  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.
