Peter Olson and Renaud Deguen. 1 Jul 2012. Eccentricity of the geomagnetic dipole caused by lopsided inner core growth. Nature Geoscience 5, 565–569

Lopsided growth of the Earth’s core could explain why its magnetic field reverses direction every few thousand years. If it happened now, there would be solar winds that could knock out global communications and power grids.

There are signs that the next switch may be under way: rapid movements of the field’s axis to the east in the last few hundred years may be a precursor to the north and south poles trading places, the researchers speculate.

Bruce Buffett of the University of California, Berkeley, says the authors present an intriguing proof of concept with their model.

“They are suggesting very cautiously that maybe this rapid change is somehow suggestive of us going into a reversal event,” he says. “You could imagine if the field were to collapse it would have disastrous consequences for communication systems and power grids.”