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Variations in solar luminosity and their effect on the Earth's climate

Nature volume 443, pages 161–166 (2006)Cite this article

Abstract

Variations in the Sun's total energy output (luminosity) are caused by changing dark (sunspot) and bright structures on the solar disk during the 11-year sunspot cycle. The variations measured from spacecraft since 1978 are too small to have contributed appreciably to accelerated global warming over the past 30 years. In this Review, we show that detailed analysis of these small output variations has greatly advanced our understanding of solar luminosity change, and this new understanding indicates that brightening of the Sun is unlikely to have had a significant influence on global warming since the seventeenth century. Additional climate forcing by changes in the Sun's output of ultraviolet light, and of magnetized plasmas, cannot be ruled out. The suggested mechanisms are, however, too complex to evaluate meaningfully at present.

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Figure 1: Temporal variation of total solar irradiance, as measured by radiometers on several spacecraft since 1978.
Figure 2: An image of the solar photosphere (the surface of the solar disk seen in visible light), showing the structures responsible for the TSI variations.
Figure 3: Variations in total solar irradiance.
Figure 4: Thermal disturbance caused by a sunspot, computed as a function of distance from it and depth into the Sun18.
Figure 5: Northern Hemisphere temperatures compared to model results.

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Acknowledgements

P.F. acknowledges support by NASA; T.M.L.W. was supported by the NOAA Office of Global Programs. TSI research at PMOD/WRC is supported by the Swiss National Science Foundation. Author Contributions Author order is alphabetic. P.F. and H.S. contributed the theory of solar luminosity variation, T.M.L.W. the climate modelling and C.F. the consolidated irradiance measurements.

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Authors and Affiliations

  1. Heliophysics, Inc., Nahant, Massachusetts, 01908, USA

    P. Foukal

  2. Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Dorf, Davos, CH-7260, Switzerland

    C. Fröhlich

  3. Max Planck Institute for Astrophysics, D-85741, Garching, Germany

    H. Spruit

  4. National Center for Atmospheric Research, Boulder, Colorado, 80307-3000, USA

    T. M. L. Wigley

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  1. P. Foukal
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Correspondence to H. Spruit.

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Foukal, P., Fröhlich, C., Spruit, H. et al. Variations in solar luminosity and their effect on the Earth's climate. Nature 443, 161–166 (2006). https://doi.org/10.1038/nature05072

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