Curated by RSF Research Staff
A disturbance in the field
The Earth’s magnetic field appears to be shifting and geologists don’t know why.
Like most spinning systems, such as stars and planets, the Earth’s magnetic field is assumed to be generated through the motion of electrically conducting fluids – such as a liquid iron core as is thought to be the case for the Earth. All being well, in a perfect idealized ‘physics’ world, the magnetic field would align with the axis of spin. However, the reality is that the Earth’s magnetic field is aligned at an 11-degree angle to the spin axis, hovering somewhere over Canada. The exact location is variable and over the last 180 years the magnetic north pole has been migrating northwestward with movements of up to 25 miles per year.
Variation of the poles is normal and, in some cases, can result in complete reversal of the poles. This can be seen in the magnetic fingerprints stored in ancient rocks, which show that the poles have flipped every 200,000 to 300,00 years for the last 20 million years. The last flip occurred around 780,000 years ago so some say we are well over due for a flip! If a flip did occur, then our north compass would point towards the south pole and vice versa. This could result in some confusion, especially for animals with internal compasses, such as birds. As well, when a flip has occurred in the past it has been associated with a temporary weakening of the field, which would remove the capabilities of Earth’s protective shield exposing us to increased levels of radiation. Read more here.
Understanding the magnetic field in all its complexities has been progressing with the continuous development of computer simulations – however it still has a long way to go in furthering our understanding and reaching a satisfactory predictive model.
The World Magnetic Model (WMM) utilizes these computer simulations to spatially represent the Earth’s magnetic field. All modern navigation systems rely on it – from the systems that steer ships at sea to Google maps on smart phones. Its accuracy is paramount and is therefore updated every 5 years to account for the latest variations. The next update was scheduled for 2020, however, recently the magnetic field has been changing so rapidly and erratically that it has to be updated now – with the update set for the end of this month!
By: Amira Val Baker, RSF research scientist