Climatic Change

, Volume 95, Issue 3–4, pp 405–431 | Cite as

Climatic constraints on maximum levels of human metabolic activity and their relation to human evolution and global change

  • Axel KleidonEmail author
Open Access


No matter what humans do, their levels of metabolic activity are linked to the climatic conditions of the land surface. On the one hand, the productivity of the terrestrial biosphere provides the source of chemical free energy to drive human metabolic activity. On the other hand, human metabolic activity results in the generation of heat within the body. The release of that heat to the surrounding environment is potentially constrained by the climatic conditions at the land surface. Both of these factors are intimately linked to climate: Climatic constraints act upon the productivity of the terrestrial biosphere and thereby the source of free energy, and the climatic conditions near the surface constrain the loss of heat from the human body to its surrounding environment. These two constraints are associated with a fundamental trade-off, which should result in a distinct maximum in possible levels of human metabolic activity for certain climatic conditions. For present-day conditions, tropical regions are highly productive and provide a high supply rate of free energy. But the tropics are also generally warm and humid, resulting in a low ability to loose heat, especially during daylight. Contrary, polar regions are much less productive, but allow for much higher levels of heat loss to the environment. This trade-off should therefore result in an optimum latitude (and altitude) at which the climatic environment allows humans to be metabolically most active and perform maximum levels of physical work. Both of these constraints are affected by the concentration of atmospheric carbon dioxide pCO 2, but in contrary ways, so that I further hypothesize that an optimum concentration of pCO 2 exists and that the optimum latitude shifts with pCO 2. I evaluate these three hypotheses with model simulations of an Earth system model of intermediate complexity which includes expressions for the two constraints on maximum possible levels of human metabolic activity. This model is used to perform model simulations for the present-day and sensitivity experiments to different levels of pCO 2. The model simulations support the three hypotheses and quantify the conditions under which these apply. Although the quantification of these constraints on human metabolic activity is grossly simplified in the approach taken here, the predictions following from this approach are consistent with the geographic locations of where higher civilizations first emerged. Applied to past climatic changes, this perspective can explain why major evolutionary events in human evolutionary history took place at times of global cooling. I conclude that the quantification of these constraints on human metabolic activity is a meaningful and quantitative measure of the “human habitability” of the Earth’s climate. When anthropogenic climate change is viewed from this perspective, an important implication is that global warming is likely to lead to environmental conditions less suitable for human metabolic activity in their natural environment (and for large mammals in general) due to a lower ability to loose heat.


