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Old tree with record of Earth's magnetic field reversal discovered in its rings



In New Zealand, an old tree has been discovered in which a reversal of the Earth's magnetic field is recorded. The tree – an Agathis australis, better known as the Māori name kauri – was found in Ngawha on New Zealand's North Island during excavation work to build a geothermal power plant, stuff.nz reports.

The tree, which was buried in 26 feet of earth, measures eight feet in diameter and 65 feet in length. Carbon dating showed that it lived between 41,000 and 42,500 years ago 1,500 years ago.

"There's nothing like it anywhere in the world," said Alan Hogg of the New Zealand University of Waikato opposite the website. "This ngāwhā kauri is unique."

The life of the Kauri Tree covers one point in Earth's history when the magnetic field nearly reversed. At that time, the magnetic north and south have made an excursion, but have not completed a complete reversal.

It is believed that the earth's magnetic field is generated by the iron in the nucleus of the planet. During the movement, electric currents are generated which extend far into space. The magnetic field acts as a barrier and protects the earth from the solar wind. This is a stream of charged particles from the sun that could peel off the ozone layer if it were to affect the atmosphere.

When the magnetic field reverses or attempts to do so, it weakens, causing more radiation to be released from the sun. So far, scientists have associated extinction events with magnetic field reversals.

The newly discovered kauri tree rings contain a complete record of a near-reversal ̵

1; for the first time a tree was found that lived throughout the event. "It's the time it takes for this movement to happen, and that's the key … we'll be more accurate in mapping those changes using the tree rings," Hogg stuff.nz said.

Samples of the tree are now being analyzed by scientists led by Chris Turney of the University of New South Wales – an expert in paleoclimatology and climate change. If you understand what happened to the tree during the event, you can get a glimpse of what we should expect next time. "We will increase the cosmic radiation and it will shut down satellites and other communication infrastructures," said Hogg.

Magnetic field reversals occur at random intervals, although they seem to have crept in during the last 20 million years. A pattern that occurs every 200,000 to 300,000 years, NASA says. The last complete reversal took place about 780,000 years ago.

Scientists recently announced that the magnetic North Pole had moved unexpectedly. Instead of constantly moving from the Canadian Arctic to Siberia, researchers had to update the World Magnetic Model (WMM), a representation of the Earth's magnetic field used by GPS systems worldwide.

  Northern Lights
Photo. Aurora are generated by the solar wind, which interacts with the Earth's magnetic field.
iStock


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