I am not saying there is no crisis coming, but I recall reading that Tehran will be out of water in two weeks, two months ago. What's up with that?
I remember reading about droughts in Syria every year since ~2006. Somehow those news stopped after 5 years. Did they sort it out?
It is unlikely Tehran will just evacuate all at once. They will do something drastic when the problem can no longer be ignored. And random events like rain will delay the inevitable for a while longer.
Perhaps this is how climate change will end up as well.
There will always be lot of other factors - the first time we're going to really collectively notice sea level rise is on the high tide during a storm surge. The rest of the time, the change will be within the range of variation that we're used to dealing with.