Earth, Moon, and Planets

, Volume 72, Issue 1–3, pp 433–440 | Cite as

Evolution, punctuational crises and the threat to civilization

  • S. V. M. Clube


The relationship between “punctuated equilibrium” and “impact crises” is critically examined in the light of our present knowledge of asteroids and comets. It turns out that the emphasis on relatively narrow epochs associated with occasional “NEO” impacts is probably misplaced. Rather priority should be given to the wider and more frequent epochs associated with multiple “NEO” debris impacts which result in so-called “punctuational crises” afflicting the planets. These comprise the global coolings, super-Tunguska events and generally enhanced fireball flux produced by the larger orbital debris whenever an active, dormant or dead comet fragments and produces a trail. Taken as a whole and in conjunction with the target, the response function is inevitably complex. Nevertheless we broadly expect that the strength of a punctuational crisis will vary as the progenitor comet mass, the inverse dispersion of its debris and the inverse delay since fragmentation. The encounter of P/SL-9 with Jupiter may be taken as representing an extreme punctuational crisis where the dispersion and delay were exceptionally small. The more familiar crises affecting the Earth with less extreme values of dispersion and delay, which have resulted in civilization being disturbed a good many times during recent millennia, are no less important however. Indeed, the next such threat to civilization ostensibly has a roughly 1 in 4 lifetime chance. Any support for the Spaceguard programme which detracts from consideration of these punctuational crises, whatever their strength, would seem now to be peculiarly wide of the mark.


Response Function Present Knowledge Global Coolings Orbital Debris Debris Impact 
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.


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  1. Asher D.J. & Clube S.V.M., 1993, Quart.J.Roy.Astron.Soc., 34, 481.Google Scholar
  2. Bailey M.E., Clube, S.V.M., Hahn G., Napier, W.M. & Valsecchi G.B., 1994, “Hazards due to comets and asteroids” (ed. T. Gehrels et al, Univ. of Arizona Press), 479.Google Scholar
  3. Baillie, M.G.L., 1994, The Holocene, 4, 212.Google Scholar
  4. Ceplecha Z., 1992, Astron.Astrophys., 263, 361.Google Scholar
  5. Chapman C.R. & Morrison D., 1994, Nature 367, 33.Google Scholar
  6. Clube, S.V.M., 1994, “How science works in a crisis: the mass extinction debate” (ed. W.Glen, Stanford Univ. Press), 152.Google Scholar
  7. Clube, S.V.M., 1995, “The inspiration of astronomical phenomena” (ed. R. White et al), in press.Google Scholar
  8. Clube, S.V.M. & Asher, D.J., 1995, Southern Sky 9, 24.Google Scholar
  9. Clube, S.V.M. & Napier W.M., 1995, Mon.Not.Roy.Astron.Soc., submitted.Google Scholar
  10. Farinella P., 1995, These proceedings.Google Scholar
  11. Grieve R.A.F., 1989, “Catastrophes and Evolution” (ed. S.V.M. Clube, C.U.P.), 57.Google Scholar
  12. Harris A.W., 1995, Conference Summary (These proceedings).Google Scholar
  13. Holmes A., 1927, The Age of the Earth: an Introduction to Geological Ideas (Benn, London).Google Scholar
  14. Kresák L., 1981, Bull.Astron.Inst.Czechosl. 32, 19.Google Scholar
  15. Matese J.J., Whitman P.G., Innanen K.A. & Valtonen M.J., 1995, These proceedings.Google Scholar
  16. Rabinowitz D.L., Gehrels, T., Scotti J.V., McMillan R.S., Perry M.L., Wisnewski W., Larson S.M., Howell, E.S. & Mueller B.E.A., 1993, Nature 363, 704.Google Scholar
  17. Rampino M.R. & Caldeira K., 1992, Celest.Mech.Dyn.Astron. 54, 143.Google Scholar
  18. Shoemaker E.M., 1983, Ann.Rev.Earth.Planet.Sci. 11, 461.Google Scholar
  19. Spengler, O., 1991, “The Decline of the West” (Oxford Univ. Press, abridged). SteelGoogle Scholar
  20. D.I., Asher, D.J., Napier, W.M. & Clube S.V.M., 1994, “Hazards due to comets and Asteroids” (ed. T. Gehrels et al Univ. of Arizona Press), 463.Google Scholar
  21. štohl J., 1986, Asteroids, Comets, Meteors II (ed. C-I Lagerkvist et al, Univ. of Uppsala Press), 565.Google Scholar
  22. Tagliaferri E., Spalding, R., Jacobs, C., Woerden, S.P. & Erlich, A., 1994, “Hazards due to comets and asteroids” (ed. T. Gehrels et al Univ. of Arizona Press), 199.Google Scholar
  23. Wetherill G.W., 1988, Icarus 76, 1.Google Scholar
  24. Wetherill G.W., 1991, “Comets in the Post-Halley Era, I”, (ed. J.R. Newburn et al, Kluwer), 537.Google Scholar

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • S. V. M. Clube
    • 1
  1. 1.Department of PhysicsUniversity of OxfordOxfordU.K.

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