while the drought was the last straw, i think the mismanagement of their water resources by the regime (for embezzlement of public funds, direct or indirect, into insider pockets etc) is the true root cause. There's "enough" water to last thru the current drought, if it was better utilized in the past.
“The government blames the current crisis on changing climate [but] the dramatic water security issues of Iran are rooted in decades of disintegrated planning and managerial myopia,” says Keveh Madani, a former deputy head of the country’s environment department and now director of the United Nations University’s Institute of Water, Environment and Health.
It takes a certain kind of self-delusion to blame climate change and at the same time ignore that your own actions has been one of the major drivers, both in the past and today, of that very same climate change.
While you cannot put the blame on climate change onto iran alone (all of humanity has a part in it), the regime wants to deflect the blame conveniently onto climate change so as to absolve themselves of being responsible for their current water crisis.
So it's not really delusion, but irresponsibility and selfishness.
I’m only putting 2-3% of the global climate change as directly attributable to Iran. And their explicit attempts at preventing progress in stopping it.