Models and estimates of Earth’s human carrying capacity vary widely and assume, rather than solve for, binding environmental constraints (the process or resource in shortest supply relative to human biological needs). The binding constraint, and therefore the true upper bound on the number of humans that Earth could sustain indefinitely, remains unknown. We seek to resolve this uncertainty by considering a full range of technological possibilities and incorporating a potential stoichiometric constraint not previously explored. We find that limits to photosynthesis constrain population before micronutrients become limiting unless technological capabilities for utilizing nutrient resources lag far behind other technologies. With ideal technology, human carrying capacity runs into the tens of trillions, while with currently demonstrated technology Earth could support more than 200 billion humans. These numbers reflect neither a desirable nor a natural equilibrium population level, but represent a rough estimate of the maximum number of humans Earth could sustain.
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Data Availability Statement
The datasets generated and analyzed during the current study were derived from publicly available data sources, as cited. The data generated for use as immediate input to our model are available in the figshare repository at doi.org/10.6084/m9.figshare.9983369. Model code can be found at https://github.com/binders1/maxpop.
Arrow, K., Bolin, B., Costanza, R., Dasgupta, P., Folke, C., Holling, C. S., et al. (1996). Economic growth, carrying capacity, and the environment. Ecological applications, 6(1), 13–15.
Badescu, V., & Cathcart, R. B. (2006). Environmental thermodynamic limitations on global human population. International journal of global energy issues, 25(1-2), 129–140.
Blankenship, R. E., Tiede, D. M., Barber, J., Brudvig, G. W., Fleming, G., Ghirardi, M., et al. (2011). Comparing photosynthetic and photovoltaic efficiencies and recognizing the potential for improvement. Science, 332(6031), 805–809.
Brown, H. (1954). The challenge of man's future: An inquiry concerning the condition of man during the years that lie ahead. New York: Viking Press.
Cao, M., Ma, S., & Han, C. (1995). Potential productivity and human carrying capacity of an agro-ecosystem: An analysis of food production potential of China. Agricultural systems, 47(4), 387–414.
Clark, C. (1958). World population. Nature, 181(4618), 1235–1236.
Clarke FW, Washington HS. The composition of the earth's crust. US government printing office. 1924
Cohen, J. E. (1995). How many people can the earth support? The sciences, 35(6), 18–23.
Costanza, R., Wainger, L., Folke, C., & Mäler, K. G. (1993 Sep 1). Modeling complex ecological economic systems: Toward an evolutionary, dynamic understanding of people and nature. BioScience, 43(8), 545–555.
Daily, G. C., & Ehrlich, P. R. (1992 Nov 1). Population, sustainability, and Earth's carrying capacity. Bioscience, 42(10), 761.
Daily, G. C., Ehrlich, A. H., & Ehrlich, P. R. (1994 Jul). Optimum human population size. Population and environment, 1, 469–475.
Dasgupta, P. S. (1969 Jul 1). On the concept of optimum population. The review of economic studies, 36(3), 295–318.
Davidsson, S., & Höök, M. (2017 Sep 1). Material requirements and availability for multi-terawatt deployment of photovoltaics. Energy policy, 108, 574–582.
De Vos, A. (1980 May 14). Detailed balance limit of the efficiency of tandem solar cells. Journal of physics D: Applied physics, 13(5), 839.
De Wit CT. Photosynthesis: its relation to overpopulation. In IMC Symposium. Harvesting the Sun: Photosynthesis in plant life. 1967 (pp. 315-320).
Díaz, S., & Settele, J. (2019). Brondizio ES, et al. IPBES Secretariat: Global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.
Dimov, D., Amit, I., Gorrie, O., Barnes, M. D., Townsend, N. J., Neves, A. I., et al. (2018 Jun). Ultrahigh performance nanoengineered graphene–concrete composites for multifunctional applications. Advanced functional materials, 28(23), 1705183.
Franck, S., von Bloh, W., Müller, C., Bondeau, A., & Sakschewski, B. (2011). Harvesting the sun: New estimations of the maximum population of planet earth. Ecological modelling, 222(12), 2019–2026.
Fremlin, J. H. (1964). How many people can the world support. New scientist, 415(29), 285–287.
