It was observed by Danish physicists (Fris Christensen and Lassen) that global temperature correlated very well with sunspot count. This was put forward as important in the global warming debate. However the idea never made it into the IPCC models. This was because the direct heating effect of the sun (total solar irradiation, or TSI) had been measured, and shown to vary only a little with sun spots.
Because TSI is near constant, the sun has been considered a ‘constant’ in the IPCC models. One of the results of this is that the temperature increase has been ‘attributed’ to increasing atmospheric CO2 and the ‘feedback effects’ of water vapour. (Water vapour is a bigger greenhouse gas than CO2).
However, some recent scientific work is showing that the sun has other climatic effects. In addition to TSI, the sun also has magnetic and cosmic effects. These vary much more than TSI, with sunspot activity.
Jasper Kirkby leads a team of about 50 scientists in a project called ‘CLOUD’. They are looking into one of these mechanisms. They are investigating how the sun’s cosmic effects might affect the formation of clouds.
Here’s a couple of pieces from the article:
‘ … “We are trying to understand what the connection is – if any – between a cosmic ray going through the atmosphere and a change in clouds,” Kirkby explains. A cosmic ray is a sub-atomic particle created by supernovae explosions somewhere in the Milky Way. He adds, perhaps stating the obvious, that “it is clearly not as simple as that”. There is no doubt that CLOUD could have important ramifications. If some of the theories Kirkby and his team are testing are proven, they could suggest that the natural, rather than man-made, component of current climate change is greater than previously thought. …’
‘… Satellite measurements show a correlation between the intensity of cosmic rays, which varies with the sunspot cycle, and the amount of cloud cover. It is complex science but the aim of CLOUD is to gain an understanding of this apparent connection. “As far as I’m concerned,” Kirkby continues, “until this natural contribution to climate change is well understood there will be a big uncertainty as to what is going on with mankind’s contribution.”…’
And a link to the whole article: