BBC – Earth – Earth’s magnetic field now flips more often than ever.
The Earth’s magnetic field, which protects us from potentially dangerous solar radiation, is gradually losing its stability. No need to move underground or build space colonies just yet, though: the changes are taking place over millions of years.
You might assume that compasses will always point north, but in fact the magnetic poles have swapped places many times in the Earth’s history. Earth scientists have long suspected that these flips are becoming more frequent, and that the magnetic field was less prone to pole reversals in the distant past.
Now the most detailed analysis of the geological evidence to date suggests that the field really is slowly destabilising. Whereas in the distant past it reversed direction every 5 million years, it now does so every 200,000 years.
