  We discuss how gravitational waves could amplify seed magnetic fields to
strengths capable of supporting the galactic dynamo. We consider the
interaction of a weak magnetic field with gravity wave distortions in almost
FRW cosmologies and find that the magnitude of the original field is amplified
proportionally to the wave induced shear anisotropy and, crucially,
proportionally to the square of the field's initial scale. The latter makes our
mechanism particularly efficient when operating on superhorizon sized magnetic
fields, like those produced during inflation. In that case, the achieved
amplification can easily boost magnetic strengths, which may still lie
relatively close to the galactic dynamo lower limits, well within the currently
accepted range.
