Conservation biologists agree that humanity is on the verge of causing a mass extinction and that its primary driver is our immense and rapidly expanding global economy. We are replacing Earth’s ten million wild species with more of ourselves, our domesticated species, our economic support systems, and our trash. In the process, we are creating a duller, tamer, and more dangerous world. The moral case for reducing excessive human impacts on the biosphere is strong on both anthropocentric and biocentric ethical grounds. The sine qua non for doing so is reducing human numbers and the size of our economies, while increasing the global acreage set aside in protected areas. We should take these steps as part of comprehensive efforts to create just and sustainable societies in which both humans and other species can flourish.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Price excludes VAT (USA)
Tax calculation will be finalised during checkout.
Angus, I., & Butler, S. (2011). Too many people? Population, immigration, and the environmental crisis. Haymarket.
Asafu-Adjaye, J., et al. (2015). An ecomodernist manifesto. Breakthrough Institute.
Beckerman, W., & Pasek, J. (2001). Justice, posterity and the environment. Oxford.
Bell, D. (2015). Justice on one planet. In S. Gardiner & A. Thompson (Eds.), The Oxford Handbook of Environmental Ethics. Oxford.
Bourban, M. (2019). Croissance démographique et changement climatique: repenser nos politiques dans le cadre des limites planétaires. La Pensée Ecologique, 3, 19–37.
Bradshaw, C., et al. (2021). Underestimating the challenges of avoiding a ghastly future. Frontiers of Conservation Science, 1, 615419.
Burket, D. (2021). A legacy of harm? Climate change and the carbon cost of procreation. Journal of Applied Philosophy, 38. https://doi.org/10.1111/japp.12515
Büscher, B., et al. (2016). Half-Earth or whole Earth? Radical ideas for conservation, and their implications. Oryx, 51, 407–410.
Butchart, S., et al. (2010). Global biodiversity: indicators of recent declines. Science, 328, 1164–1168.
Cafaro, P. (2001). The naturalist's virtues. Philosophy in the Contemporary World, 8, 85–99.
Cafaro, P. (2010). Economic growth or the flourishing of life: The ethical choice global climate change puts to humanity in the 21st century. Essays in Philosophy, 11, article 6.
Cafaro, P. (2015). Three ways to think about the sixth mass extinction. Biological Conservation, 192, 387–393.
Cafaro, P. (2021). Just population policies for an overpopulated world. Ecological Citizen, 5, epub-046.
Cafaro, P., & Götmark, F. (2019). The potential environmental impacts of EU immigration policy: Future population numbers, greenhouse gas emissions and biodiversity preservation. Journal of Population and Sustainability, 4, 71–101.
Cafaro, P., & Primack, R. (2014). Species extinction is a great moral wrong. Biological Conservation, 170, 1–2.
Callicott, B., & Grove-Fanning, W. (2009). Should endangered species have standing? Toward legal rights for listed species. Social Philosophy and Policy, 26, 317–352.
Caney, S. (2014). Climate change, intergenerational equity and the social discount rate. Politics, Philosophy & Economics, 13, 320–342.
Caney, S. (2018). On cosmopolitanism: Equality, ecology and resistance. Oxford.
Carson, R. (1962). Silent spring. Fawcett.
Carson, R. (1998). Lost woods: The discovered writing of Rachel Carson. Beacon.
Ceballos, C., et al. (2015). Accelerated modern human-induced species losses: entering the sixth mass extinction. Science Advances, 1, e1400253.
Conly, S. (2016). One child: Do we have a right to more? Oxford.
Coole, D. (2018). Should we control world population? Polity.
Cottingham, J., et al. (2012). Use of human rights to meet the unmet need for family planning. Lancet, 380, 172–180.
Cripps, E. (2015). Climate change, population, and justice: Hard choices to avoid tragic choices. Global Justice: Theory Practice Rhetoric, 8, 1–22.
