Space Science Reviews

, Volume 125, Issue 1, pp 95–109

What do Cosmogenic Isotopes Tell us About Past Solar Forcing of Climate?

Article

DOI: 10.1007/s11214-006-9049-2

Cite this article as:
Lockwood, M. Space Sci Rev (2006) 125: 95. doi:10.1007/s11214-006-9049-2

Abstract

In paleoclimate studies, cosmogenic isotopes are frequently used as proxy indicators of past variations in solar irradiance on centennial and millennial timescales. These isotopes are spallation products of galactic cosmic rays (GCRs) impacting Earth's atmosphere, which are deposited and stored in terrestrial reservoirs such as ice sheets, ocean sediments and tree trunks. On timescales shorter than the variations in the geomagnetic field, they are modulated by the heliosphere and thus they are, strictly speaking, an index of heliospheric variability rather than one of solar variability. Strong evidence of climate variations associated with the production (as opposed to the deposition) of these isotopes is emerging. This raises a vital question: do cosmic rays have a direct influence on climate or are they a good proxy indicator for another factor that does (such as the total or spectral solar irradiance)? The former possibility raises further questions about the possible growth of air ions generated by cosmic rays into cloud condensation nuclei and/or the modulation of the global thunderstorm electric circuit. The latter possibility requires new understanding about the required relationship between the heliospheric magnetic fields that scatter cosmic rays and the photospheric magnetic fields which modulate solar irradiance.

Keywords

galactic cosmic rays total solar irradiance cosmogenic isotopes paleoclimate changes 

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  1. 1.Rutherford Appleton LaboratorySpace Science and Technology Department, Chilton, DidcotOxfordshireUK
  2. 2.University of SouthamptonHighfieldUK

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