Time variations in the scale of grand unification

We study the consequences of time variations in the scale of grand unification, M-U, when the Planck scale and the value of the unified coupling at the Planck scale are held fixed. We show that the relation between the variations of the low energy gauge couplings is highly model dependent. It is even possible, in principle, that the electromagnetic coupling alpha varies, but the strong coupling alpha(3) does not (to leading approximation). We investigate whether the interpretation of recent observations of quasar absorption lines in terms of time variation in alpha can be accounted for by time variation in M-U. Our formalism can be applied to any scenario where a time variation in an intermediate scale induces, through threshold corrections, time variations in the effective low scale couplings.