Recently I posted a number of reports on the powerful correlation between solar activity cycles and historical climate change. Clearly the sun is a driver. The question that remains is what is the mechanism that drives climate.

Recently there have been a number of papers showing Danish physicist Henrik Svensmark is on the right path […]
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The latest on Svensmark’s cloud-solar-amplifier

By Prof. Fritz Vahrenholt and Dr. Sebastian Lüning
[German text translated/edited by P Gosselin]

A few years ago Henrik Svensmark described a mechanism how solar activity could change cloud cover. Was this the long-sought solar amplifier? The proposed process involves a series of steps where the sun’s magnetic field shields the earth’s atmosphere, at times more and at times less, from cosmic rays – thus acting as a modulator. The tiny galactic particles then act as seeds for condensation and cloud formation, which in turn regulate the Earth’s temperature. This mechanism allowed Svensmark to establish a correlation between solar activity and clouds. But later the curves deviated from each other in the 20th century. So indeed it turned out to be more complicated. The IPCC was elated and promptly discarded the model.

But the IPCC appears to have acted too hastily with its curt dismissal because bit by bit it is becoming increasingly clear that it is necessary to differentiate more carefully between various latitudes, cloud levels and seasons. What follows is a summary of the latest publications on the cloud-solar amplifier.

In November 2014 in the journal of Atmospheric Research M. Kancirova and K. Kudela reported on a study on the development of cloud cover and cosmic rays atop a 2634 meter mountain in Slovakia over the 1982–2010 period. Here the authors found a stable correlation between clouds and cosmic rays, even if the signal was weak. The abstract:

Cloud cover and cosmic ray variations at Lomnický štít high altitude observing site
We studied the relation of cloud cover and cosmic rays during the period 1982–2010 measured at Lomnický štít (2634 m above sea level, in the direction of 49.40°N, 20.22°E, geomagnetic vertical cut-off rigidity for cosmic ray ~ 3.85 GV). Daily means are used. It is seen that the correlations are insignificant for averaging shorter than about one year. We have found weak positive correlation for longer averaging times. Difference in distributions of cosmic ray intensity between the days with cloudless and overcast sky level at α = 0.05 is found in the data. In addition to the experiments and clarification of physical mechanisms behind the relations studied here, longer time intervals and analysis at different sites with respect to cut-off rigidity and sea/continents along with the satellite data are important for progress in understanding the cosmic ray–cloud relation questions, at least from the point of view of empirical description of the dependencies.”