The magnetic field is generated within the Earth by a fluid outer core of iron, nickel and other metals that creates electric currents, which in turn produce magnetic fields. The magnetic field is strong enough to shield the Earth from solar winds and cosmic radiation. The fact that it changes is well known; the reasons why have remained a mystery. Now this mystery may be a little closer to being solved.
Scientists at Oregon State University have identified patterns in the Earth’s magnetic field that evolve on the order of a thousand years, providing new insight into how the field works and adding a measure of predictability to changes in the field not previously known. In spite of its importance, many questions remain unanswered about why and how these changes occur. The simplest form of magnetic field comes from a dipole: a pair of equally and oppositely charged poles, like a bar magnet. The Earth is not a perfect dipole, and these imperfections can be seen in the historical record.
As it turns out, the magnetic field is somewhat less complicated than we thought. It is a fairly simple oscillation that appears to result from geomagnetic intensity variations at just a few recurrent locations around the world, with large spatial impacts. While scientists are well aware of the pattern of reversals in the Earth’s magnetic field, a secondary pattern of geomagnetic ‘wobble’ within periods of stable polarity, known as paleomagnetic secular variation, or PSV, proved to be the key to understanding some geomagnetic changes occur.
Source: Oregon State University (OSU)
"A 17,000 yr paleomagnetic secular variation record from the southeast Alaskan margin: Regional and global correlations" - M. H. Walczak et al. - Earth and Planetary Science Letters - 2017 - https://doi.org/10.1016/j.epsl.2017.05.022
Walczak and Stoner are in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences. Other authors on the study are Alan Mix, also of OSU; John Jaeger, Gillian Rosen and James Channell of the University of Florida; David Heslop of Australian National University; and Chuang Xuan of the University of Southampton.
Credit for image featured at top of page: NASA/Goddard