Hi Roxana,

> Has anybody mentioned the correlation with
> increased solar storm activity?


I don't think anyone has mentioned it this time. A couple of points about solar activity:

First, as reported by J.D. Haigh [1], there is a greater relative variation in the ultraviolet flux than in the total solar flux. This causes extra ozone production during peaks in the sunspot cycle which, by absorbing some of the radiation before it reaches troposphere, significantly reduces the global mean surface troposphere forcing.

Second, three studies [2,3,4] estimated the globally and annually averaged radiative forcing due to solar variability, each approaching from a slightly different angle. Although there are some notable differences between the three reconstructions, they all agree in giving the minimum solar luminosity around 1880 and a maximum in the 1930s or 1950s.

A model that assumes variation of solar luminosity to be the only factor that has caused climatic change during the 20th century [5] is found internally inconsistent, because it assumes that the climate responds to radiative forcing by the sun, but not to the radiative forcing due to well-mixed greenhouse gases (GHG).

Building on this model, Kelly and Wigley [6] analysed the effect on combined GHG and aerosol forcing and solar variability. They deduced that GHG+aerosol increases explain 45-48% of the observed temperature variation since 1860, and that solar variability only explains 13-19%. This is supported by a statistical analysis of temperature and solar variation by Schönwiese et al [7], who conclude that solar variability explains at most 15-20% of the global mean temperature changes during the 20th century.



References:


[1] Haigh, J.D. (1994) Nature , 370 , 544-546
[2] Lean et al. (1995) , Geophysical Research Letters , 22 , 3195-3198
[3] Solanski and Fligge (1998) Geophysical Research Letters , 25 , 341-344
[4] Hoyt and Schatten (1993) Journal of Geophysical Research , 98 , 18895- 18906
[5] Friis-Christensen and Lassen (1991) Science , 254 , 698-700
[6] Kelly and Wigley (1992) Nature , 360 , 328-330
[7] Schönwiese et al. (1994) Climatic Change , 27 , 259-281



Regards,
Tommi

"In this house, we obey the laws of thermodynamics!"
-Homer J. Simpson