How persistent is the present trend of the geomagntic field to decay and, possibly, to reverse?

Abstract

Recent studies provide evidence for a possible imminent change of polarity or an excursion of the geomagnetic field. In this paper we explore the possibility that the present trends are persistent, looking at the behaviour of some physical quantities of the recent geomagnetic field with particular attention to the last century. Analysis of the mean square value of the field over the last 400 years shows a linear decay that if extrapolated will be zero in around 1000 years, while if we extrapolate the field over Antarctica it will go to zero in around 300 years. The information content of the geomagnetic field has been decaying from around 1690, but began to decrease more rapidly at around 1775 and even more rapidly after 1900. An intermittent synchronicity between the exponential field decay and the increase latitudinal speed of the south geomagnetic pole with similar (decaying or growing) timescales can be interpreted as evidence for a present persistent turbulence of the geomagnetic field. From this work it emerges that the present situation is likely to persist further into the future, probably for another century, but longer predictions are not possible.