New Scientist Breaking News – Earth's magnetic decline
Every 300,000 years on average, the north and south poles of the Earth's magnetic field swap places. The field must weaken and go to zero before it can reverse itself. The last such reversal occurred roughly 780,000 years ago, so we are long overdue for another magnetic flip. Once it begins, the process of reversing takes less than 5000 years, experts believe.
If the field does flip 2000 years from now, the Northern Lights will be visible all over the planet during the transition, and solar radiation at ground level will be much more intense, with no field to deflect it.
There is no need to worry, though, argues Gubbins, as our ancestors have lived through quite a few of these transitions already