Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 15/09/2016 12:23:02
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Karl Vieweg asked the Naked Scientists:
Hi Chris,
In a recent episode you talked about the earth's magnetic field and how it has collapsed/changed several times in the past, and how such a collapse would harm humans and their technology.
Now I wonder: Assume we knew that 10 year from now the magnetic field would collapse again. Would mankind be able to artificially substitute earth's magnetic field? Could we stack up enough permanent magnets? Or coil up some wire around the globe, running a current through it to re-create the magnetic field?
Looking forward to your thoughts and answers in your podcast episodes (http://www.thenakedscientists.com/HTML/podcasts/), best regards,
Karl Vieweg
What do you think?
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Best estimates suggest that the geodynamo is running at about 10^12 watts so in principle we could generate enough electricity to substitute for it. Indeed this could be the stuff of a neat sci-fi plot: staving off the collapse of the magnetosphere by a huge international collaboration, or terraforming a small planet (moon, mars, big asteroid?) with a ring of nuclear power stations to protect the inhabitants from cosmic radiation.
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Currently, the Earth's magnetic field is primarily a Dipole, with a North+South pole.
It is thought that although the dipole field may weaken and reverse, it is possible that there could be a weak Quadrupole field remaining during the transition, with two (or more) North poles and a similar number of South poles. We might need new names for them, like South American pole, and smartphones would need to download a lot more information about the direction of the magnetic field in your current location - updated regularly (perhaps weekly).
The atmosphere would still act as a pretty good protection against cosmic rays reaching the ground, and would not blow away in the thousand years or so it would take to make the transition. If you were worried, you could build a house underground - a meter or so of soil provides pretty good protection from any residual cosmic rays.
See the diagram "During a reversal" & "Effects on Biosphere" at:
https://en.wikipedia.org/wiki/Geomagnetic_reversal#Causes
The weakest part of the Earth's magnetic field is currently over Paraguay in South America:
https://upload.wikimedia.org/wikipedia/commons/thumb/f/f6/World_Magnetic_Field_2015.pdf/page1-1280px-World_Magnetic_Field_2015.pdf.jpg