Space Science Reviews

, Volume 94, Issue 1–2, pp 215–230 | Cite as

Cosmic Rays, Clouds, and Climate

  • Nigel Marsh
  • Henrik Svensmark


A correlation between a global average of low cloud cover and the flux of cosmic rays incident in the atmosphere has been observed during the last solar cycle. The ionising potential of Earth bound cosmic rays are modulated by the state of the heliosphere, while clouds play an important role in the Earth's radiation budget through trapping outgoing radiation and reflecting incoming radiation. If a physical link between these two features can be established, it would provide a mechanism linking solar activity and Earth's climate. Recent satellite observations have further revealed a correlation between cosmic ray flux and low cloud top temperature. The temperature of a cloud depends on the radiation properties determined by its droplet distribution. Low clouds are warm (>273 K) and therefore consist of liquid water droplets. At typical atmospheric supersaturations (∼1%) a liquid cloud drop will only form in the presence of an aerosol, which acts as a condensation site. The droplet distribution of a cloud will then depend on the number of aerosols activated as cloud condensation nuclei (CCN) and the level of super saturation. Based on observational evidence it is argued that a mechanism to explain the cosmic ray-cloud link might be found through the role of atmospheric ionisation in aerosol production and/or growth. Observations of local aerosol increases in low cloud due to ship exhaust indicate that a small perturbation in atmospheric aerosol can have a major impact on low cloud radiative properties. Thus, a moderate influence on atmospheric aerosol distributions from cosmic ray ionisation would have a strong influence on the Earth's radiation budget. Historical evidence over the past 1000 years indicates that changes in climate have occurred in accord with variability in cosmic ray intensities. Such changes are in agreement with the sign of cloud radiative forcing associated with cosmic ray variability as estimated from satellite observations.


