Magnetic Reversals – 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.
Scientists don’t really know how the process works, and are unable to predict the next reversal. They have been telling us that the process takes hundreds or thousands of years. Recent studies have shown that it can happen in the space of weeks or months, and I suggest it can happen overnight. Perhaps rapid reversals don’t leave much evidence – perhaps rapid reversals are quite common! For example, if it was normal for a double reversal to happen quickly – where the poles return to their original position – we wouldn’t know about any historical instances.
If a reversal involves a dramatic lessening of our geomagnetic field’s strength, then basically our shields are down, and cosmic rays reaching ground-level will greatly increase. Forget about navigational problems – we could be fried.
Studies have shown that pigeons have receptors in their brains that are sensitive to magnetic fields, and presumably those are a reason for their great navigation skills. It is possible that many other animals also have such receptors, but they don’t utilize them as obviously. So during a reversal, the chaos in the animal world could be significant – and of course humans are animals.
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 the straw 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.
Rapid Magnetic Changes
NASA loves telling is that a magnetic reversal takes thousands of years, and that we have nothing to fear. I suggest that NASA should pay more attention to scientific studies that suggest otherwise:
…a new study of ancient copper mines in southern Israel found that the strength of the magnetic field could double and then fall back down in less than 20 years.
This lava, Bogue says, initially started to cool and then was heated again within a year as a fresh lava flow buried it. The fresh lava re-magnetized the crystals within the rock below, causing them to reorient themselves a whopping 53 degrees. At the rate the lava would have cooled, says Bogue, that would mean the magnetic field was changing direction at approximately 1 degree per week.
Palaeomagnetic results from lava flows recording a geomagnetic polarity reversal at Steens Mountain, Oregon suggest the occurrence of brief episodes of astonishingly rapid field change of six degrees per day. The evidence is large, systematic variations in the direction of remanent magnetization as a function of the temperature of thermal demagnetization and of vertical position within a single flow, which are most simply explained by the hypothesis that the field was changing direction as the flow cooled.
the spacing in time between successive flows erupted during a transition cannot be determined accurately because the errors associated with radiometric ages are typically much greater than the duration of a polarity transition.
The final quote suggests that we are not able to detect rapid transitions, and that estimates of durations lasting thousands of years are are a consequence of measurement limitations.
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…