Crist, E. (2019). Abundant Earth: Toward an ecological civilization. University of Chicago.
Crist, E., et al. (2017). The interaction of human population, food production, and biodiversity protection. Science, 356, 260–264.
Crist, E., et al. (2021). Protecting half the planet and transforming human systems are complementary goals. Frontiers in Conservation Science, 2, 781292.
Daly, H., & Farley, J. (2010). Ecological economics, second edition: Principles and applications. Island.
Dasgupta, P. (2019). Time and the generations: Population ethics for a diminishing planet. Columbia.
Diaz, S., et al. (2019). Pervasive human-driven decline of life on Earth points to the need for transformative change. Science, 366, 1327.
Dilworth, C. (2010). Too smart for our own good: The ecological predicament of mankind. Cambridge.
Dinerstein, E., et al. (2017). An ecoregion-based approach to protecting half the terrestrial realm. BioScience, 67, 534–545.
D’Odorico, P., et al. (2018). The global food-energy-water nexus. Reviews of Geophysics, 56, 456–531.
Dodson, J., et al. (2020). Population growth and climate change: Addressing the overlooked threat multiplier. Science of the Total Environment, 748, 141346.
Donaldson, S., & Kymlicka, W. (2011). Zoopolis: A political theory of animal rights. Oxford.
European Parliament. (2020). Resolution of 16 January 2020 on the 15th meeting of the Conference of Parties (COP15) to the Convention on Biological Diversity (2019/2824(RSP)).
Foreman, D., & Carroll, L. (2014). Man swarm: How overpopulation is killing the wild world. LiveTrue.
Friedman, B. (2006). The moral consequences of economic growth. Vintage.
Gheaus, A. (2016). The right to parent and duties concerning future generations. Journal of Political Philosophy, 24, 487–508.
Griscom, B., et al. (2017). Natural climate solutions. PNAS, 114, 11645–11650.
Hall, C., et al. (2017). The impact of population growth and climate change on food security in Africa: looking ahead to 2050. International Journal of Agricultural Sustainability, 15, 124–135.
Hardee, K., et al. (2013). Voluntary family planning programs that respect, protect, and fulfill human rights: Conceptual framework users’ guide. Futures Group.
Hartmann, B. (2016). Reproductive rights and wrongs: The global politics of population control. Haymarket.
Hedberg, T. (2020). The environmental impact of overpopulation. Routledge.
Hendrixson, A., et al. (2019). Confronting populationism: Feminist challenges to population control in an era of climate change. Gender, Place & Culture, 27, 307–315.
Hendrixson, A., & Hartmann, B. (2019). Threats and burdens: Challenging scarcity-driven narratives of “overpopulation”. Geoforum, 101, 250–259.
Higgs, K. (2017). Limits to growth: human economy and planetary boundaries. Journal of Population and Sustainability, 2, 15–36.
Holland, B. (2022). Capabilities, future generations, and climate justice. In S. Gardiner (Ed.), The Oxford handbook of intergenerational ethics (online). Oxford.
IPBES. (2019). Summary for policymakers. Global assessment report on biodiversity and ecosystem services. Intergovernmental Panel on Biodiversity and Ecosystem Services Secretariat.
IPCC. (2014). Summary for policymakers. Climate change 2014: Mitigation of climate change. Cambridge. Intergovernmental Panel on Climate Change.
Johns, D. (2019). Conservation politics: The last anti-colonial battle. Cambridge.
Kahn, P., & Hasbach, P. (Eds.). (2013). The rediscovery of the wild. MIT.
Kallhoff, A. (2021). The intergenerational value of natural heritage. In S. Gardiner (Ed.), The Oxford handbook of intergenerational ethics (online). Oxford.
Kareiva, P., et al. (2011). Conservation in the anthropocene: Beyond solitude and fragility. Breakthrough Journal, 29–37 (Fall).
Kareiva, P., & Marvier, M. (2012). What is conservation science? BioScience, 62, 962–969.