Atmospheric Aerosol Cloud Condensation Nucleus Droplet Distribution Liquid Water Droplet Cloud Radiative Property 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Ardanuy, P., Stowe, L.L., Gruber, A., and Weiss, M.: 1991, ‘Shortwave, longwave, and net cloudradiative forcing as determined from Nimbus-7 observations’, J. Geophys. Res. 96, 18,537.Google Scholar
  2. Geller, M.A., and Alpert, J.C.: 1980, ‘Planetary wave coupling between the troposphere and the middle atmosphere as a possible sun–weather mechanism’, J. Atmos. Sci. 37, 1197.Google Scholar
  3. Haigh, J.D.: 1996, ‘The impact of solar variability on climate’, Science 272, 981.Google Scholar
  4. Hartmann, D.L.: 1993, Radiative effects of clouds on Earth's climate, in Aerosol-Cloud-Climate Interactions, Academic Press.Google Scholar
  5. Herman, J.R., and Goldberg, R.A.: 1978, Sun, Weather, and Climate, NASA SP 426.Google Scholar
  6. Heymsfield, A.J.: 1993, Microphysical Structures of Stratiform and Cirrus Clouds, in Aerosol-Cloud-Climate Interactions, Academic Press.Google Scholar
  7. Hõrrak, U., Salm, J., and Tammet, H.: 1998, ‘Bursts of intermediate ions in atmospheric air’, J. Geophys. Res. 103, 13,909.Google Scholar
  8. King, M.D., Radke, L.F., and Hobbs, P.V.: 1993, ‘Optical properties of marine stratocumulus clouds modified by ships’, J. Geophys. Res. 98, 2729.Google Scholar
  9. Lal, D., and Peters, B.: 1967, ‘Cosmic ray produced radioactivity on the Earth’, in Encyclopaedia of Physics, Springer-Verlag, Berlin.Google Scholar
  10. Lean, J., Beer, J., and Bradley, R.: 1995, ‘Reconstruction of solar irradiance since 1610: Implications for climate change’, Geophys. Res. Lett. 22, 3195.Google Scholar
  11. Lockwood, M., Stamper, R., and Wild M.N.: 1999, ‘A doubling of the Sun's coronal magnetic field during the past 100 years’, Nature 399, 437.Google Scholar
  12. Lockwood, M. and Stamper, R.: 1999, ‘Long-term drift of the coronal source magnetic flux and the total solar irradiance’, Geophys. Res. Lett. 26, 2461.Google Scholar
  13. Marsh, N.D. and Svensmark, H.: 2000, ‘Low cloud properties influenced by solar activity’, Phys. Rev. Lett., submitted.Google Scholar
  14. Neher, H.V.: 1971, ‘Cosmic-Rays at high latitudes and altitudes covering four solar maxima’, J. Geophys. Res. 76, 1637.Google Scholar
  15. Ney, E.R.: 1959, ‘Cosmic radiation and the weather’, Nature 183, 451.Google Scholar
  16. Ohring, G., and Clapp, P.F.: 1980, ‘The effect of changes in cloud amount on the net radiation at the top of the atmosphere’, J. Atmos. Sci. 37, 447.Google Scholar
  17. Pruppacher, H.R., and Klett, J.D.: 1997, Microphysics of Clouds and Precipitation, Kluwer, Dordrecht.Google Scholar
  18. Ramanathan, V., et al.: 1989, ‘Results from the Earth's radiation budget experiment’, Science 243, 57.Google Scholar
  19. Rossow, W.B., and Schiffer, R.A.: 1991, ‘ISCCP Cloud Data Products’, Bull. Am. Met. Soc. 72, 2.Google Scholar
  20. Rossow, W.B., Walker, A.W., Beuschel, D.E., and Roiter, M.D.: 1996, International Satellite Cloud Climatology Project (ISCCP): Documentation of New Cloud Datasets, World Meteorological Organization, Geneva.Google Scholar
  21. Schiffer, R.A., and Rossow, W.B.: 1983 ‘The International Satellite Cloud Climatology Project (ISCCP): The first project of the World Climate Research Programme’, Bull. Am. Met. Soc. 64, 779.Google Scholar
  22. Schiffer, R.A., and Rossow, W.B.: 1985, ‘ISCCP Global Radiance Data Set: A New Resource for Climate Research’, Bull. Am. Met. Soc. 66, 1498.Google Scholar
  23. Shindell, D., Rind, D., Balabhandran, N., Lean, J., and Lonergan, P.: 1999, ‘Solar cycle variability, ozone, and climate’, Science 284, 305.Google Scholar
  24. Stowe, L.L., Wellemayer, C.G., Eck, T.F., Yeh, H.Y.M., and the Nimbus-7 team: 1988, J. Clim. 1, 445.Google Scholar
  25. Svensmark, H., and Friis-Christensen, E.: 1997, ‘Variation of Cosmic Ray Flux and Global Cloud Coverage – A Missing Link in Solar-Climate Relationships’, J. Atm. Sol. Terr. Phys. 59, 1225.Google Scholar
  26. Svensmark, H.: 1998, ‘Influence of cosmic rays on climate’, Phys. Rev. Lett. 81, 5027.Google Scholar
  27. Turco, R.P., Zhao, J.-X., and Yu, F.: 1998, ‘A new source of tropospheric aerosols: Ion-ion recombination’, Geophys. Res. Lett. 25, 635.Google Scholar
  28. Viggiano, A.A., and Arnold, F.: 1995, Ion Chemistry and Composition of the Atmosphere, in Handbook of Atmospheric Electrodynamics, CRC Press.Google Scholar
  29. Weng, F., and Grody, N.C.: 1994, J. Geophys. Res. 99, 25,535.Google Scholar
  30. Yu, F., and Turco, R.P.: 2000, ‘Ultrafine aerosol formation via ion-mediated nucleation’, Geophys. Res. Lett. 27, 883.Google Scholar

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Nigel Marsh
    • 1
    • 2
  • Henrik Svensmark
    • 1
    • 2
  1. 1.Danish Space Research InstituteDenmark
  2. 2.CopenhagenDenmark

Personalised recommendations