Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: Vanessa Penman on 20/01/2011 00:30:03
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Vanessa Penman asked the Naked Scientists:
Hello Chris,
Thank you for your very interesting show on Radio 702.
I would be so grateful if you could please share with me your views on the rumors that the Earth's poles are going to / in the process of reversing.
Is this possible? How does this happen and if it should, what would we experience here on Earth?
Following onto this - why are there so many earthquakes and other natural disasters happening at this time - or did these things always happen it is just now that we are so connected via the internet that we have become aware of them? Is there in validity in the 2012 (something big is going to happen) story?
Thank you again and looking forward to your reply.
All the best for this year,
Kindest Regards,
Vanessa.
What do you think?
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several posts have addressed magnetic pole reversal in the past:
http://www.thenakedscientists.com/forum/index.php?topic=28908.0
http://www.thenakedscientists.com/forum/index.php?topic=17746.0
http://www.thenakedscientists.com/forum/index.php?topic=30717.0
Are there more earthquakes now? Not according to the USGS- nor are there more large earthquakes. I think you are right that we are more connected so hear more these days.
2012? Your guess is as good as anyones. As the old saying goes "The world can't end today, it's already tomorrow in Australia."
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One thing that is happening in earth sciences, climatology, meteorology, and etc... is that we are now getting far more and far better instruments.
And, with these instruments, we're seeing a multitude of "odd" things. Unfortunately we don't know what is truly normal. So, we see the ocean temperatures rising by a fraction of a degree and it becomes a global emergency... and thus a major effort is made to determine historical temperatures, and deploy newer and better scientific instruments (noting, of course, that any instrumentation changes can introduce new types of error).
The magnetic field apparently makes major shifts a few times every million years as evidenced by natural magnetite getting buried in sedimentary rock, or incorporated in fixed igneous rock.
Everything that I've heard in the past was that the magnetic field was a result of the spinning earth from which I would have concluded that the magnetic field would be difficult to change.
Apparently it does change regularly.
Wikipedia has a couple of articles (from which the images are taken).
http://en.wikipedia.org/wiki/Earth%27s_magnetic_field
http://en.wikipedia.org/wiki/Geomagnetic_reversal
Somewhat finer resolution in the Holocene here:
http://igpphome.ucsd.edu/~cathy/Publications/Holocene/korte_constable_cals7k_dipole_epsl_2005.pdf
If you look at the polar reversals over the last few million years, our planet has spent about half the time with the N/S poles reversed. First chart, 5 million year timeframe, second chart is the most recent 1 million years.
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2F1%2F13%2FGeomagnetic_polarity_late_Cenozoic.svg%2F198px-Geomagnetic_polarity_late_Cenozoic.svg.png&hash=2084cd21f1de297cd7b4c9d1cd22ef0a) (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2F9%2F9f%2FBrunhes_geomagnetism_western_US.png%2F482px-Brunhes_geomagnetism_western_US.png&hash=87619e88f6e973284a9788b1b0b3cfe5)
However,
There seems to be a random variation of field strength, as well as an oscillation of the location of "Magnetic North", although I'm having some troubles tracking the actual current state.
However, nothing seems to indicate that we are currently outside of the "normal" variation cycles.
¾ million years is a long time without a major shift polar shift.
It is believed that many species use magnetic fields as part of their normal navigation/migration including salmon, bees, and many migratory birds. If the magnetic shifts were frequent, they would have a natural mechanism to cope with it. However, it is likely that they have evolved somewhat in the last ¾ million years, and theoretically could have lost some of the magnetic shift coping mechanisms.
What causes the reversals?
I think it is still up for debate, but the Sun has a very dynamic magnetic field with frequent field reversals (at least now). Perhaps there is a coercion effect from the sun.
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I think it is still up for debate
My money is on a similar mechanism as for the Milankovitch cycles (http://en.wikipedia.org/wiki/Milankovic_cycles):
Earth's axis oscillating (http://en.wikipedia.org/wiki/Milankovic_cycles#Axial_precession) causing changes in the motion of the metal cores (http://en.wikipedia.org/wiki/Earth_core) which generate the magnetic field.