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Jan-Erik Solheim, Kjell Stordahl and Ole Humlum (hereafter SSH) have recently published two articles about the relationship between the mean temperature in a solar cycle and the length of the previous solar cycle [1, 2]. For the northern hemisphere, they found a negative correlation between those two variables. A long solar cycle is followed by a solar cycle with a low temperature, and a short solar cycle is followed by a solar cycle with a high temperature. SSH call this the Previous Solar Cycle Length Model. For simplicity, in this note I refer to it as the Solar Cycle Model.
When a solar cycle has ended, its length is known, and the model can predict the mean temperature in the next solar cycle.
The temperatures fitted well with the Solar Cycle Model until the mid-1970s, but not later. The mean temperatures during the last solar cycles have been much higher than predicted by the Solar Cycle Model. The mean temperature so far in the current solar cycle 24, which has lasted for about 3.5 years, is much higher than the Solar Cycle Model predicts.