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Ecological Modelling
Volume 222, Issue 12, 24 June 2011, Pages 2019-2026
doi:10.1016/j.ecolmodel.2011.03.030 | How to Cite or Link Using DOI
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Harvesting the sun: New estimations of the maximum population of planet Earth
Siegfried Francka, Corresponding Author Contact Information, E-mail The Corresponding Author, Werner von Bloha, Christoph Müllera, Alberte Bondeaua, B. Sakschewskib
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a Potsdam Institute for Climate Impact Research (PIK), Research Domains Earth System Analysis and Climate Impacts & Vulnerabilities, Telegraphenberg, P.O. Box 601203, D-14412 Potsdam, Germany
b Universität Potsdam, Institut für Biochemie und Biologie, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam, Germany
Received 2 December 2010; revised 24 March 2011; Accepted 25 March 2011. Available online 18 April 2011.
Abstract
The maximum population, also called Earth's carrying capacity, is the maximum number of people that can live on the food and other resources available on planet Earth.
Previous investigations estimated the maximum carrying capacity as large as about 1 trillion people under the assumption that photosynthesis is the limiting process. Here we use a present state-of-the-art dynamic global vegetation model with managed planetary land surface, Lund-Potsdam-Jena managed Land (LPJmL), to calculate the yields of the most productive crops on a global 0.5° × 0.5° grid. Using the 2005 crop distribution the model predicts total harvested calories that are sufficient for the nutrition of 11.4 billion people. We define scenarios where humankind uses the whole land area for agriculture, saves the rain forests and the boreal evergreen forests or cultivates only pasture to feed animals. Every scenario is run in an extreme version with no allowance for urban and recreational needs and in two soft versions with a certain area per person for non-agricultural use. We find that there are natural limits of the maximum carrying capacity which are independent of any increase in agricultural productivity, if non-agricultural land use is accounted for. Using all land planet Earth can sustain 282 billion people. The save-forests-scenario yields 150 billion people. The scenario that cultivates only pasture to feed animals yields 96 billion people. Nevertheless, we should always have in mind that all our calculated numbers for the carrying capacity refer to extreme scenarios where
humankind may only vegetate on this planet. Our numbers are considerably higher than the general median estimate of upper bounds of human population found in the literature in the order of 10 billion.
http://www.sciencedirect.com/science...04380011001670
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