Advertisement

Climatic Change

, Volume 52, Issue 4, pp 383–389 | Cite as

Testing the Effect of Life on Earth's Functioning: How Gaian Is the Earth System?

  • Axel Kleidon
Article

Abstract

The Gaia hypothesis of Lovelock states that life regulates Earth's functioning for its own benefit, maintaining habitable, or even optimum conditions for life. But what is beneficial? What is good for one species, may be bad for another. Problems associated with this important, but ill-defined hypothesis make it difficult to test. In order to address these problems and make the concept of Gaia testable, I give a precise definition of terms. Based on these definitions, I put forward four null hypotheses, describing increasing beneficial effects of life on the conditions of Earth, ranging from an ‘Antigaian’ to an ‘optimising Gaian’ null hypothesis. I list some indications for rejection of all but one hypothesis, and conclude that life has indeed a strong tendency to affect Earth in a way which enhances the overall benefit (that is, carbon uptake). However, this does not imply that the biota regulates Earth's environment for its own benefit.

Keywords

Beneficial Effect Null Hypothesis Optimum Condition Earth System Strong Tendency 
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.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Betts, R. A.: 1999, ‘Self-Beneficial Effects of Vegetation on Climate in an Ocean-Atmosphere General Circulation Model’, Geophys. Res. Lett. 26, 1457–1460.Google Scholar
  2. Fraedrich, K., Kleidon, A., and Lunkeit, F.: 1999, ‘A Green Planet versus a DesertWorld: Estimating the Effect of Vegetation Extremes on the Atmosphere’, J. Climate 12, 3156–3163.Google Scholar
  3. Kirchner, J. W.: 1989, ‘The Gaia Hypothesis: Can It Be Tested?’, Rev. Geophys. 27, 223–235.Google Scholar
  4. Kleidon, A., Fraedrich, K., and Heimann, M.: 2000, ‘A Green Planet versus a Desert World: Estimating the Maximum Effect of Vegetation on Land Surface Climate’, Clim. Change 44, 471–493.Google Scholar
  5. Kleidon, A. and Heimann, M.: 1998, ‘Optimised Rooting Depth and Its Impacts on the Simulated Climate of an Atmospheric General Circulation Model’, Geophys. Res. Lett. 25, 345–348.Google Scholar
  6. Lenton, T. M.: 1998, ‘Gaia and Natural Selection’, Nature 394, 439–447.Google Scholar
  7. Lovelock, J. E. and Margulis, L.: 1974, ‘Atmospheric Homeostasis by and for the Biosphere: The Gaia Hypothesis’, Tellus 26, 2–10.Google Scholar
  8. Lovelock, J. E.: 1989, ‘Geophysiology, the Science of Gaia’, Rev. Geophys. 27, 215–222.Google Scholar
  9. Roeckner, E., Arpe, K., Bengtsson, L., Christoph, M., Claussen, M., Dümenil, L., Esch, M., Giorgetta, M., Schlese, U., Schulzweida, U.: 1996, The Atmospheric General Circulation Model ECHAM-4: Model Description and Simulation of Present-Day Climate, Report 218, Max-Planck-Institut für Meteorologie, Hamburg, Germany, ISSN 0937-1060.Google Scholar
  10. Schneider, S. H.: 1987, ‘Gaia: A Goddess of the Earth?’, in 1988 Yearbook of Science and the Future, Encyclopaedia Britannica, Encyclopaedia Britannica Inc., Chicago, pp. 29–43.Google Scholar
  11. Schneider, S. H. and Boston, P. J. (eds.): 1991, Scientists on Gaia, MIT Press, Cambridge, Mass.Google Scholar
  12. Schrödinger, E.: 1944, What is Life? The Physical Aspect of the Living Cell, The University Press, Cambridge, U.K.Google Scholar
  13. Volk, T.: 1998, Gaia's Body: Toward a Physiology of Earth, Springer Verlag, New York. (Received 12 October 2000; in revised form 25 July 2001)Google Scholar

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Axel Kleidon
    • 1
  1. 1.Department of GeographyUniversity of MarylandCollege ParkU.S.A.

Personalised recommendations