From the BBC:

HOW TO THINK ABOUT X | COMMENT & ANALYSIS
Is the world ready for mass migration due to climate change?

National borders are largely arbitrary lines drawn on a map, although there are some physical limits to where humans can live (Credit: Alamy)
By Gaia Vince
17th November 2022

With up to three billion people expected to be displaced by the effects of global warming by the end of the century, should it lead to a shift in the way we think about national borders, asks Gaia Vince?

… Unable to adapt to increasingly extreme conditions, millions – or even billions – of people will need to move.