Due to the shifting of the magnetic pole of the Earth's globe, the magnetic variation of meridians also changes and this occurs more or less constantly each year.
Ngenxa yokususwa kwepali kamazibuthe kwiglobhu yomhlaba iindidi zika mazibuthe zeMeridiyani nazo ziyatsha le tinto eyenzeka kancinci nakakhulu ngokuzinzileyo kunyaka ngamnye.