Neal beat me to it.I would add sleepers over the rafters and add another 7/16 osb and vent that top and bottom so heat from the roof can get out before it gets to the attic. Other than that improve venting and add more insulation.
We call this a cold roof. The sleepers/strapping and the vented space theoretically drains the warmest air out through the ridge vent and the attic stays cooler. The concept is used up here to avoid ice damning in the winter time as well, particularly on cathedral ceilings.