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Earth’s Magnetic Pole Reversals Can Take 70,000 Years

February 5, 2026

Earth’s magnetic field, which protects our planet from harmful solar radiation, is not as stable as many people assume. Throughout history, the magnetic north and south poles have repeatedly switched places in events known as geomagnetic reversals. A groundbreaking new study has revealed that some of these reversals took far longer than scientists previously believed.

How the Magnetic Field Works

The Earth’s magnetic field is generated by movements in the liquid nickel-iron outer core, which lies about 2,900 kilometers beneath our feet. This swirling molten metal creates electrical currents that produce the magnetic field surrounding our planet. The field acts as a protective shield, deflecting dangerous particles and radiation from the sun and outer space.

Over the past 170 million years, the magnetic poles have reversed approximately 540 times. Until now, scientists believed that each reversal typically took around 10,000 years to complete. However, new research challenges this understanding.

The Discovery

An international team of scientists from the University of Utah, France, and Japan made this discovery by analyzing sediment cores extracted from the North Atlantic Ocean floor. During a two-month expedition in 2012, the researchers drilled up to 300 meters below the seabed near Newfoundland, Canada.

The sediments they collected contained tiny crystals of magnetite, a magnetic mineral. These crystals act like tiny compasses, recording the direction of Earth’s magnetic field at the time the sediments were deposited. By examining these “time capsules,” the scientists could reconstruct the history of geomagnetic reversals.

Unexpected Findings

One 8-meter-thick layer of sediment caught the researchers’ attention. It appeared to record an unusually long reversal period from around 40 million years ago, during the Eocene Epoch. After careful analysis, the team discovered that one reversal had lasted 18,000 years, while another had taken an astonishing 70,000 years to complete.

“This finding unveiled an extraordinarily prolonged reversal process, challenging conventional understanding and leaving us genuinely astonished,” wrote lead author Yuhji Yamamoto from Japan’s Kochi University.

Implications for Life on Earth

These extended reversals have significant implications. During a reversal, the magnetic field weakens considerably, allowing more cosmic radiation to reach Earth’s surface. Professor Peter Lippert from the University of Utah explained that this increased radiation could affect organisms’ ability to navigate, potentially increase genetic mutation rates, and even cause atmospheric erosion.

The findings were published in the journal Communications Earth & Environment, offering scientists new insights into one of Earth’s most fundamental and mysterious processes.

Vocabulary Help

• reversal — the process of changing to the opposite state or direction
• sediment — material (like mud or sand) that settles at the bottom of water
• core (noun) — the central or innermost part of something
• deflect — to make something change direction
• implications — possible future effects or results

Grammar Focus

• Present perfect for recent discoveries: “A new study has revealed…” / “Scientists have discovered…”
• Passive voice for scientific processes: “The field is generated by…” / “The sediments were collected…”
• Relative clauses: “…the magnetic field, which protects our planet…”

Source: Phys.org