Heat Loss Supply Rate Earth System Model High Civilization Climatic Environment 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. Allman JM (1999) Evolving brains. Scientific American Library, New YorkGoogle Scholar
  2. Campbell GS, Norman JM (1998) An introduction to environmental biophysics, 2nd edn. Springer Publishers, New York, NYGoogle Scholar
  3. Cerling TE, Harris JM, MacFadden BJ, Leakey MG, Quade J, Eisenmann V, Ehleringer JR (1997) Global vegetation change through the Miocene/Pliocene boundary. Nature 389:153–158CrossRefGoogle Scholar
  4. Chaisson EJ (2001) Cosmic evolution: rise of complexity in nature. Harvard University Press, Cambridge, MAGoogle Scholar
  5. Cramer W, Bondeau A, Woodward FI, Prentice IC, Betts RA, Brovkin V, Cox PM, Fischer V, Foley JA, Friend AD, Kucharik C, Lomas MR, Ramankutty N, Sitch S, Smith B, White A, Young-Molling C (2001) Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models. Glob Chang Biol 7:357–373CrossRefGoogle Scholar
  6. Crowley TJ, North GR (1991) Paleoclimatolgy. Oxford University Press, New YorkGoogle Scholar
  7. Diamond J (1997) Guns, germs, and steel: the fates of human societies. Norton and Company, Inc., New York, NYGoogle Scholar
  8. Field CB, Behrenfeld MJ, Randerson JT, Falkowski P (1998) Primary production of the biosphere: integrating terrestrial and oceanic components. Science 281:237–240CrossRefGoogle Scholar
  9. Fraedrich K, Jansen H, Kirk E, Luksch U, Lunkeit F (2005a) The planet simulator: towards a user friendly model. Z Meteorol 14:299–304CrossRefGoogle Scholar
  10. Fraedrich K, Jansen H, Kirk E, Lunkeit F (2005b) The planet simulator: green planet and desert world. Z Meteorol 14:305–314CrossRefGoogle Scholar
  11. Hammond KA, Diamond J (1997) Maximal sustained energy budgets in humans and animals. Nature 386:457–462CrossRefGoogle Scholar
  12. Haug GA, Guenther D, Peterson LC, Sigman DM, Hughen KA, Aeschlimann B (2003) Climate and the collapse of Maya civilization. Science 299:1731–1735CrossRefGoogle Scholar
  13. Huntington E (1915) Civilization and climate. Yale University Press, New Haven, ConnGoogle Scholar
  14. Imhoff ML, Bounoua L, Ricketts T, Loucks C, Harriss R, Lawrence WT (2004) Global patterns in human consumption of net primary production’. Nature 429:870–873CrossRefGoogle Scholar
  15. IPCC (2001) Climate change 2001: the scientific basis. Contribution of working group I to the third assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USAGoogle Scholar
  16. Kleidon A (2002) Testing the effect of life on earth’s functioning: how Gaian is the earth system? Clim Change 66:271–319CrossRefGoogle Scholar
  17. Kleidon A (2004) Beyond Gaia: thermodynamics of life and earth system functioning. Clim Change 66:271–319CrossRefGoogle Scholar
  18. Kleidon A (2006) The climate sensitivity to human appropriation of vegetation productivity and its thermodynamic characterization. Glob Planet Change 54:109–127CrossRefGoogle Scholar
  19. Kleidon A, Lorenz RD (eds) (2005) Non-equilibrium thermodynamics and the production of entropy: life, earth, and beyond. Springer Verlag, Heidelberg, GermanyGoogle Scholar
  20. Kothavala Z, Oglesby RJ, Saltzman B (1999) Sensitivity of equilibrium surface temperature of CCM3 to systematic changes in atmospheric CO2. Geophys Res Lett 26:209–212CrossRefGoogle Scholar
  21. Lamb HH (1982) Climate, history and the modern world. Routledge, London, New YorkGoogle Scholar
  22. Larcher W (1995) Plant physiological ecology, 3rd edn. Springer Publishers, New York, NYGoogle Scholar
  23. Lear CH, Elderfield H, Wilson PA (2000) Cenozoic deep-sea temperatures and global ice volumes from Mg/Ca in benthic foraminiferal calcite. Science 287:269–272CrossRefGoogle Scholar
  24. Long SP, Ainsworth EA, Leakey ADB, Noesberger J, Ort DR (2006) Food for thought: lower-than-expected crop yield stimulation with rising CO2 concentrations. Science 312:1918–1921CrossRefGoogle Scholar
  25. Lunkeit F, Fraedrich K, Jansen H, Kirk E, Kleidon A, Luksch U (2004) Planet simulator reference manual. Available at
  26. Monteith JL, Huda AKS, Midya D (1989) RESCAP: a resource capture model for sorghum and pearl millet. In: Virmani SM, Tandon HLS, Alagarswamy G (eds) Modelling the growth and development of sorghum and pearl millet, Vol 12. ICRISAT Research Bulletin, Patancheru, India, pp 30–34Google Scholar
  27. Odum HT (1988) Self-organization, transformity, and information. Science 242:1132–1139CrossRefGoogle Scholar
  28. Oglesby RJ, Saltzman B (1992) Equilibrium climate statistics of a general circulation model as a function of atmospheric carbon dioxide. I - Geographic distributions of primary variables. J Clim 5:66–92CrossRefGoogle Scholar
  29. Ozawa H, Ohmura A, Lorenz RD, Pujol T (2003) The second law of thermodynamics and the global climate system – a review of the maximum entropy production principle. Rev Geophys 41:1018CrossRefGoogle Scholar
  30. Pearson PN, Palmer MR (2000) Atmospheric carbon dioxide concentrations over the past 60 million years. Nature 406:695–699CrossRefGoogle Scholar
  31. Peixoto JP, Oort AH (1992) Physics of climate. American Institute of Physics, New York, NYGoogle Scholar
  32. Petit JR, Jouzel J, Raynaud D, Barkov NI, Barnola J-M, Basile I, Bender M, Chappellaz J, Davis M, Delaygue G, Kotlyakov VM, Legrand M, Lipenkov VY, Lorius C, Pepin L, Ritz C, Saltzman E, Stievenard M (1999) Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399:429–439CrossRefGoogle Scholar
  33. Ritter C (1852) Einleitung zur Allgemeinen vergleichenden Geographie und Abhandlungen zur Begründung einer mehr wissenschaftlichen Behandlung der Erdkunde. G. Reimer, BerlinGoogle Scholar
  34. Rojstaczer S, Sterling SM, Moore NJ (2001) Human appropriation of photosynthesis products. Science 294:2549–2552CrossRefGoogle Scholar
  35. Sage RF (1995) Was low atmospheric CO2 during the Pleistocene a limiting factor for the origin of agriculture? Glob Chang Biol 1:93–106CrossRefGoogle Scholar
  36. Schrödinger E (1944) What is life? The physical aspect of the living cell. Cambridge University Press, Cambridge, UKGoogle Scholar
  37. Schwartzman DW, Middendorf G (2000) Biospheric cooling and the emergence of intelligence. In: Lemarchand G, Meech K (eds) A new era in bioastronomy, Vol 213. ASP Conference Series, pp 425–429Google Scholar
  38. Smil V (1999) Energies - an illustrated guide to the biosphere and civilization. MIT Press, Cambridge, MassachusettsGoogle Scholar
  39. Vitousek PM, Ehrlich PR, Ehrlich AH, Matson PA (1986) Human appropriation of the products of photosynthesis. Bioscience 36:368–373CrossRefGoogle Scholar
  40. Vitousek PM, Mooney HA, Lubchenco J, Melillo JM (1997) Human domination of earth’s ecosystems. Science 277:494–499CrossRefGoogle Scholar
  41. Vrba ES (1995) The fossil record of African Antelopes (Mammalia, Bovidae) in relation to human evolution and paleoclimate. In: Vrba ES, Denton GH, Partridge TC, Burckle LH (eds) Paleoclimate and evolution, with emphasis on human origins. Yale University Press, New Haven, CT, and London, UK, pp 385–424Google Scholar
  42. Vrba ES, Denton GH, Partridge TC, Burckle LH (eds) (1995) Paleoclimate and evolution, with emphasis on human origins. Yale University Press, New Haven, CT, and London, UKGoogle Scholar
  43. Zachos J, Pagani M, Sloan L, Thomas E, Billups K (2001) Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292:686–693CrossRefGoogle Scholar
  44. Zotin AI (1984) Bioenergetic trends of evolutionary progress of organisms. In: Lamprecht I, Zotin AI (eds) Thermodynamics and regulation of biological processes. de Gruyter, Berlin, New York, pp 451–458Google Scholar

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Authors and Affiliations

  1. 1.Biospheric Theory and Modelling GroupMax-Planck-Institut für BiogeochemieJenaGermany

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