More details concerning our previous post on the prediction of Abdussamatov of a minimum in solar activity, and hence global temperature, in 2040 can be found here. The plot above, courtesy of Dr. Abdussamatov, shows sunspots versus year along with the secular average with a prediction for a minimum in 2040. As far as we understand it, he is predicting another Maunder Minimum. The variations of the 11 year cycle of sunspots on about a 90 year scale is call the Gleissberg period which can be seen in the graph above. See this for a more detailed discussion of the relationship between sunspots and global temperature.
Beckman and Mahoney provide a nice discussion of the debate between the greenhouse gas advocates and the solar advocates for the cause of global warming. Here is the key paragraph:
One should be wary of jumping to conclusions about the role of greenhouse gases in our atmosphere in procuring a generalized warming of the Earth, given the great complexity of physical processes inherent in the reaction of the atmosphere-ocean system to a change in atmospheric transparency, knowing that such a change is in fact occurring as a result of the emission of gases in industry and transport. To this area of doubt the advocates of solar global warming have been able to add their element of confusion. Maybe we are experiencing a steady rise in the solar constant, accompanying a similar rise in solar magnetic variability, and maybe the greenhouse effect is not the main agent, or even a cause, of global warming. The novelty of the use of the Maunder Minimum in this context is the hypothesis that the time-scale associated with any change may be of order hundreds rather than tens of years, which would be the scale for changes directly linked to individual 11- or 22-year cycles.
