From Discovery News: Did Magnetic Field Failure Trigger Mass Extinction?
This article talks about a new theory positing that the Permian-Triassic extinction was not only caused by the dust from massive volcano eruptions, but also fluctuations in the magnetic field, which would have allowed cosmic rays to fuck with our atmosphere and cause more cloud cover and cooling. The PT extinction occurred about 250 mya and killed off about 90% of the life on earth. It's a little scary to think things like that could happen at almost any time. I mean, don't they talk about how the magnetic field flips every so many thousands of years, and we're overdue, and the field is losing power and that's what magnetic north is different from actual north?
Plus, extinctions seem to happen pretty regularly. Some say we're in the middle of a human-caused extinction right now.