Fukuyama, F. (2002). Our posthuman future: Consequences of the biotechnology revolution (1st ed., p. 256). New York: Farrar, Straus and Giroux.
Gleick, P. H. (1993). Water in crisis: A guide to the world's fresh water resources. New York: Oxford University Press.
Graedel, T. E., Harper, E. M., Nassar, N. T., & Reck, B. K. (2015 May 19). On the materials basis of modern society. Proceedings of the National Academy of Sciences, 112(20), 6295–6300.
Hardin, G. (1986). Cultural carrying capacity: A biological approach to human problems. BioScience, 36(9), 599–606.
Hargreaves, G. H., & Samani, Z. A. (1985). Reference crop evapotranspiration from temperature. Applied engineering in agriculture, 1(2), 96–99.
Hay, R. (1995). Harvest index: A review of its use in plant breeding and crop physiology. The annals of applied biology, 126(1), 197–216.
Haynes, W. (2010). CRC handbook of chemistry and physics: CRC press.
Huffman G. J., Bolvin D. T., and Adler R. F. (2016). GPCP Version 1.2 One-Degree Daily Precipitation Data Set. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory.
Ingenbleek, Y. (2006). The nutritional relationship linking sulfur to nitrogen in living organisms. The journal of nutrition, 136(6), 1641S–1651S.
IPCC. Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland; 2014. 151 pp.
Isbell, F., & Loreau, M. (2014 Mar). Sustainability of human ecological niche construction. Ecology and society, 1, 19(1).
Kaack, L. H., & Katul, G. G. (2013). Fifty years to prove Malthus right. Proceedings of the National Academy of Sciences, 110(11), 4161–4162.
Kempes, C. P., van Bodegom, P. M., Wolpert, D., Libby, E., Amend, J., & Hoehler, T. (2017 Jan 31). Drivers of bacterial maintenance and minimal energy requirements. Frontiers in microbiology, 8, 31.
Kleiber, M. (1961). The fire of life. An introduction to animal energetics (454 p). New York: Wiley.
Knecht, M. F., & Göransson, A. (2004). Terrestrial plants require nutrients in similar proportions. Tree physiology, 24(4), 447–460.
Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC growth charts for the United States: Methods and development. National Center for Health Statistics. Vital Health Statistics. 2002; 11(246).
Liang S, Zhao X, Liu S, Yuan W, Cheng X, Xiao Z, Zhang X, Liu Q, Cheng J, Tang H, Qu Y. A long-term Global LAnd Surface Satellite (GLASS) data-set for environmental studies. International Journal of Digital Earth. 2013 Dec 9;6(sup1):5-33.
Lumb, M. P., Mack, S., Schmieder, K. J., González, M., Bennett, M. F., Scheiman, D., et al. (2017 Oct). GaSb-based solar cells for full solar Spectrum energy harvesting. Advanced energy materials, 7(20), 1700345.
Marchetti, C. (1979 Dec 1). 1012: A check on the earth-carrying capacity for man. Energy, 4(6), 1107–1117.
Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American journal of clinical nutrition, 51(2), 241–247.
Müller, D. B. (2006 Aug 5). Stock dynamics for forecasting material flows—Case study for housing in the Netherlands. Ecological economics, 59(1), 142–156.
NASA Goddard Space Flight Center, Ocean Ecology Laboratory, Ocean Biology Processing Group. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Ocean Color Data; NASA OB.DAAC, Greenbelt, MD, USA.(n.d.)
Ort, D. R., Merchant, S. S., Alric, J., Barkan, A., Blankenship, R. E., Bock, R., et al. (2015). Redesigning photosynthesis to sustainably meet global food and bioenergy demand. Proceedings of the National Academy of Sciences, 112(28), 8529–8536.
Pearl, R., & Reed, L. J. (1920). On the rate of growth of the population of the United States since 1790 and its mathematical representation. Proceedings of the National Academy of Sciences, 6(6), 275–288.
Pimentel, D., Harman, R., Pacenza, M., Pecarsky, J., & Pimentel, M. (1994 May 1). Natural resources and an optimum human population. Population and environment, 15(5), 347–369.
Pimentel, D., Williamson, S., Alexander, C. E., Gonzalez-Pagan, O., Kontak, C., & Mulkey, S. E. (2008 Aug 1). Reducing energy inputs in the US food system. Human ecology, 36(4), 459–471.
