Radiation mayhem if Earth's poles flip
By Jonathan Leake (january 2003, London) |
The North Pole is on the move. Scientists have found
large holes appearing in the Earth's
magnetic field, suggesting the north and south poles
are preparing to reverse positions in a magnetic flip.
A period of chaos could be imminent when compasses no
longer point north, migrating animals head in the wrong
direction and satellites are burnt up by solar radiation.
The holes lie over the south Atlantic and the Arctic.
The changes were revealed after detailed data from the
Danish Orsted satellite was analysed. Results were compared
with data from earlier satellites.
The speed of the change has surprised scientists. Nils
Olsen, of the Centre for Planetary
Science in Denmark, one of several centres analysing
the data, said the Earth's
core appeared to be undergoing dramatic changes. He
added: "This could be the state in which the Earth's
geodynamo operates before reversing."
The geodynamo is the way the magnetic field is generated:
by currents of molten iron flowing around a solid core.
Sometimes giant vortices form in the liquid metal and
they can change or even reverse the magnetic fields
above them. Olsen's team believes
vortices have formed beneath the North Pole and south
Atlantic. If they become powerful enough they could
reverse all the other currents, causing the north and
south poles to switch places.
Andy Jackson, a specialist
in geomagnetism at Leeds University, said a change was
long overdue: "Such flips normally happen every
500,000 years, but it has been 750,000 years since the
last one."
The change could affect humans and wildlife.
The magnetosphere gives vital protection against searing
solar radiation that would otherwise sterilise Earth.
Although the magnetic field would probably not disappear
altogether, it may weaken while the poles switch. The
resulting surge in radiation could cause cancers, reduce
crops and confuse migrating animals, including whales
and pigeons.
From the Sunday Times
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Will compasses point south?
(Tuesday, 20. July 2004, 19:11) |
The collapse of the Earth’s
magnetic field, which both guards the planet and guides
many of its creatures, appears to have started in earnest
about 150 years ago. The field’s strength has
waned 10 percent to 15 percent, and the deterioration
has accelerated of late, increasing debate over whether
it portends a reversal of the lines of magnetic force
that normally envelop the Earth.
...Last month, the European Space
Agency approved the world’s largest effort
at tracking the field’s shifts. A trio of new
satellites, called Swarm, are to monitor the
collapsing field with far greater precision than before
and help scientists forecast its prospective state.
“We want to get some idea of how this would evolve
in the near future, just like people trying to predict
the weather,” said Dr. Gauthier
Hulot, a French geophysicist working on the satellite
plan.
“I’m personally quite convinced we should
be able to work out the first predictions by the end
of the mission.”
From the NY Times
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Patrick Geryl © 2005 ~ 2007 / site by kAOz :: happyland |
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