What causes great humanitarian catastrophes?

Generally the cause is a lack of resources: food, water, shelter

There can be bad governance but normally it is starvation of the poorer people and what is now happening in the Middle East is no exception to this rule.

So, if we understand the causes then what comes next might make more sense. The logical outcome of the Middle East and Northern Africa given all present variables is likely millions dying (in the next 10 or more years there from collapsed governments and no infrastructure in place in various countries like Syria, most of Iraq, Yemen and likely soon to be other countries as well the way this whole thing presently looks. And what will only add to this carnage is likely to be the single hottest planet earth in 136 years.