text: yes, the magnetic fields are already getting weaker, that means Alaska will lose its aurora and the switch of poles can last a few hundred or few thousand years.\n\nThe cause is unknown but the majority of scientists believe that the poles switch not spontaneously but as a result of events that may disrupt the flow of the Earth's core.\n\nScientists read past reversals by the magnetisim of the solidified oceanic rock(at the bottom of the ocean) but to read further back in time they look at sandstone which may have suspended iron particles which can tell of the earth's magnetisim at the time the sandstone was formed