Nature can tell us a lot about the distant past something that no human being can reveal. Trees are a constituent part of this planet and their rings can show us many things about the climate in a particular year. For instance, an examination of the rings can reveal if there will be any hurricanes or forest fires according to the last winter whether it was wet or not, and so many other things.
The most amazing tree that was found on an excavation site was the ancient tree that contains a record of a reversal of Earth’s magnetic field. The tree, an Agathis australis, was dig out in Ngawha, on New Zealand’s North Island while the digging for the expansion of a geothermal power plant.The company, Ngāwhā Generation, a subsidiary of Northland power wholesaler Top Energy, gave the tree for examination so that scientists could take samples for study.
This tree is also known as kauri given by the Māori, and the one that was excavated was buried in 26 feet of soil having dimensions of eight feet in diameter and 65 feet in length. According to the carbon samples it lived for 1,500 years, between 41,000 and 42,500 years ago.
Alan Hogg, from New Zealand’s University of Waikato, stated the following:“There’s nothing like this anywhere in the world. This Ngāwhā kauri is unique.”
Being so ancient the kauri tree covers a point in the history of the Earth when the magnetic field almost reversed. At that particular time the magnetic north and south did not quite complete a full reversal. According o the findings of the scientists the Earth’s magnetic field is generated by the iron in the planet’s core. By moving around it produces electric currents that extend far into space. It is of vital importance as the magnetic field represents a barrier that protects the planet from the solar wind. The solar wind is a stream of charged particles coming from the Sun and the magnetic field protects the Earth from their influence. But, when the magnetic field reverses, it weakens so that the Earth is affected by more radiation coming from the Sun. Scientists believe that all the extinction events on Earth have been related to magnetic field reversals.
Thanks to the existence of this tree we can for the first time have a complete record of a near-reversal. The rings of this kauri tree will tell us all that as this is the first tree found that have survived this event.
“It’s the time it takes for this movement to occur that is the critical thing…We will map these changes much more accurately using the tree rings.”
The rings of the tree and the taken samples are being analyzed by Chris Turney from the University of New South Wales, who is an expert in paleoclimatology and climate change over the past 40,000 years. The Australia Research Council is in charge of this research and covers its funding.
This tree can give us an insight into what we should expect the next time it happens.
“We will have increased cosmic radiation. It will take out satellites and it might take out other communication infrastructure.”
His colleague, Turney added:
“The precious thing is this huge, lonely tree grew a remarkable period in our planet’s history when the Earth’s magnetic field flipped some 42,000 years ago, a period known as the Laschamp Excursion. Funded by the Australian Research Council we’re undertaking detailed measurements of the radioactive form of carbon through the tree rings.”
As per the knowledge of the scientists in that the past 83 million years on Earth, there have been 183 magnetic pole reversals. Each magnetic pole reversal lasts around 7,000 years till it fully completes. The scientific obtained data shows that the last full reversal happened around 780,000 years ago.
Monika Korte, the scientific director of the Niemegk Geomagnetic Observatory at GFZ Potsdam in Germany, states the following:
“It’s not a sudden flip, but a slow process, during which the field strength becomes weak, very probably the field becomes more complex and might show more than two poles for a while, and then builds up in strength and [aligns] in the opposite direction.”
NASA explains that the magnetic field reversals happen at random intervals and in the last 20 million years, it seems to have settled into a pattern, meaning happening once every 200,000 to 300,000 years.
However, there are some recent changes in the magnetic north pole that had moved unexpectedly. It moves steadily from the Canadian Arctic towards Siberia, but there has been some change in speed that the researchers had to update the World Magnetic Model (WMM), a representation of Earth’s magnetic field. The exact whereabouts of the northern and southern magnetic poles are of greatest essence and because of that the WMM is widely used in navigation by the U.S. Department of Defense, the U.K. Ministry of Defense and many civilian systems.
“Because the Earth’s magnetic field has a major effect on how much radiocarbon carbon is formed in the upper atmosphere, these precious analyses will allow us to investigate the magnitude and rate of change when the magnetic field reversed during the Laschamp; something not possible before and of great interest given recent changes in the Earth’s magnetic field. ”