User blog comment:Callofduty4/Call of Duty: Ghosts: An early look/@comment-4832173-20130608195235/@comment-1646923-20130608200152

Here's my handy diagram thing that explains what the timelines are:

The Modern Warfare timeline: The Black Ops timeline: The World War 2 timeline: The Zombies timeline: The Ghosts timeline:

Basically neither of them are related to eachother and are basically in seperate "universes"