Irrational is the complete opposite of what it is. Its perfect rationality and logic. What's irrational is emotion.
Humans have been displaced in one form or another for thousands of years.
There weren't billions of humans thousands of years ago though.
Look how much hassle immigration causes now.
Imagine capital cities going underwater. Or whole countries being near uninhabitable.
If the UK has a few days of snow it grinds to a halt. Imagine if that becomes standard with our badly insulated homes.