Carbon to oxygen ratio (C/O) of gas and dust (ice and refractories) for a disk model in our population. The gas disk has a higher C/O than unity for ~ 0.5 Myr until the disk has cooled slightly. The ice is almost exclusively oxygen rich, apart from a region of the inner disk at late times caused by the slow production and freeze-out of long chain hydrocarbons. We included the excess carbon from the reset model, which eventually disappears after nearly 0.8 Myr. The solids in the region of the disk in which the carbonaceous dust is eroded is always oxygen rich, since the silicates remain in the dust grain while the carbon is removed. C/O changes most at the ice lines of the disk, particularly the water ice line between 2 and 3 AU. The CO ice line is located outside of 60 AU, and hence does not show up in the figure.