Science is all about preciseness. Without precise mechanism is cleared, no theories is correct.  Every reasonable doubt must be clear out.

There is no field but force existing within matters. Magnetic force is circular electrostatic force carried by circling current and magnets. Magnets are material that have special property, able to form into dipole rings throughout its body. Those rings carry circular electrostatic force.

Sunlight/AC in the atmosphere moves around earth at 1000 miles per hour at the equator, this creates a current/emf in the atmosphere, this emf causes so called magnetic field of earth. it makes campass point to north and navigates birds.