The collapse of the Earth's magnetic field, which both guards the planet and guides many of its creatures, appears to have started in earnest about 150 years ago. The field's strength has waned 10 to 15 percent, and the deterioration has accelerated of late, increasing debate over whether it portends a reversal of the lines of magnetic force that normally envelop the Earth.
Scientists have known for some time that the magnetic field is in fact collapsing, at a rate faster than it would if flows of molten iron in the core had stopped completely. And while the consequences would be nowhere near as catastrophic as those in the movie, geophysicists increasingly wonder whether the magnetic field has begun one of its occasional reversals that in the next few thousand years might lead to compasses pointing south instead of north.
The Earth's protective magnetic field is weakening, and if that continues, the field could flip, and compass needles would point south instead of north.