RenderSettings is a static class that modifies a Unity Object with some scene-specific settings.

Interestingly, this means you can query the RenderSettings object directly by invoking the private static method “GetRenderSettings()”. That object can then be modified using a SerializedObject.

There is a property m_IndirectSpecularColor, which is sometimes modified when you are saving scenes. It the only property on this object that isn't directly settable using the SerializedObject. I'm not aware of a way to modify this value, or avoid this Churn.