Hi Diziet Sma!
Hm, some of what you said is simply not correct the way you put it.
For reasons unknown, Earths magnetic field has been weakening for the last 2000 years. Some 500 years ago, the rate of decrease became much more rapid. Another acceleration took place about 100 years ago, to the point that in the last century alone there has been a 50% decrease in field strength. In the last 20 years or so, it has also become erratic, to the point that aeronautical maps of the world have had to be revised globally in order for the autopilot systems to work.
This is basically correct, but the reasons are not unknown. The earth's iron core has some pretty massive electrical charges rotating inside. That produces a magnetic field. This is what makes a compass move. It orients onto the earth's magnetic field lines.
Those electrical streams are actually behaving like a slow pendulum. Because they interact with the earth's rotation and also probably the sun's magnetic field, they are basically adjusted poles to the rotation axis.
But, the pendulum is unbalancing itself slowly. As a result of that, it "snaps" its poles every few hundred thousand years or so, and we happen to be in the beginning stage of just such a transition. The transition itself is - as the magnetic field pendulum is oscillating chaotically - going to take a few hundred years, too. It has been estimated that this one started about 200 years ago.
The earth's rotational axis and magnetic poles have already started to deviate from each other, and the magnetic field lowered. On the tipping point, there will most likely be a short period where the magnetic field shuts off. Then no compass will work. Then there will be another brief period of low magnetic field which's poles are not aligned with the rotational axis. But the northern compass needle will point to the south then.
After that, there will be another few hundred thousand years of stable, strong magnetic field with magnetic poles and axis aligned, just the compass north will point to the south. And then it's going to repeat itself.
A few 100.000 years might sound long, but this has happened thousands of times in the past. There will be no microwave oven. A bit more radiation from space will come in, but if we leave some of our ozone layer on, we should be fine with a bit more sunblockers than before during the transitional period.
Then there is the Suns' behaviour to consider. While the magnetic field of Earth is getting weaker, the suns' has increased by 230% since 1901. Solar output has increased by 50% in the same timeframe. We are not alone in our global warming situation, global warming is also being observed in at least 5 other planets in the Solar System. It is entirely possible that the human contribution to global warming is negligible.
Perhaps less than 1% of any climate researcher you might ask would agree with "It is entirely possible that the human contribution to global warming is negligible". The Bush administration wanted it to be so so that they wouldn't have to react to it and helped studies and people along who would dance to their tune - but that had political reasons, not scientific ones.
If solar output had increased by 50% over hundred years, the average temperature on earth's surface would have risen to about +150°C, the oceans would start boiling and, I'd say, we'd generally have noticed that one.
Also, the sun did not increase its magnetic field by 230%. The sun has a 22-year-cycle during which it's magnetic field pulses between orientations. More about that here:
http://csep10.phys.utk.edu/astr162/lect ... netic.html
Last, but not least:
... the Solar System gradually rotates around the Galactic Rim, it regularly passes through the thickest part of the Galactic Plane, (or Disc) from one side to the other in a 62 million year cycle. The galaxy itself has a magnetic field, and the disc is the divider between the North and South poles. For some complex reasons I suspect there is a good chance that passing through the disc will cause the Earth's magnetic field to collapse to zero before flipping poles. If the field collapses, the Earth could effectively become a giant microwave oven for some unknown (hopefully brief) period of time.
If it were as you say, we would pass through the galactic field of lowest field strength in all 62 million years. That would mean, no effect. On us, at all.
Why should the disappearance of one field lead to the collapse of another? And, as said above, the earth's magnetic field will indeed collapse in the comparably near future, as it has done many times before, there will be no microwave oven. Astronauts have already spent a lot of time outside the earth's protective screen, and that can be a problem for long-duration missions (like one to Mars which would take three years atm) but the problem is more the missing atmosphere than the magnetic field.
Sorry, but what you wrote illustrates the shortfalls of theories like the "12-2012, we're gonna burn" one.
L