Leopold, A. (1966). A sand county almanac with essays on conservation from Round River. Oxford.
Lieberman, B. (2021). Details behind Biden’s ‘30 by 30′ U.S. lands and oceans climate goal. Yale Climate Connections.
Lianos, P., & Pseiridis, A. (2016). Sustainable welfare and optimum population size. Environmental Development and Sustainability, 18, 1679–1699.
Locke, H. (2015). Nature needs (at least) half: A necessary new agenda for protected areas. In G. Wuerthner et al. (Eds.), Protecting the wild: Parks and wilderness, the foundation for conservation (pp. 3–15). Island.
Locke, H., et al. (2019). Three global conditions for biodiversity conservation and sustainable use: An implementation framework. National Science Review, 6, 1080–1082.
Louv, R. (2019). Outdoors for all: A nascent global movement proclaims that access to nature is a human right. Sierra, May/June, 2019.
Mangrum, B. (2021). Rachel Carson, environmental rights, and the publicity of aesthetic judgments. ELH, 88, 765–793.
Marques, A., et al. (2019). Increasing impacts of land use on biodiversity and carbon sequestration driven by population and economic growth. Nature: Ecology & Evolution, 3, 628–637.
Matanle, P. (2017). Towards an Asia-Pacific depopulation dividend in the 21st century: regional growth and shrinkage in Japan and New Zealand. The Asia-Pacific Journal, 15, article 5018.
McNeill, J., & Engelke, P. (2014). The great acceleration: An environmental history of the anthropocene since 1945. Harvard.
Meadows, D., et al. (2004). Limits to growth: The 30-year update. Chelsea Green.
Meijers, T. (2016). Climate change and the right to one child. In G. Bos & M. Düwell (Eds.), Human rights and sustainability (pp. 181–194). Routledge.
Meyer, L. (2009). Sufficientarianism both international and intergenerational? In E. Mack et al. (Eds.), Absolute poverty and global justice (pp. 133–144). Ashgate.
Navarro, L., & Pereira, H. (2015). Rewilding abandoned landscapes in Europe. In H. Pereira & L. Navarro (Eds.), Rewilding European landscapes (pp. 3–15). Springer International.
Nolt, J. (2021). Long-term non-anthropocentric ethics. In S. Gardiner (Ed.), The Oxford handbook of intergenerational ethics (online). Oxford.
Noss, R. (2020). The spectrum of wildness and rewilding: Justice for all. In H. Kopnina & H. Washington (Eds.), Conservation: Integrating social and ecological justice. Springer Nature.
Noss, R., et al. (2013). Humanity’s domination of nature is part of the problem: a response to Kareiva and Marvier. BioScience, 63, 241–242.
O'Leary, B., et al. (2016). Effective coverage targets for ocean protection. Conservation Letters, 9, 398–404.
O'Sullivan, J. (2018). Synergy between population policy, climate adaptation and mitigation. In M. Hossain et al. (Eds.), Pathways to a sustainable economy (pp. 103–127). Springer.
Palmer, C. (2009). Harm to species? Species, ethics and climate change: The case of the polar bear. Notre Dame Journal of Law, Ethics and Public Policy, 23, 587–603.
Pimm, S., et al. (2014). The biodiversity of species and their rates of extinction, distribution, and protection. Science, 344, 1246752-1–1246752-10.
Queiroz, C., et al. (2014). Farmland abandonment: Threat or opportunity for biodiversity conservation? A global review. Frontiers in Ecology and the Environment, 12, 288–296.
Raven, P., et al. (2011). Introduction to special issue on biodiversity. American Journal of Botany, 98, 333–335.
Rewilding Charter Working Group. (2020). Global charter for rewilding Earth. The Ecological Citizen, 4 (Suppl A), 6–21.
Rieder, T. (2016). Toward a small family ethic: How overpopulation and climate change are affecting the morality of procreation. Springer.
