www.cnn.com/2003/TECH/sci...index.html

In part:

"Over the southern Atlantic Ocean, a continued weakening of the magnetic field has diminished the shielding effect it has locally in protecting the Earth from the natural radiation that bombards our planet from space, scientists said.

The weakening if coupled with a subsequently large influx of radiation in the form of protons streaming from the sun, can also affect the chemistry of the atmosphere (said Charles Jackman of NASA's Goddard Space Flight Center) that can lead to significant but temporary losses of atmospheric ozone, he said."