The main part of the Earth's magnetic field is generated by convection currents in the Earth's core. These processes are subject to very slow changes, which also result in slow changes in declination. These occur on timescales ranging from a few years to a few million years. In Europe, they currently manifest themselves mainly as a slow westward drift of the isogonic lines by more than 20 km per year.

The service that shows the magnetic declination in Austria (GeoSphere Maps) has now been updated with the latest data (2026).