Weakening magnetic field is a return to normal, not a sign of doom
Earth is not heading toward a doomsday reversal of its magnetic field, new research assures.
The planet’s magnetic field is about 10 percent wimpier today than when physicists began keeping tabs on it in the 1800s. In the geologic past, such weakening preceded geomagnetic reversals —swaps of the north and south magnetic poles. Such reversals temporarily make the planet more vulnerable to charged particles blasted off the sun that can disrupt power grids and disable satellites.
But that’s not what’s happening now, a new study suggests. While weakening, Earth’s magnetic field is still strong by historical standards. Retracing the strength of Earth’s magnetic field over the last 5 million years, geophysicists have discovered that the field has been much weaker in the past than previously thought. That means that the average strength of Earth’s magnetic field over that longer time period is about