  Recent revisions of the determination of the solar composition have resulted
in solar models in marked disagreement with helioseismic inferences. The effect
of the composition change on the model is largely caused by the change in the
opacity. Thus we wish to determine an intrinsic opacity change that would
compensate for the revision of the composition. By comparing models computed
with the old and revised composition we determine the required opacity change.
Models are computed with the opacity thus modified and used as reference in
helioseismic inversions to determine the difference between the solar and model
sound speed. An opacity increase varying from around 30 per cent near the base
of the convection zone to a few percent in the solar core results in a
sound-speed profile, with the revised composition, which is essentially
indistinguishable from the original solar model. As a function of the logarithm
of temperature this is well represented by a simple cubic fit. The physical
realism of such a change remains debatable, however.
