wouldn’t people just migrate away from the equator and habitate places like Northern Canada, Siberia, etc? Yeah it’d be terrible to abandon our cities, but we’d have a long runway to prepare and migrate. Life always finds a way...
The problem with that is that agricultural output in a 3 degree higher world may not be sufficient to sustain a civilization of almost 8 billion people. "Life always finds a way" may be a little sarcastic once people start starving.
One or two million people fleeing from the middle east to Europe caused large political trouble. Imagine what happens when hundreds of millions are displaced.