Abstract

The long-term variations in solar activity are studied using the dataset comprised of sunspot number and 14C radioisotope timeseries. We use a novel S200 index to identify possible past Grand Minima (GM). The Maunder, Oort, Wolf and Spörer Minima fall in phase with the minimum of S200 index. We also show GM develop in clusters, with a separation of about 400–600 years between individual GM. Extending these found similarities to modern solar activity, it is predicted that next grand solar minimum may occur in about ~ 2090 ± 20.