Pole Shift: Why Does the North Pole Move?

Earth's magnetic North Pole moves in loops of up to 50 miles (80 km) per day. But its actual location, an average of all these loops, is also moving at forward speed of around 45 kilometers (28 miles) a year [Source: NOAA].

From 1831 to 2021, the pole wandered a total of about 683 miles (1,100 kilometers) [source: NASA]. The magnetic South Pole moves in a similar fashion. Every once in a while, the two poles completely flip locations.

Every several hundred thousand years, the north and south poles swap locations. Scientists can study when in Earth's geologic history this has happened by examining deep ocean sediment samples.

Rocks on the ocean floor retain traces of the field, similar to a recording on a magnetic tape. The last time the poles switched was 780,000 years ago, and it's happened about 400 times in 330 million years.

Each reversal takes a thousand years or so to complete, and it takes longer for the shift to take effect at the equator than at the poles.

The field has weakened about 10% in the last 150 years. Some people think this is a sign of a flip in progress, but there is limited scientific evidence to support this hypothesis. According to NASA, the Earth's electromagnetic field is "about as strong as it’s been in the past 100,000 years."

If a magnetic reversal were to occur, it's unlikely it would impact the Earth's climate. According to NASA, "there is no known physical mechanism capable of connecting weather conditions at Earth’s surface with electromagnetic currents in space." Additionally, fossil records from the last major pole reversal show that the Earth remained stable despite a weakened magnetic field.

The Earth's physical structure is behind all this magnetic shifting. The planet's inner core is made of solid iron. Surrounding the inner core is a molten outer core of liquid iron. The next layer out, the mantle, is solid but malleable, like plastic. Finally, the layer we see every day is called the crust.

The Earth itself spins on its axis. The inner core spins as well, and it spins at a different rate than the outer core. This creates a dynamo effect, or convections and currents within the core. This is what creates the Earth's magnetic field — it's like a giant electromagnet.

Exactly how the dynamo effect changes the field isn't widely understood. Shifts in the core's rate of spin and the currents within the molten material most likely affect the planet's field and the location of the poles. In other words, the poles move because the convection in the core changes.

These changes might also cause polarity reversals. Irregularities where the core and mantle meet and changes to the Earth's crust, like large earthquakes, can also change the magnetic field.

The magnetic North Pole is responsible for more than just the direction a compass points. It's also the source of the aurora borealis, the dramatic lights that appear when solar radiation bounces off the Earth's magnetic field.

This happens at the South Pole as well. In the southern hemisphere, the lights are called the aurora australis.