And it is all Bush's fault. Bush and those damned SUVs.
The only hope for mankind is for Our Glorious Leader to tax and spend more.
Seriously, the sun’s reversal of polarity happens every 11 years. A reverse polarity to the earth’s filed only happens at solar max every 22 years.
The magnetosphere field decrease happens every 2 to 3 thousand years. Like the tumblers on a combination lock, the two must align in order to create the perfect storm. You could say that each magnetosphere decrease has a 1 in 22 chance of alignment. This is why the reversals of the earth’s dipolar field are much less frequent...
Per Wiki:
A geomagnetic reversal is a change in the Earth’s magnetic field such that the positions of magnetic north and magnetic south are interchanged. The Earth’s field has alternated between periods of normal polarity, in which the direction of the field was the same as the present direction, and reverse polarity, in which the field was the opposite. These periods are called chrons. The time spans of chrons are randomly distributed with most being between 0.1 and 1 million years with an average of 450,000 years. Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago. However, a study published in 2012 by a group from the German Research Center for Geosciences suggests that a brief complete reversal occurred only 41,000 years ago during the last glacial period. The reversal lasted only about 440 years with the actual change of polarity lasting around 250 years. During this change the strength of the magnetic field dropped to 5% of its present strength. Brief disruptions that do not result in reversal are called geomagnetic excursions.