Why must Earth’s magnetic field be continuously regenerated in the core?

Earth’s magnetic field must be continuously regenerated because the geomagnetic dynamo operates within an electrically conducting medium that possesses slight electrical resistance. This resistance would cause the electric currents responsible for the field to dissipate over time if they were not constantly sustained by the motion of the liquid outer core.1

The generation process relies on the dynamo mechanism, where fluid motion in the core moves conducting material across an existing magnetic field to create an electric current. This current, in turn, produces and amplifies the magnetic field. This complex process requires the interaction of thermal convection—driven by the cooling and freezing of the core—and the Coriolis force resulting from Earth’s rotation. Without this ongoing, energy-intensive regeneration, the magnetic field would decay.1