Solar variability is recorded in cores drilled from ice sheets. The flux of cosmic rays is modulated by the solar wind, the intensity of which is linked to solar eruptions. During periods of high eruptional activity, the cosmic ray flux into the atmosphere is reduced so that the production rate of radionuclides such as 14C and 10Be is diminished, and vice versa. Most radionuclides are removed from the atmosphere by wet precipitation and quasi-permanently stored in ice sheets, mainly in the Polar regions. Analysis of such ice core archives reveals extended periods of exceptionally high or low solar activity which coincide with phases of rapid climate change (Beer, 2000). The annual 10Be record “Dye 3” going back to 1423 is of special interest in this connection as it reflects the 80 to 90-year Gleissberg cycle and its relationship with climate (Beer et al., 1994).
Forecasts of natural phenomena are one of the most important aims of the natural sciences. As there are strong indications of a dependable connection between minima and maxima in the Gleissberg cycle and cool and warm periods in climate, we are confronted with the problem how to make long-range predictions of extrema in the Gleissberg cycle. Knowledge of its mean length is no real help in this respect as the cycle varies from 40 to 120 years. Fortunately, I have shown for decades that the sun's varying activity is linked to cycles in its irregular oscillation about the centre of mass of the solar system. As these cycles are connected with climate phenomena and can be computed for centuries, they offer a means to forecast consecutive minima and maxima in the Gleissberg cycle and covarying phases of cool and warm climate.
The solar dynamo theory developed by Babcock, the first still rudimentary theory of solar activity, starts from the premise that the dynamics of the magnetic sunspot cycle is driven by the sun's rotation. Yet this theory only takes into account the sun's spin momentum, related to its rotation on its axis, but not its orbital angular momentum linked to its very irregular oscillation about the centre of mass of the solar system (CM). This fundamental motion, described by Newton three centuries ago. It is regulated by the distribution of the masses of the giant planets Jupiter, Saturn, Uranus, and Neptune in space.