Once "tipping points" occur, non-linear changes will emerge, and the death toll will be much higher.
As author David Ray Griffin demonstrates in his book, Unprecedented: Can Civilization Survive The CO2 Crisis?, we are facing a constellation of unprecedented, intersecting threats that are leading humanity to increasingly severe catastrophes, and possibly even extinction.
The unprecedented, lethal threats identified by Griffin are these:
Droughts and wild fires
Sea level rise
Fresh water shortage
A closer examination of just one of these threats shows how they are inter-related: