PDA

View Full Version : Reversal of magnetic poles upon migration


Loren Booda
Jan11-07, 01:00 AM
Will a sudden change in the orientation of earth's magnetic poles have catastrophic consequences for migrating species?

DaveC426913
Jan11-07, 10:35 AM
1] They don't tend to be sudden.

2] Migrating species seem to have survived the reversals that have been happening every eon since the dawn of time.

http://upload.wikimedia.org/wikipedia/en/7/7e/Geomagnetic_late_cenozoic-220x768px.png

Loren Booda
Jan11-07, 06:01 PM
DaveC426913,

You make two good points, but I do not understand the link you provided.

Animals in general have survived, but do migrating species particularly suffer? Are times required for species adaptation to magnetic pole reversals comparable (<,=,>) to the reversals themselves?

Evo
Jan11-07, 07:35 PM
Scientists don't believe there will be any major problems. They talk about effects here.

Would a dramatic change in the Earth's magnetic field affect creatures that rely on it during migration?

http://www.pbs.org/wgbh/nova/magnetic/animals.html

Loren Booda
Jan11-07, 11:47 PM
Interesting arguments toward the end of the article. For now, I'm sold. Here is the pertinent exerpt from the article Evo provided:Indeed, the researchers I spoke with all thought that organisms would be able to adjust to an acute weakening or even complete reversal of the magnetic field. "My gut reaction is it's not going to have an impact," says Frank Paladino, the Indiana-Purdue University leatherback researcher whose project I was visiting that night in 1993.

History seems to back this up. There is no firm evidence that the many magnetic field reversals that have taken place throughout our planet's history (see When Compasses Point South) have coincided with or triggered extinctions. Reversals take hundreds if not thousands of years to complete, and because for any one type of animal that represents hundreds or thousands of generations, species have time to accommodate to the change. Moreover, Kirschvink notes that even if the main dipole field were to collapse—an event that can last for up to 10,000 years during a reversal—residual fields 5 or 10 percent as strong as the main field would remain on the surface, and animals would be able to use those quite well for migration.Let's hope.

DaveC426913
Jan12-07, 12:32 AM
DaveC426913,

You make two good points, but I do not understand the link you provided.

Sorry, I posted it out of context.

http://en.wikipedia.org/wiki/Geomagnetic_reversal