Climate change is real, don't get me wrong. But the main threat to Earth is not climate change, but man himself :)
It will take probably 10 years, at the current pace of temperature rising for 1 level increase in ocean levels (which will make inhabitable large portions of Earth) but just a few seconds of human mistakes (Im talking about the most obvious scenario, a nuclear detonation).
Talking about nuclear holocaust, take time and listen to The Destroyer of Worlds by Dan Carlin (if you are interested in history)