A Probabilistic Assessment of the Next Geomagnetic Reversal

Abstract

Deterministic forecasts for the next geomagnetic reversal are not feasible due to large uncertainties in the present‐day state of the Earth's core. A more practical approach relies on probabilistic assessments using paleomagnetic observations to characterize the amplitude of fluctuations in the geomagnetic dipole. We use paleomagnetic observations for the past 2 Myr to construct a stochastic model for the axial dipole field and apply well‐established methods to evaluate the probability of the next geomagnetic reversal as a function of time. For a present‐day axial dipole moment of 7.6 × 1022 A m2, the probability of the dipole entering a reversed state is less than 2% after 20 kyr. This probability rises to 11% after 50 kyr. An imminent geomagnetic reversal is not supported by paleomagnetic observations. The current rate of decline in the dipole moment is unusual but within the natural variability predicted by the stochastic model.

Variability of Millennial‐Scale Trends in the Geomagnetic Axial Dipole

“…The model predicts that the dipole moment could vanish over the next 20 kyr with a 2% probability. A remarkably similar prediction was obtained by different means using a solution of the backward Fokker-Planck equation (Buffett & Davis, 2018). We establish these results by first showing how a stochastic model can be used to characterize the variability in the dipole trend as a function of window length.…”

“…A remarkably similar prediction was made using a solution of the backward Fokker‐Planck equation (Buffett & Davis, ). This agreement may be surprising at first glance because the solution in has the form of a purely diffusive process with no dependence on the drift term (e.g., Shcherbakov & Fabian, ).…”

A comprehensive model for the kyr and Myr timescales of Earth's axial magnetic dipole field

“…Representative variations in D, however, have a small influence on the statistical properties of solutions of the SDE (Eq. 1); see Buffett and Matsui (2015). The function v is called the "drift" and is derived from a double-well potential, U (x) = −v(x).…”

“…This assumption is reasonable when describing the dipole field on the Myr timescale, but is not valid on a shorter timescale of thousands of years. Buffett and Matsui (2015) derived an extension of the B13 model to extend it to timescales of thousands of years by adding a time-correlated noise process. An extension of B13 to represent changes in reversal rates over the past 150 Myr is considered by Morzfeld et al (2018).…”

“…An extension of B13 to represent changes in reversal rates over the past 150 Myr is considered by Morzfeld et al (2018). Its use for predicting the probability of an imminent reversal of Earth's dipole is described by Morzfeld et al (2017) and by Buffett and Davis (2018). The B13 model is also discussed by Meduri and Wicht (2016), Buffett et al (2014), and Buffett (2015).…”