Earth’s magnetic field is drifting towards west.

The magnetic field of our planet is generated deep down in its core so the direct study was never an option. As a result, scientists had to rely on the shockwaves that travel through Earth in case of earthquakes. By making use of this information, they figured out a most likely structure of the core that produces this field. A 2,000-kilometer layer of molten nickel, iron and, other metals surround the inner core of the planet.

It is commonly known as the outer core. Inside it is the solid inner core which is located right at the heart of the Earth. Most of it is made up of heated iron which is as hot as the surface of the Sun. Despite that, the metal stays in the solid form due to the presence of immense pressure of the gravity.

Convection currents are produced when cooler matter sinks while the warmer molten matter rises as it is less dense. This flow of iron generates electric currents which lead to the formation of magnetic fields. A self-sustaining loop called ‘Geodynamo’ is formed as charged metal particles pass through these fields to create an electric current of their own. The spinning motion of the Earth gives birth to the Coriolis force which causes swirling whirlpools. These spirals align separate magnetic fields in some sort of an arrangement where all of them are in the same direction. The combined effect of all of them is what we call the Earth’s magnetic field.

Humans have observed a westward movement of the Earth’s magnetic field ever since they began studying it. The reasons for this movement are unknown but the latest hypothesis may solve this riddle. According to a theory, some slow waves, known as ‘Rossby’ waves, in the outer core are responsible for this deviation. These waves arise in rotating fluids and are found in the atmosphere and the oceans of the Earth. Similarly, they are experienced at Jupiter and the Sun. That’s the reason, they are commonly called the ‘Planetary’ waves. The oceanic and atmospheric Rossby waves rotate westwards while the movement of these waves in the Earth’s core is eastwards. O.P. Bardsley, a student of doctoral at the University of Cambridge and the author of this new study described it in the following words:

“Rossby waves in the core are a bit like turning atmospheric Rossby waves inside out.”

 The geomagnetic field, which protects our planet from the harmful solar radiations, is generated by the rotation of magnetic iron in the Earth’s core. It is of immense importance for life on Earth because the charged particles emitted by the Sun would burn the atmosphere of Earth if not for this field. Bardsley found that all the measurements of magnetic declination, the difference between the True North and the point where the needle of a compass points, have shown a tendency to move westward. He examined all the experiments with respect to magnetic declination and came up with the same observation. He acknowledged that in his publications by saying,

“The westward drift manifests itself primarily as a series of blobs over the Atlantic near the equator.”

The estimated speed of drift given by him is 17 kilometers per year.

All the theories that have been proposed to explain this drift have focused on the outer core of the Earth. The most popular of them says that the outer core contains a gyre which is moving westwards and it drags the planet’s magnetic field with it. Bardsley questioned this theory by saying that there is no scientific evidence to support this claim so other possibilities could be true as well. According to his viewpoint, Rossby waves could be the reason for this westward drift. He agreed that it may seem odd as the crests of these waves move totally opposite to the drift, in the eastwards direction. As a counter to this, he explained that the energy of the environment is not always in the direction of the crests. He said,

“It is entirely possible to have a group of waves where the crests themselves are going east but the [bulk of the] energy is going westward.”

In light of this, he concluded that Rossby waves with a large-scale tendency to move energy westwards can cause this westward drift of the Earth.