I read The Uninhabitable Earth by David Wallace Wells about 7 years ago and he talks about the world’s water supply. Yemen in particular is already badly affected and from memory was expected to run out completely by 2030 (vs 2040 when global supply is set to outstrip demand). It’s just one of the interlocking crises we face in the current climate. Scrambling to take control of resources is apparently the path the global powers are going with, as discussed in the book.