Poorter, H., Niinemets, Ü., Poorter, L., Wright, I. J., & Villar, R. (2009). Causes and consequences of variation in leaf mass per area (LMA): A meta-analysis. The new Phytologist, 182(3), 565–588.
Preece, M., & Baines, M. (1978). A new family of mathematical models describing the human growth curve. Annals of human biology, 5(1), 1–24.
Redfield, A. C. (1958). The biological control of chemical factors in the environment. American scientist, 46(3), 230A,205–230A,221.
Revelle, R. (1976). The resources available for agriculture. Scientific American, 235(3), 164–179.
Roser, M, Ritchie, H, Ortiz-Ospina, E. World Population Growth. Published online at OurWorldInData.org . Retrieved February 7, 2020 from: https://ourworldindata.org/world-population-growth.
Sayre, N. F. (2008 Feb 5). The genesis, history, and limits of carrying capacity. Annals of the Association of American Geographers, 98(1), 120–134.
Schmitt, W. R. (1965). The planetary food potential. Annals of the new York Academy of Sciences, 118(17), 647–718.
Sender, R., Fuchs, S., & Milo, R. (2016 Aug 19). Revised estimates for the number of human and bacteria cells in the body. PLoS biology, 14(8), e1002533.
Slattery, R. A., & Ort, D. R. (2015 Jun 1). Photosynthetic energy conversion efficiency: Setting a baseline for gauging future improvements in important food and biofuel crops. Plant physiology, 168(2), 383–392.
Sterner, R. W., & Elser, J. J. (2002). Ecological stoichiometry: The biology of elements from molecules to the biosphere (439 pp). Princeton University Press: Princeton.
Stüeken EE, Kipp MA, Koehler MC, Schwieterman EW, Johnson B, Buick R. Modeling pN2 Through Geological Time: Implications for Planetary Climates and Atmospheric Biosignatures. Astrobiology. 2016; 16(12).
Susiarjo, G., Sreenath, S. N., & Vali, A. M. (2006). Optimum supportable global population: Water accounting, and dietary considerations. Environment, development and sustainability, 8(3), 313–349.
Suweis, S., Rinaldo, A., Maritan, A., & D’Odorico, P. (2013). Water-controlled wealth of nations. Proceedings of the National Academy of Sciences, 110(11), 4230–4233.
United Nations, Population Division. World Population Prospects, The 2017 Revision, Key findings and advanced tables. 2017:37.
United Nations, Department of Economic and Social Affairs, Population Division. World Population Prospects 2019, custom data acquired via website. Accessed February 7, 2020 at https://population.un.org/wpp/DataQuery/
US Geological Survey, Mineral Commodity Summaries, 2013.
US Geological Survey, Mineral Commodity Summaries, 2020.
Wiedenhofer D, Krausmann F, Haas W, Fishman T, Lauk C. (2018). Data for: Integrating material stock dynamics into economy-wide material flow accounting: concepts, modelling, and global application for 1900-2050. Mendeley Data, v1. https://doi.org/10.17632/jm37jmh55d.1
Wijffels, R. H., & Barbosa, M. J. (2010). An outlook on microalgal biofuels. Science, 329(5993), 796–799.
Yue, T.-X., Tian, Y.-Z., Liu, J.-Y., & Fan, Z.-M. (2008). Surface modeling of human carrying capacity of terrestrial ecosystems in China. Ecological modelling, 214(2), 168–180.
We thank Anne Gothmann, Forest Isbell, Paul Jackson, Steve McKelvey, and Charles Umbanhowar for helpful comments. We also thank Mari McClelland and Udeepta Chakravarty for excellent assistance with a literature review. This work benefitted from the support of the Collaborative Undergraduate Research and Inquiry program and the Gery-Kleber Chair of Economics and Management Studies at St Olaf College.
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Binder, S., Holdahl, E., Trinh, L. et al. Humanity’s Fundamental Environmental Limits. Hum Ecol 48, 235–244 (2020). https://doi.org/10.1007/s10745-020-00140-w
- Human carrying capacity
- Maximum population
- Environmental limits
- Resource constraints
- Ecological stoichiometry