Scientists tell us that our magnetic poles have reversed in the past, and that they will again. The last one occurred 780,000 years ago. The average time period between reversals is 450,000 years, but there isn’t really any pattern, it is random. We are overdue by average only.
>” […] Accelerating
This is indisputable – the speed at which the magnetic north pole is moving (not necessarily in the same direction) has recently become much faster. Because this is the entirety of our studies, we don’t know what was normal prior to the 1500s… […]
Not only are the poles moving rapidly – the strength of our magnetic field is diminishing as well:
Rapid changes in the churning movement of Earth’s liquid outer core are weakening the magnetic field in some regions of the planet’s surface, a new study says.
“What is so surprising is that rapid, almost sudden, changes take place in the Earth’s magnetic field,” said study co-author Nils Olsen, a geophysicist at the Danish National Space Center in Copenhagen.
…The changes “may suggest the possibility of an upcoming reversal of the geomagnetic field,” said study co-author Mioara Mandea, a scientist at the German Research Centre for Geosciences in Potsdam. [National Geographic]
[…] Possible Triggers
Scientists have not yet worked out what causes a magnetic reversal, but recent studies of Mercury suggest that the solar wind and particles from the Sun have an effect on planetary cores. My interpretation is that a massive solar storm could be thestraw that breaks the camel’s back and trigger a reversal if the Earth is ready for one. The Electric Universe folk have also suggested that a highly-charged comet passing by could also do the trick. Or perhaps ocean currents, after being affected by climate change, are the trigger? And if climate change is caused by the Sun, then that ties in nicely with the first theory.
Another theory comes from Rich Muller:
where “lighter components, like oxygen, sulfur, and silicon . . . rise toward the core-mantle boundary (CMB).” Accumulating like sediment on the floor of the ocean, these “fall” upward from the core onto the surface of the mantle, which is uneven like the topography of the Earth’s surface. When enough sediment collects, it tumbles like an avalanche, into the outer core, thereby cooling it.
Rare events could trigger really big avalanches at the CMB, however. When a massive asteroid or comet slammed into Earth’s surface at an oblique angle, the lower mantle would jerk sideways, shearing off whole mountains of sediment. As the sediments slide up, a downward-sinking mass of cool iron could completely disrupt large convection cells. Although variously oriented local fields within the core would remain strong, at the surface Earth’s dipole magnetic field would collapse.
And according to Gary Glatzmaier reversals are rooted in chaos theory:
The resulting three-dimensional numerical simulation of the geodynamo, run on parallel supercomputers at the Pittsburgh Supercomputing Center and the Los Alamos National Laboratory, now spans more than 300,000 years.
Our solution shows how convection in the fluid outer core is continually trying to reverse the field but that the solid inner core inhibits magnetic reversals because the field in the inner core can only change on the much longer time scale of diffusion. Only once in many attempts is a reversal successful, which is probably the reason why the times between reversals of the Earth’s field are long and randomly distributed.