M. C. Reader and co-authors present a modeling study of zone changes from pre-industrial times in a recent GRL article. The influence of changes in climate, ozone-depleting substances, N2O, and tropospheric ozone precursors was estimated using equilibrium simulations. From the pre-industrial to the present, it was found that a significant contributor to total column ozone can be attributed to the increase in lower-stratospheric ozone resulting from the increase in tropospheric ozone precursors. The full abstract can be found here.