Earth’s Magnetic Field Reversal 42,000 Years Ago Triggered a Global Environmental Crisis

Nearly 42,000 years ago, when Earth’s magnetic fields reversed, this triggered major environmental changes, extinction events, and long-term changes in human behavior, a new study reports.

The findings, made possible by a new radiocarbon record derived from New Zealand’s ancient kauri trees, raise important questions about the evolutionary impacts of geomagnetic reversals and excursions throughout the deeper geological record, the authors say.

“Before this work,” says author Chris Turney in a related video, “we knew there were a lot of things happening around the world at 42,000 years ago, but we didn’t know precisely how… For the first time, we’ve been able to precisely date what happened when Earth’s magnetic fields last flipped.”

Written in the geological record are numerous instances where the planet’s magnetic poles flipped. Today, such an event would almost certainly wreak havoc with modern electronic and satellite technologies. However, the potential environmental impacts of such events are virtually unknown.

The most recent major magnetic inversion, the Laschamps excursion, a relatively short-lived geomagnetic event that occurred ~41,000 years ago, provides one of the best opportunities to study the potential impacts of extreme changes to Earth’s magnetic field. However, despite compelling evidence from several paleoenvironmental records that suggest it coincided with significant environmental and ecological changes, the ability to precisely characterize this event and determine its role — if any — in contemporaneous global changes has been limited by an uncertain radiocarbon calibration for the period.

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