An ancient Agathis australis tree with rings that document the near-reversal of Earth’s magnetic field has been discovered on New Zealand’s north island. The tree, which measures 8 feet in diameter and 65 feet in length, was found buried under 26 feet of soil. Carbon dating shows that the tree was alive for 1,500 years and lived between 41,000 and 42,500 years ago.
The tree’s rings show a complete record of the near-reversal of Earth’s magnetic field. This is the first time that a tree documenting the full event has ever been found. Reversals in our planet’s magnetic field have been linked to extinction events. Scientists studying the tree say that it provides insight into what we might expect the next time we experience a reversal of Earth’s magnetic field.
The radioactive carbon in the tree’s rings provides a complete record of the near-reversal of the Earth’s magnetic fields that occurred during the tree’s lifetime.
NASA warned earlier this year that the magnetic “north pole” is speeding toward Russia at 30 miles per year, indicating the start of a total pole reversal.
“Earth’s magnetic field is thought to be generated by the iron in the planet’s core,” Newsweek reports. “As it moves around, it produces electric currents that extend far into space. The magnetic field acts as a barrier, protecting Earth from the solar wind.”
“When the magnetic field reverses—or attempts to—it gets weaker, leading to more radiation from the Sun getting through.”
“There’s nothing like this anywhere in the world,” Alan Hogg, from the New Zealand’s University of Waikato, told Stuff Magazine. “We will map these changes much more accurately using the tree rings.”
While it can take thousands of years for the poles to completely flip, their journey to the other side can cause chaos in the meantime, as the magnetic field lines cross and become jumbled, weakening their ability to protect us from solar radiation.
And they’ve been on the move for the past 3000 years.
Scientists are scrambling to develop models to determine how that will look in practice. This tree will assist them in doing so.
“As Earth’s magnetic shield fails, so do its satellites,” writes Jonathan O’Callaghan, a space journalist for Phys.org.
“First, our communications satellites in the highest orbits go down. Next, astronauts in low-Earth orbit can no longer phone home. And finally, cosmic rays start to bombard every human on Earth. This is a possibility that we may start to face not in the next million years, not in the next thousand, but in the next hundred.”