Like the plot of a sci-fi B movie, something weird is happening deep underground where the constant spin of Earth's liquid metallic core generates an invisible magnetic force field that shields our planet from harmful radiation in space. Gradually, the field is growing weaker. Could we be heading for a demagnetized doomsday that will leave us defenseless against the lethal effects of solar wind and cosmic rays?
At the present rate, Earth's magnetic field could be gone within a few centuries, exposing the planet to the relentless blast of charged particles from space with unpredictable consequences for the atmosphere and life. Other possibilities: the field could stop weakening and begin to strengthen, or it could weaken to the point that it suddenly flips polarity—that is, compasses begin to point to the South Magnetic Pole.
An even older record of Earth's fluctuating field than Shaw refers to shows a more complicated picture. Ancient lava flows from the Hawaiian Islands reveal both the strength of the field when the lava cooled and its orientation. "When we go back about 700,000 years," says geologist Mike Fuller of the University of Hawaii, "we find an incredible phenomenon. Suddenly the rocks are magnetized backwards. Instead of them being magnetized to the north like today's field, they are magnetized to the south."
