January 17, 2009

Atlas Shrugs

Mars is a dead planet because it no longer has a liquid core. Doomed from the start because of its size and distance from the sun, Mars lost its protective magnetic field when its core cooled and solidified. Without that magnetic field to shield the planet’s surface from cosmic and solar radiation, the atmosphere and surface water were stripped away. No amount of manmade interference will ever make Mars the verdant planet of old science fiction. Without that magnetic field, it isn’t possible to keep a dense atmosphere or liquid water in amounts large enough to create an ecosphere that can support a complex food chain.

We have life on our planet in part because of our magnetic field. It shields us from searing cosmic radiation and solar radiation by deflecting it into space. Make no mistake, some of that radiation reaches us. We are feeling the effects now in terms of global warming.

Think of the magnetic field as two halves of a hollow globe wrapped around the earth. The polarity we call “north” pulls inward to the center of the earth; “south” pushes out from the center. Created by the effect of a spinning liquid iron core around a solid center, the field is constantly in flux due to the currents of the core and the wobble of the earth’s spin. The “north” half rests on our northern hemisphere and the “south” half wraps around our southern hemisphere. This isn’t as obvious as it sounds, because it wasn’t always so. Every 600,000 years or so, the magnetic poles flip.

Let’s see if I can describe the progression so that you can picture it. Make a “spider on the mirror” with your hands, open and touching on all five fingers, one hand over the other. Now gently pulse your fingers. That is a healthy and strong magnetic field, deflecting the radiation except at the earth’s north pole, where it strips away any possible chance for plant life. As the millennia march on, the flux in the field becomes pronounced, and waves start to form where the polarities intersect. (Make your fingers pulse so that they start to slip between each other.) Eventually, the field is so unstable that portions of each pole begin to show up in the other hemisphere. (Pulse your fingers in big movements so that your fingers meet at the knuckles on the downbeat. See how “north” invades “south” and vice versa?)

This blurring of the poles—mixing north in south and south in north—weakens the magnetic field. It is no longer a strong current leading to one pole. Consequently, more radiation reaches the earth’s surface. Combined with the 33/66/99 year cycles of solar activity, we have periods of extreme drought and global warming until the magnetic field is so unstable that it completely flips and stabilizes—until the next time, about 600,000 years later. And all hell will break loose for living organisms when it does, but only for a blink of an eye in geologic terms. Atlas shrugs.

Our planet is about 200,000 years overdue for reversing the magnetic field. We know this because of lava and manmade pottery. When matter is in a liquid state, its atoms line up with the magnetic field. As the matter solidifies, the atoms are locked into place, frozen for all time pointing to magnetic north. Examination of layers of lava and manmade pottery has allowed us to map out ancient magnetic patterns. Some highly active “hot spots” such as the Hawaiian Islands yield rich data, some of which show changes in polarity literally overnight and back again. We have mapped large areas today which are “polar opposites” to the field that surrounds them. Unusual migratory behavior coincides with these spots.

Earth's magnetic field in 2002. Blue indicates inward pull; 
yellow is outward.
Graphic courtesy of NASA.

The fluctuations of the magnetic field play a huge role in global warming. Why aren’t we hearing more about this? I suspect that political correctness prevents scientists from putting forth this theory too strongly because funding comes from sources attuned to public opinion. Make no mistake, we have to clean up our act environmentally—quickly and with purpose—but mankind alone is not responsible for climatic change on a global scale. That ideology, which make a god of the earth and men its eternal enemy, smacks of the hubris that put us at the center of the universe so long ago.


Patrick said...

The studies I've read do make mention of this element, but I think human influence gets more attention for a few reasons. One is the fact that the world scientific community is unified in the belief that human beings are driving this climate change more than any other change in history. Another reason for focusing on the human factor, at least in the US, might be that we are playing catch-up with the discussion. For too long a false sense of controversy was generated by powerful people for their own cynical purposes. A tone of panic may be ringing out a bit right now, might even be useful for the time being to combat complacency, but I think it will disappate. Another reason the human element may be getting more attention is the fact that it's something we can control, at least in theory. Like giant asteroids hitting the earth, the magnetic field switch is something that has happened before, will again, but our only response options are to live through it if possible, and clean up afterwards. Greenhouse gases are, as you point out, something we can and should do something about. Much is beyond our control, but when we can, I believe we should be responsible stewards of the earth.

Roxrocks said...

This was very informative!

I agree with Patrick. We still have a responsibility to our planet.

Have you seen Wall-E yet? Made me cry for us.

Greg said...

I've hesitated seeing Wall-E for just that reason, I think, Rox. Soon, tho.

I'd heard of this before, even in our recently non-science friendly political climate, but then I think I am often counted amongst that choir folks are often preaching to.

Still, we need to focus on what we can do, and simply have hope that the rest will fall into place.

somewherejoe said...

You're scaring me!