  Statistical properties of the temporal distribution of polarity reversals of
the geomagnetic field are commonly assumed to be a realization of a renewal
Poisson process with a variable rate. However, it has been recently shown that
the polarity reversals strongly depart from a local Poisson statistics, because
of temporal clustering. Such clustering arises from the presence of long-range
correlations in the underlying dynamo process. Recently achieved laboratory
dynamo also shows reversals. It is shown here that laboratory and paleomagnetic
data are both characterized by the presence of long-range correlations.
