- Southern Africa is experiencing weird vibes, according
to scientists studying one of the more profound upheavals awaiting planet
Earth.
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- This forthcoming revolution is a reversal in the Earth's
magnetic field, an event that occurs every 500 000 years or so.
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- Signs that the reversal is about to happen again are
nowhere more apparent than over Southern Africa, according to Dr Pieter
Kotze, head of the geomagnetism group at the Hermanus Magnetic Observatory
in the southern Cape.
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- Satellites in low-Earth orbit over Southern Africa are
already showing signs of radiation damage suffered as a result of the Earth's
magnetic field weakening above our part of the planet. The field forms
the magneto sphere, which, like the Earth's ozone layer, protects the planet
from the sun's harmful radiation.
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- Other symptoms destined to become apparent in the years
ahead include the aurora australis, or southern lights. Usually seen only
over the South Pole, these will become visible closer to the equator as
the Earth's magnetic field weakens and disappears. Eventually, on past
form, the field will reappear but with magnetic north and south pole changing
places, as they have done for billions of years.
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- According to an article in the New York Times this week,
the change will be devastating for migratory animals such as loggerhead
turtles, which use the Earth's magnetic field to migrate 8 000km around
the Atlantic. Bees, swallows, cranes, salmon, homing pigeons, frogs and
eagles may also lose their way between breeding and feeding grounds.
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- Humans will suffer, too. The (temporary) disappearance
of the magnetic field ahead of its reversal will lead to increased occurrences
of radiation-induced cancer, Kotze said.
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- Commenting on the New York Times report, Kotze said that
the decay in the Earth's magnetic field was becoming increasingly apparent
in "the South Atlantic anomaly", a huge deviation in the Earth's
magnetic field discovered with the help of the Hermanus Magnetic Observatory.
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- This month, the European Space Agency (ESA) approved
a multimillion-euro space mission, called Swarm, to measure the anomaly,
which stretches from Southern Africa towards South America.
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- The ESA's scientists believe that this anomaly, as revealed
by the occasional "geomagnetic jerk" to which our part of the
world is prone, will provide a clue to predicting the next "flip"
in the Earth's magnetic field, now 250 000 years overdue - as these things
go. Three ESA satellites, flying in low-Earth orbit (400km to 500km up)
after their launch in 2009, will measure the variation over Southern Africa.
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- The observatory has also recorded a faster-growing deviation
between true north and magnetic north over Southern Africa during the past
10 years, drifting steadily westward. Taken together, the blip and this
drift point to an imminent reversal in the Earth's north-south magnetic
alignment.
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- "W e should be able to work out the first predictions
by the end of the [Swarm] mission," Gauthier Hulot, an ESA geophysicist
and a colleague of Kotze's, told the New York Times.
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- The discovery of the "anomalous field behaviour
over Southern Africa" drew wide attention, reported the US newspaper,
because "it seemed consistent with what the [ESA's] computer simulations
identified as the possible beginnings of a flip".
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- Kotze said that, "these are all indications that
we have conditions similar to the last reversal, 780 000 years ago. So
it means that we are due for another one soon." In geological terms,
however, "soon" could mean anytime between tomorrow and the next
3 000 years.
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- Kotze said the anomaly was the result of "things
happening" far below the Earth's surface.
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- At the boundary between the mantle and the outer core
(more than 3 000km below Southern Africa) disruptions were occurring in
the flow of the Earth's liquid outer core (mostly iron), he explained.
This created "a reverse dynamo situation", which is becoming
increasingly apparent as variations in the magnetic field above the Earth's
surface.
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- http://www.sundaytimes.co.za/2004/07/18/news/news14.asp
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