From: Paul Doherty (pauld@exploratorium.edu)
Date: Tue Jul 13 2004 - 17:22:30 PDT
Message-Id: <l03110726bd1a2caaa949@[192.168.112.30]> Date: Tue, 13 Jul 2004 17:22:30 -0700 From: Paul Doherty <pauld@exploratorium.edu> Subject: Re: pinhole Pinhole: Is this true: Earth's magnetic field is collapsing, scientists say
Hi Sue
Measurments show that the magnetic field strength at the surface of the
earth has been decreasing for over 100 years and the rate of decrease has
been increasing.
This is consistent with mathematical models of what happens to the field
before a magnetic field flip .
However the actual flip is still a couple of thousand years away so it's
not time to panic yet. And in addition sometimes the field weakens and then
strengthens again befor e going to small enough values to allow a flip of
the field.
Paul D
>Paul,
>
>I just received this from a friend in Stockton. Paul, how accurate is this
>information? Trying to check its accuracy through regular internet checks
>is not
>proving helpful. Any "light" you can put on the subject is appreciated.
>
>Thanks,
>Sue
>
>SEATTLE POST-INTELLIGENCER
>
>http://seattlepi.nwsource.com/national/181843_magnetism13.html
>
>
>Earth's magnetic field is collapsing, scientists say
>
>Change will wreak havoc -- but not for about 2,000 years
>
>
>Tuesday, July 13, 2004
>
>
>By WILLIAM J. BROAD
>
>THE NEW YORK TIMES
>
>
>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 so far and
>this deterioration has accelerated lately, increasing debate over whether it
>portends a reversal of the lines of magnetic force that normally envelop
>the Earth.
>
>
>During a reversal, the main field weakens, almost vanishes, and then
>reappears with opposite polarity. Afterward, compass needles that normally
>point north
>would point south, and during the thousands of years of transition, much in
>the heavens and Earth would go askew.
>
>
>A reversal could knock out power grids, hurt astronauts and satellites, widen
>atmospheric ozone holes, send polar auroras flashing to the equator and
>confuse birds, fish and migratory animals that rely on the steadiness of the
>magnetic field as a navigation aid. But experts said the repercussions
>would fall
>short of catastrophic, despite a few proclamations of doom and sketchy
>evidence
>of past links between field reversals and species extinctions.
>
>
>Although a total flip may be hundreds or thousands of years away, the rapid
>decline in magnetic strength is already damaging satellites.
>
>
>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, is 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 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."
>
>
>The discipline is one of a number -- such as high-energy physics and aspects
>of space science -- in which Europeans recently have come from behind to
>seize
>the initiative, dismaying some American experts.
>
>
>No matter what the new findings, the public has no reason to panic,
>scientists say. Even if a flip is imminent, it might take 2,000 years to
>mature. The
>last one took place 780,000 years ago, when Homo erectus was still
>learning how
>to make stone tools.
>
>
>Some experts suggest a reversal is overdue. "The fact that it's dropping so
>rapidly gives you pause," said John Tarduno, a professor of geophysics at the
>University of Rochester. "It looks like things we see in computer models
>of a re
>versal."
>
>
>Deep inside the Earth, the magnetic field arises as the fluid core oozes with
>hot currents of molten iron, and this mechanical energy gets converted into
>electromagnetism. It is known as the geodynamo. In a car's generator, the
>same
>principle turns mechanical energy into electricity.
>
>
>No one knows precisely why the field periodically reverses, but scientists
>say the responsibility probably lies with changes in the turbulent flows of
>molten iron, which they envision as similar to the churning gases that
>make up the
>clouds of Jupiter.
>
>
>© 1998-2004 Seattle Post-Intelligencer
>
>
>http://seattlepi.nwsource.com/printer2/index.asp?ploc=b&refer=http://seattlepi
>.nwsource.com/national/181843_magnetism13.html
>
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