ABSTRACT Our understanding of the indirect effect of changes in solar output and feedbacks in the climate system is minimal. There is much need to refine our understanding of key natural forcing mechanisms of the climate, including solar irra-diance changes, in order to reduce uncertainty in our projections of future climate change. Through the recent years, the conflict between researchers about whether global warming is a human-generated phenomenon or a result of solar variability has raised many question marks. The aim of this work is to try to answer some of these questions by studying the possible role of some solar variability parameters such as the geomagnetic index (aa) and the sunspot number (Rz) in global temperature changes. Here, we present a correlative study of the possible contributions for the two components that may be closely associated with the climate, throughout the last 130 years (1880-2008). We compared the correlation analysis and the power spectral density (PSD) of the Rz and aa with that of the continuous records of the GT in order to get a closer look at a possible connection between them. Our results displayed that the correlations between both (aa & GST) and (Rz & GST) are +0.66 and +0.38, respectively when both parameters Rz and aa precedes by 2-3 yrs. The correlation of GST-aa is two times higher than that of GST-Rz. The GST spectrum reflected significant periods at 21.3-yr, 10.7-11.6 yr variations that observed in the considered geomagnetic and sunspot spectra.
Cite this paper
nullM. El-Borie, E. Shafik, A. Abdel-halim and S. El-Monier, "Spectral Analysis of Solar Variability and their Possible Role on the Global Warming," Journal of Environmental Protection, Vol. 1 No. 2, 2010, pp. 111-116. doi: 10.4236/jep.2010.12014.
 T. Landscheidt, “Solar Wind near Earth: Indicator of Variation in Global Temperature,” European Space Agency Special Publication 463, 2000, pp. 497-500.
S. Rahmstorf, D. Archer, D. S. Ebel, O. Eugster, J. Jouzel, D. Maraun, U. Neu, G. A. Schmidt, J. Severinghaus, A. J. Weaver and J. Zachos, “Comic Rays, Carbon Dioxide, and Climate,” EOS, Vol. 85, No. 4, 2004.
K. Lassen and E. Friis-Christensen, “Reply to Article ‘So-lar Cycle Length and Climate’ A Reference Revit by Laut,” Journal of Geophysical Research, Vol. 105, No. A12, 2000, pp. 27493-27495.
M. A. El-Borie and S. S. Al-Thoyaib, “Can We Use the Geomagnetic Index to Predict Partially the Variability in Global Mean Temperatures?” International Journal of Physical Science, Vol. 1, No. 2, October 2006, pp. 67-74.
K. Lassen and E. Friis-Christensen, “Variability of the Solar Cycle Length during the Past Five Centuries and the Apparent Association with Terrestrial Climate,” Journal of Atmospheric & Solar Terrestrial Physics, Vol. 57, No. 8, 1995, pp. 835-845.
P. Laut and J. Gundermann, “Solar Cycle Lengths and Climate: A Reference Revised,” Journal of Geophysical Research, Vol. 105, No. A12, 2000, pp. 27489-27492.
 G. N. Shah and S. Mufti, “Anti-Podal Geomagnetic Activity, Sea Surface Temperature and Long Term Solar Variations,” 29th International Cosmic Ray Conference, Pune, 2005, pp. 101-104.
R. Lockwood, R. Stamper and M. N. Wild, “A Doubling of the Sun’s Coronal Magnetic Field during the Past 100 Years,” Nature, Vol. 399, 1999, pp. 437-439.
 M. A. El-Borie, “Major Solar-Energetic Particle Fluxes: I. Comparison with the Associated Ground Level Enhancements of Cosmic Rays,” Astroparticle Physics, Vol. 19, No. 4, 2003, pp. 549-558.
M. A. El-Borie, “Major-Energetic Particle Fluxes: II. Comparison of the Interplanetary between the Three Largest High Energy Peak Flux Events 19-20/10/89, 14/7/00, and 9/11/00,” Astroparticle Physics, Vol. 19, 2003, pp. 667-677.
H. Svensmark, “Influence of Cosmic Rays on Earth’s Climate,” Physical Review Letters, Vol. 81, No. 22, 1998, pp. 5027-5030.
K. R. Lang, “The Cambridge Encyclopedia of the Sun,” Cambridge, 2001.
 P. N. Mayaud, “The aa Indices: A 100 Year Series Characterizing the Magnetic Activity,” Journal of Geophysical Research, Vol. 77, No. 34, 1972, pp. 6870-6874.
D. Valev, “Statistical Relationship between the Surface Air Temperature Anomalies and the Solar and the Geomagnetic Activity Indices,” Physics and Chemistry of the Earth, Vol. 31, No. 1-3, 2006, pp. 109-112.
 M. A. El-Borie, “North-South Asymmetry of Interplanetary Plasma and Solar Parameters,” Il Nuovo Cimento, Vol. 24C, No. 6, November 2001, pp. 843-857.
 M. A. El-Borie and S. S. Al-Thoyaib, “Galactic Cosmic Ray Modulations for Four Solar Activity Cycles,” Proceedings of 27th International Cosmic Ray Conference, Vol. 9, 2001, pp. 3780-3783.
I. G. Richardson, E. W. Cliver and H. U. Cane, “Sources of Geomagnetic Activity over the Solar Cycle: Relative Importance of Coronal Mass Ejections, High-Speed Streams, and Slow Solar Wind,” Journal of Geophysical Research, Vol. 105, No. A8, 2000, pp. 18203-18213.
M. A. El-Borie, S. S. Al-Thoyaiab and N. Al-Sayed, “The Possible Role of Solar Activity in Variability of Global Mean Temperatures,” The 2nd International Conference of Physics and Material Science, Vol. 1, 2007, pp. 302-310.