Professor Gregory Ryskin of the University of Northwestern of Illinois has proposed that oceanic waters are responsible for the changes suffered by the Earth's magnetic field in periods of about a hundred years.
Among the changes in the magnetic field of the Earth, the best known is the investment that occurs every thousand years. However, periodically there are small changes to take into account when navigating or modelling the atmosphere.
Most geophysics consider that, like the big changes, cast iron in the core of the Earth produces small periodic changes. According to scientist Illinois, the electric currents that form the salts dissolved in the water of the oceans are the causes. According to him, these electric currents are relatively large to create a secondary magnetic field and cause small variations in the main magnetic field.