Scientists recently discovered that Earth’s inner core reversed the direction in which it spins. Now, they’re discovering Earth’s inner core is changing shape, twisting and deforming in ways researchers could never have imagined.
The Earth’s inner core is a solid sphere composed mostly of iron and nickel. A 2024 study took a look at seismic waves generated by earthquakes. Since 2010, the Earth’s inner core slowed and eventually reversed its spin relative to its outer layers. The latest study, undertaken by Will Kwong from the USC, in February 2025, published in Nature Geoscience, showed the inner core is undergoing structural transformation.
The liquid outer core might be pushing against the inner core, leading to topographical changes to the inner core that closely resemble landslides we on the surface of the earth. All of this means that there are forces deep within the earth that are changing the physical nature of the inner core, which in turn influences the planet’s magnetosphere, which protects the earth from solar radiation.
Why any of this is happening is anyone’s guess. It’s going take a lot more time, money and research to figure it out. One thing the researchers are comfortable enough to speculate on is that these deformations of the inner core might be more widespread than data currently suggests.
Studies of Earth’s magnetic field have revealed much of its history
We know that over the past 200 years, the magnetic field has weakened about 9% on a global average. However, paleo magnetic studies show the field is actually about the strongest it’s been in the past 100,000 years and is twice as intense as its million-year average.
Magnetic stripes around mid-ocean ridges reveal the history of Earth’s magnetic field for millions of years. The study of Earth’s past magnetism is called paleomagnetism.
There’s a well-known “weak spot” in the magnetosphere, present year-round. Located over South America and the southern Atlantic Ocean, the South Atlantic Anomaly (SAA) is an area where the solar wind penetrates closer to Earth’s surface. It’s created by the combined influences of the geodynamo and the tilt of Earth’s magnetic axis. While charged solar particles and cosmic ray particles within the SAA can fry spacecraft electronics, they don’t affect life on Earth’s surface.
The positions of Earth’s magnetic poles are continually moving. Since it was first precisely located by British Royal Navy officer and polar explorer, Sir James Clark Ross, in 1831, the magnetic north pole’s position has gradually drifted north-northwest by more than 1,100 kilometres and its forward speed has increased, from about 16 kilometres per year to about 55 kilometres per year.
Earth’s magnetic field acts like a protective shield around the planet, repelling and trapping charged particles from the Sun. Over South America and the southern Atlantic Ocean, an unusually weak spot in the field – called the South Atlantic Anomaly (SAA) – allows these particles to dip closer to the surface than normal. Currently, the SAA creates no visible impacts on daily life on the surface. However, recent observations and forecasts show that the region is expanding westward and continuing to weaken in intensity.
Earth’s magnetic poles are not the same as its geodetic poles, which most people are more familiar with. The locations of Earth’s geodetic poles are determined by the rotational axis our planet spins upon. The axis doesn’t spin evenly, it wobbles slightly. This causes the position of the true North Pole to shift slightly over time. Numerous processes on Earth’s surface and within its interior contribute to this wander, but it’s primarily due to the movement of water around Earth.
Since observations began, the position of Earth’s rotational axis has drifted toward North America by about 37 feet (12 metres), though never more than about 7 inches (17 centimetres) in a year. These wobbles don’t affect our daily life, but must be considered to get accurate results from global navigation satellite systems, satellites and ground observatories.
Pole Reversals
By far the most dramatic changes impacting Earth’s magnetosphere are pole reversals. During a pole reversal, Earth’s magnetic north and south poles swap locations. While that may sound like a big deal, pole reversals are actually common in Earth’s geologic history. Paleo magnetic records show Earth’s magnetic poles have reversed 183 times in the last 83 million years and at least several hundred times in the past 160 million years. The time intervals between reversals have fluctuated widely, but average about 300,000 years, with the last taking place about 780,000 years ago. Scientists don’t know what drives pole reversal frequency, but it may be due to convection processes in Earth’s mantle.