Ripple, W., et al. (2020). World scientists’ warning of a climate emergency. BioScience, 70, 8–12.
Robeyns, I. (2021). Is procreation special? The Journal of Value Inquiry. https://doi.org/10.1007/s10790-021-09797-y.
Rolston, H., III (1989). Values in Nature. In Rolston, H., III, Philosophy Gone Wild: Environmental Ethics (pp. 74–90). Prometheus.
Rolston III, H. (1994). Conserving Natural Value. Columbia.
Rolston III, H. (2008). Mountain Majesties Above Fruited Plains. Environmental Ethics, 30, 3–20.
Rolston III, H. (2020). A New Environmental Ethics. Routledge.
Rosenberg, K., et al. (2019). Decline of the North American avifauna. Science, 366, 120–124.
Sandler, R. (2012). The ethics of species: An introduction. Cambridge.
Sandler, R. (2021). On the massness of mass extinction. Philosophia (online first articles).
Secretariat of the Convention on Biological Diversity. (2010). Global Biodiversity Outlook 3. Secretariat of the Convention on Biological Diversity.
Shoreman-Ouimet, E., & Kopnina, H. (2015). Reconciling ecological and social justice to promote biodiversity conservation. Biological Conservation, 184, 320–326.
Shragg, K. (2015). Move upstream: A call to solve overpopulation. Freethought House.
Shue, H. (1993). Subsistence emissions and luxury emissions. Law Policy, 15, 39–59.
Smirnov, O., et al. (2016). The relative importance of climate change and population growth for exposure to future extreme droughts. Climate Change, 138, 41–53.
Smith, I. (2022). Incalculable instrumental value in the Endangered Species Act. Philosophia (online first articles).
Staples, W., & Cafaro, P. (2012). For a species right to exist. In P. Cafaro & E. Crist (Eds.), Life on the brink: Environmentalists confront overpopulation (pp. 283–300). University of Georgia.
Steffen, W., et al. (2015). Planetary boundaries: Guiding human development on a changing planet. Science, 347, 1259855.
Steffen, W., et al. (2018). Trajectories of the earth system in the anthropocene. PNAS, 115, 8252–8259.
Stuart, D., et al. (2020). The degrowth alternative: A path to address our environmental crisis? Routledge.
Tamburino, L., & Bravo, G. (2021). Reconciling a positive ecological balance with human development: A quantitative assessment. Ecological Indicators, 129, 107973.
Thoreau, H. (1962). The journal of Henry D. Thoreau. Dover.
Tucker, C. (2019). A planet of 3 billion. Atlas Observatory.
United Nations. (2019). World population prospects. UN Department of Economic and Social Affairs, Population Division.
Weber, H., & Sciubba, J. (2018). The effect of population growth on the environment: evidence from European regions. European Journal of Population, 35, 379–402.
Wessels, T. (2013). The myth of progress: Toward a sustainable future. University Press of New England.
Wienhues, E. (2018). Situating the half-earth proposal in distributive justice: Conditions for just Conservation. Biological Conservation, 228, 44–51.
Wilson, E. (2016). Half Earth: Our planet's fight for life. Norton.
World Wildlife Fund. (2020). Living planet report 2020 - Bending the curve of biodiversity loss. WWF.
Availability of data and material
This paper was funded in part through sabbatical support from the Philosophy Department and the College of Liberal Arts at Colorado State University, Fort Collins, CO. It was written over the course of the Bodaken Seminar on Extinction Ethics, funded through the generosity of Bruce Bodaken of Mill Valley, California.
Conflicts of interest/Competing interests
I declare no conflict of interest or competing interests involved in my authorship of this article.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Cafaro, P. Reducing Human Numbers and the Size of our Economies is Necessary to Avoid a Mass Extinction and Share Earth Justly with Other Species. Philosophia 50, 2263–2282 (2022). https://doi.org/10.1007/s11406-022-00497-w