulting from the loss of trees with hollows. This allowed an analysis of the cumulative impacts of small population size, environmental variation and genetic factors, which showed that, for a 100-year projection, simulated populations of 200 animals or more remained demographically stable and experienced a less than 10% decline in predicted genetic variability. However, the relatively simplified nature of population modelling and the suite of assumptions that underpin VORTEX mean that the probability of extinction of populations of this size may be greater than determined in this study. As a result, it is possible that only populations of more than 200 animals may persist in the long term where suitable habitat can be conserved or established and subsequently maintained without a reduction in carrying capacity.

scholarly journals We know how many people the earth can support

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Christopher Tucker
Keyword(s):  
Carrying Capacity ◽  
Quarter Century ◽  
New Science ◽  
Ecological Carrying Capacity ◽  
The Earth ◽  
Global Middle Class ◽  
Essential Question ◽  
The Face ◽  
Global Population

A quarter century after Joel Cohen asked the essential question “How Many People can the Earth Support?”, this article offers an answer, based on new science and geographical analysis, and asserts that we have long ago exceeded our planet’s long term ecological carrying capacity that optimistically can only support 3 billion modern industrialized humans. While agreeing that strategies based on reducing consumption are sorely needed to live within our planet’s carrying capacity, the impending explosion of the global middle class promises to render consumption-only strategies inadequate, in the face of runaway population growth and the accumulation of massive ecological debt. Noting recent studies that project global population to begin to decrease in 2064 after peaking at 9.7B, it is asked why we don’t act now to accelerate this already inevitable trend with enhanced investment in women’s empowerment, education, and access to family planning technologies. This paper calls for a goal of achieving 1.5 total fertility rate (TFR) by 2030 to bend the global population curve, begin relieving the ecological burden humanity has foisted on our planet, and to decrease human population as we approach 2100 to something closer to the long term ecological carrying capacity of our planet.

scholarly journals First formal estimate of the world population of the Critically Endangered spoon-billed sandpiper Calidris pygmaea

Oryx ◽  
2016 ◽  
Vol 52 (1) ◽  
pp. 137-146 ◽  
Author(s):  
Nigel A. Clark ◽  
Guy Q. A. Anderson ◽  
Jing Li ◽  
Evgeny E. Syroechkovskiy ◽  
Pavel S. Tomkovich ◽  
...  
Keyword(s):  
Population Size ◽  
Breeding Population ◽  
Critically Endangered ◽  
World Population ◽  
South East Asia ◽  
Russian Arctic ◽  
Age Classes ◽  
Long Distance ◽  
The World ◽  
Global Population

AbstractThe spoon-billed sandpiper Calidris pygmaea is a Critically Endangered shorebird that breeds in the Russian arctic and winters in coastal and estuarine habitats in South-east Asia. We report the first formal estimate of its global population size, combining a mark–resighting estimate of the number of leg-flagged individuals alive in autumn 2014 with an estimate of the proportion of birds with flags from scan surveys conducted during the same period at a migration stop-over site on the Jiangsu coast of China. We estimate that the world breeding population of spoon-billed sandpipers in 2014 was 210–228 pairs and the post-breeding population of all age classes combined was 661–718 individuals. This and related methods have considerable potential for surveillance of the population size of other globally threatened species, especially widely dispersed long-distance migrants.

scholarly journals Global association of obesity and COVID-19 death rates

2021 ◽  
Author(s):  
Mary L. Adams
Keyword(s):  
Least Squares ◽  
Population Size ◽  
World Population ◽  
Death Rates ◽  
Death Toll ◽  
Key Factor ◽  
The Difference ◽  
Best Fit ◽  
Global Population ◽  
Death Data

AbstractImportanceCOVID-19 was responsible for an enormous global death toll with large variation among countries.ObjectiveTo examine the possible impact of obesity on COVID-19 death rates.DesignMeasure associations between obesity rates in 2016 and COVID-19 deaths/million population through 2/25/2021, across countries.SettingGlobalParticipants167 countries for which obesity and death data were available, grouped by population size, with multiples of 10 countries in each of 8 groups plus a group including all 57 countries with obesity rates <15%.Outcome and measuresUsing Excel, COVID-19 deaths/million were regressed on the obesity rate for each country, based on obesity being a key factor in COVID hospitalizations and deaths. Using the least squares formula for the best fit for each model, R2, components of the formula, and the percentage of world population represented, were recorded for each group.ResultsObesity rates ranged from 2.1% to 37.9% and death rates ranged from 0.4/million to 1,892/million for groups representing up to 91% of global population. Results for the 8 population groups had R2 from 0.30 to 0.90 with slopes of the fitted line ranging from 27.9-51.0. Countries with obesity rates <15% had consistently low death rates (≤233/million), R2 of 0.003 and slope of the line=1.01.ConclusionsFor most countries about one-third of the difference in COVID death rates was due to obesity while in countries with obesity <15%, consistently low death rates were not associated with obesity. Reduced obesity rates could potentially have lowered the COVID death toll.

scholarly journals First census of the white-shouldered ibis Pseudibis davisoni reveals roost-site mismatch with Cambodia's protected areas

Oryx ◽  
2012 ◽  
Vol 46 (2) ◽  
pp. 236-239 ◽  
Author(s):  
Hugh L. Wright ◽  
Nigel J. Collar ◽  
Iain R. Lake ◽  
Net Norin ◽  
Rours Vann ◽  
...  
Keyword(s):  
Protected Areas ◽  
Population Size ◽  
Critically Endangered ◽  
Population Estimate ◽  
Term Survival ◽  
Long Term Survival ◽  
Global Population

AbstractThe population size of the Critically Endangered white-shouldered ibis Pseudibis davisoni has always been poorly known. The first-ever census across Cambodia in 2009–2010 using simultaneous counts at multiple roost sites found substantially more birds than previously estimated, with a minimum of 523 individuals. The census allowed us to make a revised global population estimate of 731–856 individuals, increasing hope for the species' long-term survival. However, the largest subpopulations are imminently threatened by development and c. 75% of the birds counted in Cambodia were outside protected areas.

scholarly journals Ecological and Evolutionary Oscillations in Host-Parasite Population Dynamics, and The Red Queen

2014 ◽  
Author(s):  
Jomar Fajardo Rabajante
Keyword(s):  
Population Size ◽  
Carrying Capacity ◽  
Quantitative Traits ◽  
Oscillatory Behavior ◽  
Red Queen ◽  
Trade Off ◽  
Oscillatory Dynamics ◽  
Host Parasite ◽  
The Red Queen

In a host-parasite system, the constitutive interaction among the species, regulated by the growth rates and functional response, may induce populations to approach equilibrium or sometimes to exhibit simple cycles or peculiar oscillations, such as chaos. A large carrying capacity coupled with appropriate parasitism effectiveness frequently drives long-term apparent oscillatory dynamics in population size. We name these oscillations due to the structure of the constitutive interaction among species as ecological. On the other hand, there are also exceptional cases when the evolving quantitative traits of the hosts and parasites induce oscillating population size, which we call as evolutionary. This oscillatory behavior is dependent on the speed of evolutionary adaptation and degree of evolutionary trade-off. A moderate level of negative trade-off is essential for the existence of oscillations. Evolutionary oscillations due to the host-parasite coevolution (known as the Red Queen) can be observed beyond the ecological oscillations, especially when there are more than two competing species involved.

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