Earth's magnetic field flipped 40,000 years ago. Here's how it sounded

During the Laschamps event, Earth's magnetic field weakened to a mere 5 per cent of its current strength.

In Short

• This dramatic decrease allowed an influx of cosmic rays
• The weakened magnetic field had far-reaching effects
• It contributed to global climate change

Scientists have uncovered new insights into what happened when Earth's magnetic field dramatically flipped, shedding light on the potential consequences of such events.

The most recent major reversal, known as the Laschamps event, occurred approximately 40,000 years ago and left a lasting impact on our planet's environment and possibly even human behaviour.

During the Laschamps event, Earth's magnetic field weakened to a mere 5 per cent of its current strength.

HEAR THE SOUND OF EARTH'S MAGNETIC FIELD FLIPPING

This dramatic decrease allowed an influx of cosmic rays to penetrate our atmosphere, leaving telltale isotopic signatures in ice and marine sediments.

Researchers found that levels of beryllium-10, an isotope formed when cosmic rays interact with the atmosphere, doubled during this period.

The weakened magnetic field had far-reaching effects, potentially contributing to climate change, the extinction of Australia's megafauna, and alterations in human cave use.

The reversal process took about 250 years to complete and persisted for roughly 440 years before returning to its normal orientation.

While recent magnetic field anomalies, such as the weakening over the Atlantic Ocean, have raised concerns about an impending reversal, current research suggests these fluctuations may not necessarily indicate an imminent flip.

However, the South Atlantic anomaly is exposing satellites in the area to higher levels of radiation, highlighting the ongoing importance of monitoring our planet's magnetic field.

To better understand and predict geomagnetic fluctuations, the European Space Agency's Swarm constellation has been measuring magnetic signals from various Earth systems since 2013.

This ongoing research is crucial for assessing potential environmental impacts and preparing for future extreme events that could affect our planet's magnetic shield.